Дисертації з теми "Thermal stability of insulation"

The sperm chromatin structure assay (SCSA), as developed by Evenson et al.(1980), utilizes flow cytometry to quantify the susceptibility of sperm chromatin to in situ acid denaturation via the metachromatic properties of acridine orange. SCSA is repeatable and has been used to distinguish between fertile and subfertile males in different species; however, it does not permit morphological evaluation of cells. In the present study, the SCSA was modified for the fluorescence/differential interference contrast (DIC) microscope to examine morphology and chromatin stability on the same cell. Semen from six Holstein bulls was collected twice weekly for six weeks. Semen was cryopreserved after collection. A 48-hr scrotal insulation was applied after the first three collections to exert a mild thermal insult to the testes; this induces specific spermatozoal morphological abnormalities to appear in a predictable chronological order, as determined by Vogler et al. (1993). Using DIC optics, sperm head morphology was classified as normal, slightly misshapen, pyriform, severely misshapen, or tailless. Vacuolization in the head region was scored separately as apical, diadem, or random. SCSA and modified-SCSA for fluorescence microscopy were used to assess chromatin instability in the samples. The SCSA parameter of 'cells outside the main population of alpha t' (%COMP alpha t) and the modified-SCSA parameter of '% cells shifted from green' were positively correlated (r=0.84; P<0.01). Both variables were positively correlated with the appearance of tailless, pyriform, severely misshapen, and randomly vacuolated cells (P< 0.01), but not with the appearance of diadems or apical vacuoles. Also, the fluorescence microscope detected a significant shift from green in normally shaped cells appearing in morphologically abnormal ejaculates (P<0.01). These results demonstrate that scrotal insulation-induced morphological abnormalities in spermatozoa signify a perturbation in chromatin structure, and that the chromatin perturbation extends into normally shaped cells in the same ejaculate.
Master of Science

La tesi si è svolta nel corso di uno stage di quasi nove mesi all'interno del laboratorio elettrico di alta tensione del reparto R&D di Prysmian, leader mondiale dei sistemi elettrici in cavo. La tesi si è articolata nelle fasi seguenti: 1) analisi dei fondamenti teorici dei sistemi elettrici in cavo ad alta tensione in corrente continua (HVDC); 2) caratterizzazione elettrica di materiali isolanti innovativi per lo sviluppo di sistemi in cavo HVDC. Più in dettaglio tale caratterizzazione è consistita nelle fasi seguenti: a) progettazione e/o realizzazione dei set-up di prova; b) esecuzione delle prove di conducibilità elettrica su provini piani di materiale isolante costituiti da diverse mescole candidate per la realizzazione di cavi modello nella seconda parte della caratterizzazione (vedi seguito); c) elaborazione dei dati delle prove di cui al punto b) per ricavare i parametri σ0, α e β della conducibilità di ogni mescola isolante testata - e quindi l’andamento della conducibilità delle mescole in funzione della temperatura e del gradiente elettrico – così da selezionare le mescole migliori per la realizzazione dei cavi modello (cavi in scala ridotta con dimensioni standardizzate realizzati ai fini di prove di sviluppo); d) esecuzione delle prove di tenuta in AC sui cavi modello selezionati; e) esecuzione delle prove di rigidità ad impulso atmosferico su cavi modello; f) esecuzione delle prove di stabilità termica su cavi modello. I risultati di tutte le prove condotte hanno consentito di determinare quali fossero, tra tutte le mescole prese in esame, le più performanti dal punto di vista elettrico.

The aim of this doctorate is to investigate an alternative to petroleum based thermal insulations, by using natural and recycled materials. The methodology used is centered on the use of the basic ingredients of waste animal fats, waste oils and a potash derived lye mixture, combined to create a crude soap. This soap is aerated to produce a lightweight structure that is capable of preventing or reducing heat transfer between areas of differing temperatures. Experimental testing reveals that this non-toxic product can be strengthened, made waterproof, vermin proof and fire retardant, whilst the results from the thermal testing laboratory confirm that aerated soap insulation functions as a moderate performer. The step-by-step experimental methodology applied, alongside the thermal conductivity and resistance results contained within this thesis, can be used as a gauge for future potential improvements to build from. Currently there are gaps in knowledge and practice with regards to environmental thermal insulation. There are other environmental insulations, but more research needs to be initiated regarding recyclable, biodegradable, renewable and organic components and ingredients within the insulation make-up. Industry trends are to improve the better performing petroleum insulations, whilst seemingly unwilling to compromise on environmental problem relief. This doctorate provides suggestions on how to reduce some of the environmental problems by replacing or diluting the toxic elements of petroleum insulation. Soap insulation is unique and as such makes a significant contribution to knowledge. This uniqueness is evidenced through the literature review and the systematic investigation of the research topic. The awarding of a worldwide patent on soap insulation protects the manufacture of thermal insulation comprising of solid aerated soap panels, derived from animal fats and lye. This idea of combining basic soap ingredients, then aerating the mixture to create thermal insulation is new and as such contributes to new knowledge. The publishing of a journal paper titled “Can Soap be a Sustainable Alternative to Petroleum-Based Thermal Insulation?” in the journal of Structural Survey. (Read & Arayici, 2015) emphasize the contribution of this research. Read & Arayici, (2015) describes the ingredients used, the manufacturing process and the improvement measures taken to create the soap insulation. Publishing is one method of making this research known to the global community. Academics can then engage with fellow academics or collaborate with industry to further this research or to commercialise this knowledge. Aerated soap research can widen the understanding of possible new alternative thermal insulation ideas. This creates a small yet original and significant opportunity to reduce the associated carbon footprint and environmental costs accrued each time that petroleum insulation is produced.

We are coming to realize that there is an urgent need to reduce energy usage in buildings and it has to be done in a sustainable way. This thesis focuses on the performance of the building envelope; more precisely thermal performance of walls and super insulation material in the form of vacuum insulation. However, the building envelope is just one part of the whole building system, and super insulators have one major flaw: they are easily adversely affected by other problems in the built environment.  Vacuum Insulation Panels are one fresh addition to the arsenal of insulation materials available to the building industry. They are composite material with a core and an enclosure which, as a composite, can reach thermal conductivities as low as 0.004 W/(mK). However, the exceptional performance relies on the barrier material preventing gas permeation, maintaining a near vacuum into the core and a minimized thermal bridge effect from the wrapping of barrier material round the edge of a panel. A serpentine edge is proposed to decrease the heat loss at the edge. Modeling and testing shows a reduction of 60% if a reasonable serpentine edge is used. A diffusion model of permeation through multilayered barrier films with metallization coatings was developed to predict ultimate service life. The model combines numerical calculations with analytical field theory allowing for more precise determination than current models. The results using the proposed model indicate that it is possible to manufacture panels with lifetimes exceeding 50 years with existing manufacturing. Switching from the component scale to the building scale; an approach of integrated testing and modeling is proposed. Four wall types have been tested in a large range of environments with the aim to assess the hygrothermal nature and significance of thermal bridges and air leakages. The test procedure was also examined as a means for a more representative performance indicator than R-value (in USA). The procedure incorporates specific steps exposing the wall to different climate conditions, ranging from cold and dry to hot and humid, with and without a pressure gradient. This study showed that air infiltration alone might decrease the thermal resistance of a residential wall by 15%, more for industrial walls. Results from the research underpin a discussion concerning the importance of a holistic approach to building design if we are to meet the challenge of energy savings and sustainability. Thermal insulation efficiency is a main concept used throughout, and since it measures utilization it is a partial measure of sustainability. It is therefore proposed as a necessary design parameter in addition to a performance indicator when designing building envelopes. The thermal insulation efficiency ranges from below 50% for a wood stud wall poorly designed with incorporated VIP, while an optimized design with VIP placed in an uninterrupted external layer shows an efficiency of 99%, almost perfect. Thermal insulation efficiency reflects the measured wall performance full scale test, thus indicating efficiency under varied environmental loads: heat, moisture and pressure. The building design must be as a system, integrating all the subsystems together to function in concert. New design methodologies must be created along with new, more reliable and comprehensive measuring, testing and integrating procedures. New super insulators are capable of reducing energy usage below zero energy in buildings. It would be a shame to waste them by not taking care of the rest of the system. This thesis details the steps that went into this study and shows how this can be done.
QC 20120228

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 74-76).
Buildings consume too much energy. For example, 16.6% of all the energy used in the United States goes towards just the heating and cooling of buildings. Many governments, organizations, and companies are setting very ambitious goals to reduce their energy use over the next few years. Because the time periods for these goals are much less than the average lifetime of a building, existing buildings will need to be retrofitted. There are two different types of retrofitting: shallow and deep. Shallow retrofits involve the quickest and least expensive improvements often including reducing infiltration around windows, under doors, etc and blowing more insulation into the attic. Deep retrofits are those that involve costly renovation and typically include adding insulation to the walls and replacing windows. A new, easily installable, inexpensive, and thin insulation would move insulating the walls from the deep retrofit category to the shallow retrofit category and thus would revolutionize the process of retrofitting homes to make them more energy efficient. This thesis provides an overview of a concept for a new, easily installable, inexpensive, thin aerogel-based insulation and goes into detail on how the thermal properties of the aerogel were measured and validated. The transient hot-wire method for measuring the thermal conductivity of very low thermal conductivity silica aerogel (1 0mW/m K at 1 atm) along with a correction for end effects was validated with the NIST (National Institute of Standards and Technology) Standard Reference Material 1459, fumed silica board to within 1 mW/mK. Despite the translucence of the aerogel at certain wavelengths, radiation is not an issue through the aerogel during the hot-wire test but may be an issue in actual use as an insulation. The monolithic aerogel thermal conductivity drops significantly with slightly reduced pressure (3.2 mW/m K at 0.1atm). For the final composite insulation, the new silica aerogel formula is a great choice and it is recommended to reduce the pressure around the aerogel to 1 / 1 0 th. In the future, a prototype of an insulation panel combining a 3-D truss structure, monolithic or granular silica aerogel, and reduced pressure will be constructed and tested.
by Ellann Cohen.
S.M.

Cette thèse s'inscrit dans un objectif à long terme de déterminer in situ (et/ou en usage) les propriétés thermiques des matériaux isolants du bâtiment. Notre objectif est de réduire l'écart entre la mesure en laboratoire et la performance réelle des isolants dans les parois de bâtiments. Nous nous sommes fixés deux objectifs principaux au cours de cette étude: 1- Étudier la possibilité d'utiliser la sonde cylindre à choc thermique pour la mesure des caractéristiques thermiques des matériaux isolants du bâtiment. 2- Étudier le comportement thermique d'un isolant en usage en utilisant un montage basé sur le principe de la boite chaude gardée. Cet équipement permet d'effectuer des études dans des conditions climatiques en température et en humidité proches de situations réelles supportées par l'enveloppe d'un bâtiment. Ce travail a permis d'identifier des verrous lors de l'utilisation d'une sonde à choc thermique pour caractériser des matériaux isolants. Il a aussi montré l'intérêt de la boite chaude gardée pour effectuer des études dans des conditions réelles et pour étudier les transferts de chaleur et de masse dans les parois de bâtiments
This thesis is part of a long-term objective to determine in situ (and / or in use) the thermal properties of building insulation materials. We want to reduce the gap between the laboratory measurement and the actual performance of insulation in buildings walls. We have set two main objectives during this study: 1- To study the possibility of using a non-steady state hot probe for measuring thermal properties of insulants. 2- To study the thermal behaviour of insulation materials in use by using a guarded hot box. Climatic conditions in temperature and humidity close to real situations can be submitted supported by hot and cold cells. This work has shown the interest of using thermal probe to characterize insulating materials. Guarded hot box is also interesting for studies in real conditions and to followheat and mass transfer in buildings walls

Дисертація на здобуття наукового ступеня кандидата технічних наук (доктора філософії) за спеціальністю 141 "Електроенергетика, електротехніка та електромеханіка" (14 – Електрична інженерія) – Національний технічний університет "Харківський політехнічний інститут", м. Харків, 2020 р. Дисертаційна робота присвячена підвищенню експлуатаційних характеристик суднових кабелів за рахунок технологічних режимів охолодження та радіаційного опромінення ізоляції і оболонки на основі сучасних, які не поширюють полум'я, безгалогенних полімерних композицій, що забезпечують необхідний комплекс електричних, фізико-механічних параметрів при відповідному контролі технологічних процесів. Для досягнення цієї мети були поставлені задачі: – довести доцільність поступового охолодження поліетиленової ізоляції високовольтних силових кабелів для забезпечення як експлуатаційних параметрів, так і стабільності характеристик в процесі експлуатації; – обґрунтувати застосування методу електротеплової аналогії для побудови математичної моделі охолодження ізольованої струмопровідної жили з урахуванням розподілу температури по товщині ізоляції в несталому тепловому режимі; – розробити методику розрахунку технологічних параметрів режиму охолодження силових кабелів, що ґрунтується на розрахунку нелінійної теплової схеми заміщення ізольованої струмопровідної жили в несталому тепловому режимі з урахуванням залежності від температури теплового опору і теплоємності ізоляції методами дискретних резистивних схем заміщення і вузлових потенціалів; – визначити вплив технологічних режимів охолодження на розподіл температури по товщині екструдованої ізоляції та обґрунтувати тривалість перехідного процесу, що відповідає досягненню однакової температури по всій товщині ізоляції силових кабелів різного конструктивного виконання в різні моменти часу в залежності від температури води, що охолоджує; – експериментально перевірити ефективність виявлення технологічних дефектів в конструкції силового суднового кабелю за характеристиками часткових розрядів; – створити методику оптимізації силового суднового кабелю коаксіальної конструкції для забезпечення максимального розсіювання потужності теплового потоку в навколишнє середовище, що обумовлює збільшення струмового навантаження, за умови теплової стійкості ізоляції; – довести ефективність застосування захисної полімерної оболонки з високими теплопровідними властивостями для підвищення струмового навантаження силових суднових кабелів; – визначити вплив енергії прискорених електронів на механічні та електричні характеристики суднових кабелів та встановити діапазон коефіцієнта опромінення ізоляції, що забезпечує підвищення експлуатаційних характеристик, на підставі кореляційного зв'язку між електричними та механічними характеристиками радіаційно-модифікованої високонаповненої антипіренами безгалогенної композиції на основі співполімеру етилен-вінілацетату; – перевірити ефективність розподілу поглиненої дози по периметру й довжині при радіаційному опроміненні суднових кабелів за результатами фізико-механічних та теплових випробувань безгалогенної, яка не поширює полум'я, полімерної захисної оболонки кабелю; – визначити на підставі прискореного теплового старіння теплову стійкість радіаційно-модифікованої безгалогенної, яка не поширює полум'я, полімерної захисної оболонки, для прогнозування строку служби суднових кабелів та обґрунтувати можливість роботи в умовах підвищеної вологості і високих робочих температур неекранованого кабелю на основі неекранованих кручених пар з термопластичними ізоляцією і захисною оболонкою. Об'єкт дослідження – технологічні режими охолодження та радіаційного опромінення електричної ізоляції суднових кабелів, виготовленої з наповненої антипіренами безгалогенної композиції на основі поліолефінів. Предмет дослідження – експлуатаційні електричні, фізико-механічні та теплові характеристики полімерної ізоляції і оболонки, на основі наповненої антипіренами безгалогенної композиції, суднових кабелів. Методи дослідження. Теоретичні та експериментальні дослідження базуються на використанні методів чисельного та фізичного моделювання технологічних режимів охолодження та радіаційного опромінення прискореними електронами електричної полімерної ізоляції та захисної оболонки суднових кабелів. Методи теорії нестаціонарної теплопровідності для розрахунку режиму охолодження полімерної ізоляції кабелю. Диференційні рівняння теплопровідності та електропровідності. Метод електротеплових аналогій для визначення розподілу температури по товщині ізоляції в різні моменти часу, в залежності від температури води, що охолоджує судновий силовий кабель. Нелінійні теплова та електрична схеми заміщення ізольованої струмопровідної жили в перехідному тепловому режимі. Неявний метод Ейлера та метод вузлових потенціалів для отримання розподілу температури по товщині ізоляції кабелю. Метод оптимізації конструкції силового кабелю за умови забезпечення охолодження в експлуатації для підвищення струмового навантаження. Рівняння теплового балансу для визначення теплової стійкості ізоляції в експлуатації. Теорія радіаційного зшивання для визначення оптимальної дози опромінення полімерної ізоляції. Теорія теплового старіння ізоляції для прогнозування строку служби суднових кабелів в експлуатації. Апроксимація експериментальних електричних, фізико-механічних й теплових характеристик радіаційно-модифікованої ізоляції суднових кабелів. Кореляційний та регресійний аналіз електричних, механічних й теплових характеристик в процесі радіаційного модифікування полімерної ізоляції та захисної оболонки суднових кабелів. Техніка реєстрації часткових розрядів у високовольтній твердій полімерній ізоляції для виявлення дефектів на технологічній стадії виготовлення силових суднових кабелів. В роботі отримані такі наукові результати. У дисертаційній роботі вирішено науково-практичну задачу з підвищення експлуатаційних характеристик суднових кабелів за рахунок технологічних режимів охолодження та опромінення електричної ізоляції на основі сучасних безгалогенних полімерних композицій, які не поширюють полум'я. Удосконалено математичну модель технологічного процесу охолодження ізольованої струмопровідної жили в несталому тепловому режимі шляхом урахування температурної залежності теплофізичних характеристик полімерної ізоляції підчас розрахунку розподілу температури по товщині поліетиленової ізоляції в різні моменти часу в залежності від температури води при поступовому охолодженні, що дозволило визначити умови для забезпечення стабільних характеристик суднового силового кабелю в експлуатації. Запропоновано критерій для визначення технологічних параметрів режиму охолодження силових суднових кабелів, який являє собою час перехідного процесу охолодження ізольованої струмопровідної жили для досягнення однакової температури по всій товщині полімерної ізоляції. Встановлено оптимальну товщину полімерної захисної оболонки за умови довготривалої теплової стійкості радіаційно-зшитої ізоляції на основі поліолефінів, що забезпечує підвищення на 30 % струмове навантаження силового суднового кабелю коаксіальної конструкції. Визначено діапазон коефіцієнта опромінення прискореними електронами безгалогенної, що не поширює полум'я ізоляції суднових кабелів, що гарантує підвищення електричного опору радіаційно-модифікованої полімерної ізоляції більш ніж в два рази, пробивної напруги на постійному струмі в 1,3 рази відносно неопроміненого стану. Встановлено кореляцію між механічними і електричними характеристиками радіаційно-модифікованої ізоляції з безгалогенної композиції на основі поліолефінів, в залежності від лінійної швидкості проходження кабелю під пучком електронів при незмінному струмі пучка електронів. Встановлено, в залежності від технологічних параметрів режиму опромінення суднових кабелів, розподіл поглиненої дози по периметру і довжині полімерної захисної оболонки з безгалогенної композиції, яка не поширює полум'я, що дозволяє визначити дозу опромінення кабелів, яка забезпечує підвищення стійкості захисної оболонки до дії агресивних хімічних речовин при збереженні високих фізико-механічних характеристик Експериментально, на підставі прискореного старіння неекранованого кабелю на основі неекранованих кручених пар, з термопластичної поліетиленової ізоляції в захисній оболонці на основі полівінілхлоридного пластикату за умови адекватного старіння в експлуатації, доведено стійкість конструкції до підвищеної температури та вологості, що дозволяє прогнозувати строк служби суднових кабелів в залежності від робочої температури. Розроблено методику розрахунку технологічних параметрів режиму охолодження силових кабелів, що ґрунтується на розрахунку нелінійної теплової схеми заміщення ізольованої поліетиленом струмопровідної жили в несталому тепловому режимі, з урахуванням залежності від температури теплового опору і теплоємності, методами дискретних резистивних схем заміщення і вузлових потенціалів. Запропонована методика та алгоритми можуть бути застосовані для визначення технологічних режимів охолодження полімерної ізоляції кабелів без застосування дороговартісних натурних експериментів, що особливо важливо при освоєнні нових матеріалів та конструкцій, а також при модернізації існуючого на кабельних підприємствах обладнання, для охолодження силових, симетричних, радіочастотних та оптичних кабелів. Доведено ефективність реєстрації часткових розрядів у високовольтній твердій ізоляції для виявлення дефектів на технологічній стадії виготовлення силових суднових кабелів, а також для налаштування технологічного процесу охолодження. Розроблено методику розрахунку теплопередачі в одножильному силовому кабелі коаксіальної конструкції на підставі критеріальних рівнянь природної конвекції, для оптимізації конструкції силового суднового кабелю, для забезпечення максимальної лінійної щільності теплового потоку, що розсіюється з поверхні кабелю. Показано ефективність застосування полімерних матеріалів на основі мікро- і нанокомпозитів з високими теплопровідними властивостями для захисної оболонки силових високовольтних суднових кабелів, що забезпечують збільшення розсіювання кабелем теплової потужності на 30 %. Встановлено, що енергія прискорених електронів на рівні 0,5 МеВ забезпечує більш високий ступінь зшивання полімерної безгалогенної ізоляції на основі високонаповненої антипіренами композиції в порівнянні з енергією 0,4 МеВ при однаковому коефіцієнті опромінення, струмі пучка і кількості проходів ізольованої жили під пучком електронів. Доведено підвищення механічної міцності при розтягуванні, електричного опору ізоляції та пробивної напруги на постійному струмі радіаційно-модифікованої полімерної безгалогенної ізоляції з коефіцієнтом опромінення 5–7 м/(мА∙хв) при сталому значенні відносного подовження при розриві ізоляції на рівні не менше 120 %, що забезпечує компроміс між еластичністю і жорсткістю суднового кабелю. Встановлено зростання в 1,5–2 рази часу досягнення критичного параметра – відносного подовження при розриві радіаційно-модифікованої полімерної захисної оболонки на основі безгалогенної композиції, в порівнянні з не модифікованою термопластичною оболонкою, що еквівалентно збільшенню строку експлуатації в 1,5–2 рази суднового контрольного кабелю в області максимальних робочих температур. Матеріали дисертаційної роботи використовуються в навчальному процесі на кафедрі електроізоляційної та кабельної техніки Національного технічного університету "Харківський політехнічний інститут" при підготовці бакалаврів та магістрів за спеціальністю "141 – електроенергетика, електротехніка та електромеханіка" спеціалізації "141.04 Електроізоляційна, кабельна та оптоволоконна техніка"; у ТОВ "Азовська кабельна компанія" (м. Бердянськ) при розробці і визначенні оптимальних технологічних параметрів режимів виготовлення безгалогенних суднових кабелів, що не розповсюджують горіння, асоціації "Укрелектрокабель", в ПАТ "Завод "Південкабель". Дисертаційна робота виконана в ПрАТ "Український науково-дослідний інститут кабельної промисловості" (м. Бердянськ) та на кафедрі електроізоляційної та кабельної техніки Національного технічного університету "Харківський політехнічний інститут" (м. Харків), згідно програм наукових досліджень ПрАТ "Український науково-дослідний інститут кабельної промисловості" (ПМ ЕИЮВ.505.564–2018 "Вивчення термічної стійкості оболонки кабелю марки СПОВЕнг-FRHF 12x2,5 до та після опромінення швидкими електронами", ПМ ЕИЮВ.505.584–2019 "Визначення величини та розподілу поглиненої дози при радіаційному модифікуванні оболонки суднових кабелів, що не розповсюджують полум'я"), де здобувач був одним з розробників і виконавців програм.
Ph.D. thesis undertaken in research specialization 141 "Electric Power Engineering, Electrical Engineering and Electric Mechanics" (14 – Electrical Engineering). – National Technical University "Kharkiv Polytechnic Institute", Ministry of Education and Science of Ukraine, Kharkiv, 2020. The dissertation is devoted to increasing of the operational properties of shipboard cables due to the technological modes of cooling and electron beam irradiation of insulation and sheath based on modern flame retardant halogen-free polymeric compounds, which provide the necessary complex of electrical, physical and mechanical properties with appropriate control of technological processes. To achieve this, the following tasks were set: – to prove the expediency of gradual cooling of polyethylene insulation of high-voltage power cables to ensure both operational parameters and stability of properties during operation; – to substantiate the application of the method of electro-thermal analogy for the construction of a mathematical model of cooling of insulated conductor taking into account the temperature distribution over the thickness of insulation in a non-constant thermal mode; – to develop a method of calculating the technological parameters of the cooling mode of power cable, based on the calculation of a nonlinear thermal equivalent circuit of insulated conductor in a non-constant thermal mode, taking into account dependence the thermal resistance and heat capacity of the insulation from the temperature by methods of discrete resistive equivalent circuits; – to determine the influence of technological cooling modes on the temperature distribution in the thickness of extruded in sulation and to justify the duration of the transition process, which corresponds to achievement of the same temperature over the entire thickness of power cables insulation various design at different time points, depending on the cooling water temperature; – to verify experimentally the efficiency of detecting technological defects in the design of the power shipboard cable by partial discharges values; – to create a methodology for optimizing the power shipboard cable with coaxial construction to ensure maximum heat flow power dissipation into the environment, which causes an increase in current load, if insulation thermal resistance provided; – to prove the efficiency of the use a protective polymer sheath with high thermal conductive properties to increase the current load of power shipboard cables; – to determine the effect of accelerated electron beam energy on the mechanical and electrical properties of shipboard cables and determine the irradiation coefficient range for insulation which provides an increase of operational characteristics, on the basis of correlation between the electrical and mechanical properties of filled with flame retardants halogen-free compound based on ethylene-vinyl acetate modified by electron beam; – to verify the efficiency of absorbed dose distribution along the perimeter and length of shipboard cables after irradiation according to obtained results of mechanical and thermal tests of polymeric halogen-free flame retardant protective sheath of cable; – to determine the thermal stability of the halogen-free flame-retardant polymeric protective sheath modified by irradiating, on basis of accelerated thermal aging, to predict the service life of shipboard cables and to substantiate the possibility of operation in conditions with high humidity and high operating temperatures for unscreened cable with unscreened twisted pairs and thermoplastic insulation and protective sheath. Object of research – technological modes of cooling and irradiation of electrical insulation of shipboard cables, based on halogen-free filled with flame retardants polyolefin compound. Subject of research – electrical, mechanical and thermal operational properties of the shipboard cables polymer insulation and sheath based on filled with flame retardants halogen-free compounds. Research methods. Theoretical and experimental studies are based on the use of methods of numerical and physical modeling of technological modes of cooling and electron beam irradiation of polymeric electrical insulation and protective sheath of shipboard cables. Methods of theory of non-stationary thermal conductivity to calculation of cooling mode of polymeric cable insulation. Differential equations of thermal conductivity and electrical conductivity. The method of electro-thermal analogies to determine the temperature distribution in the thickness of insulation at different time points, depending on the temperature of cooling water for shipboard power cable. Nonlinear thermal and electrical equivalent circuits of insulated conductor in transient thermal mode. Implicit Euler method and nodal potentials method for obtaining temperature distribution in thickness of cable insulation. A method of optimizing the design of the power cable provided cooling during operation to increase the current load. Thermal balance equation to determining the thermal resistance of insulation during operation. Irradiation crosslinking theory to determine the optimal irradiation dose of polymeric insulation. The theory of thermal aging of insulation to predict the service life of shipboard cables. Approximation of experimental electrical, mechanical and thermal properties of modified by irradiation insulation of shipboard cables. Correlation and regression analysis of electrical, mechanical and thermal properties after modification by irradiation of polymeric insulation and protective sheath of shipboard cables. Partial discharge detection technique in high voltage solid polymeric insulation for defect detection on technological stage of production power shipboard cable. The following scientific results are obtained in the work. The dissertation solves the scientific and practical problem of increasing the operational properties of shipboard cables due to the technological modes of cooling and irradiation of electrical insulation based on modern halogen-free flame retardant polymeric compounds. The mathematical model of technological process of cooling insulated conductor in unsteady thermal mode, by taking into account dependence of thermal and physical characteristics of polymeric insulation from the temperature, for determine the temperature distribution throughout the thickness of polyethylene insulation at different time points depending on water temperature under gradual cooling, has been improved. Mathematical model allows to determine the conditions for ensuring stable characteristics of the shipboard power cable during operation. The criterion for determination of technological parameters of the cooling mode of power shipboard cables, which is the time of the transitional process of cooling the insulated conductor to achieve an equal temperature throughout the thickness of the polymeric insulation, is proposed. The optimum thickness of the polymeric protective sheath on condition of long-term thermal stability of irradiated cross-linked based on polyolefin insulation has been established. It provides a 30 % increase current load of the coaxial design shipboard power cable. The range of irradiation coefficient for halogen free flame retardant insulation of shipboard cables when guarantees increasing electrical resistance of polymeric insulation modified by electron beam more than twice, the breakdown direct current voltage 1,3 times relative to the non-irradiated condition, is determined. The correlation between mechanical and electrical properties of halogen-free based on polyolefin insulation modified by electron beam, depending on the linear velocity of the cable under the electron beam and constant value of electron beam current. The distribution of the absorbed dose along the perimeter and length of the halogen-free flame retardant polymeric protective sheath depending on the technological parameters of the irradiation modes of shipboard cables, is established and allows to determine the irradiation dose for cables, when protective sheath provides increasing the resistance to aggressive chemicals while high physical and mechanical properties is still available. The stability of the cables structure to high temperature and humidity is experimentally proved on the basis of accelerated aging of unscreened cable with unscreened twisted pairs, with thermoplastic polyethylene insulation and protective polyvinylchloride sheath with adequate aging during operation. It allows predicting the service life of shipboard cables depending on the operating temperature. A technique for calculating the technological parameters of the power cable cooling mode by the methods of discrete resistive equivalent circuits has been developed. A technique based on the calculation of a nonlinear thermal scheme of substitution of conductor with polyethylene insulation in a non-constant thermal mode, taking into account the dependence of thermal resistance and heat capacity from the temperature. The proposed methodology and algorithms can be applied to determine the technological modes of cooling cable polymeric insulation without using expensive full-scale experiments, especially important for the new compounds development and cable constructions, as well as modernization available at cable factories equipment for cooling power cable, data cable with twisted pairs, radio frequency and optical cables. The efficiency of determining partial discharges in high-voltage solid insulation has been proved to detect defects at the technological stage of the producing of power shipboard cables, as well as to adjust the technological process of cooling. The methodology for heat transfer in a coaxial design single-core power cable based on criterial equations of natural convection has been developed to optimize the design of the power shipboard cable to ensure the maximum linear density of heat flow dissipated from the cable surface. The efficiency of application of polymeric materials based on micro- and nanocomposites with high thermal conductivity for sheath of high-voltage shipboard cables, providing a 30 % increase in thermal dissipating of power cable, is shown. It is established the energy of accelerated electrons 0.5 MeV provides a higher degree of crosslinking of polymeric halogen-free insulation based on filled with flame retardants compound compared to the energy of 0.4 MeV at the same irradiation coefficient, electron beam current and the number of wire passages under electron beam. It is established an increase of tensile strength, electrical insulation resistance and breakdown DC voltage of crosslinked polymeric halogen-free insulation with irradiation coefficient 5-7 m/(mА∙min) with constant value of elongation at break not less than 120 % which ensure a compromise between rigidity and flexibility of the shipboard cable. It is established an increase in 1,5–2 times the time of reaching the critical parameter – elongation at break of the modified by electron beam polymeric sheath based on a halogen-free compound compared to the same thermop lastic non-modifying sheath. It is an increase service life of the shipboard control cable at maximum operational temperatures in 1,5–2 times. The materials of the dissertation are used at the educational process Department of Electrical Insulating and Cable Technique of National Technical University "Kharkiv Polytechnic Institute" at education bachelors and masters in disciplines of specialty "141 – Electric Power Engineering, Electrical Engineering and Electric Mechanics" (specialization "141.04 Electrical Isolating, Cable and Fiber-Optic Technique"), at "Azov Cable Company" (Berdians'k) at development and determination of optimal technological parameters of production modes of halogen-free, flame retardant shipboard cables, Association "Ukrelectrocable", in PJSC "Yuzhkable Works". Dissertation work was performed at the PJSC "Ukrainian Scientific and Research Institute of Cable Industry" (Berdians'k) and Department of Electrical Insulating and Cable Technique of National Technical University "Kharkiv Polytechnic Institute" (Kharkiv) according to research programs of PJSC "Ukrainian Scientific and Research Institute of Cable Industry" (PM EIUV.505.564–2018 "The research of thermal stability of the sheath cable SPOVEng-FRHF 12x2,5 before and after exposure under electron beam", PM EIUV.505.584–2019 "Determination of the quantity and distribution of the absorbed dose after irradiation of the sheath of shipboard flame retardant cables") wherein the applicant was one of the program developers and executor of individual sections.

Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Sciences & Engineering, 1994.
Includes bibliographical references (leaf 55).
by Patrick Joseph Keenan.
M.S.
Nav.E.

Fibre-reinforced polymeric composites for structural applications are required to conform to specific fire performance requirements and to retain their mechanical integrity after exposure to heat/fire. Many polymeric composites will lose their structural integrity when exposed to temperatures close to the glass transition temperature of the resin matrix. The most effective technique of protecting these materials against heat and fire is the use of surface coatings, which can inhibit or reduce the heat transfer from the fire/heat source to the underlying structure. In this PhD, novel thermal barrier coatings and techniques of their application on the surface of glass fibre-reinforced epoxy (GRE) composites were developed. These include: (1) commercially available intumescent coatings applied by paint brush and roller (2) nanoclays, dispersed in a solvent and sprayed on plasma activated GRE laminate surfaces (3) ceramic nano/microparticles dispersed in a flame retardant resin, applied by painting or K-bar application and (4) chemical coating obtained by applying phosphorus containing monomers (vinyl phosphonic acid) on a GRE surface by paint brush and polymerisation using UV radiation. Surface characterisation was carried out on each coating by scanning electron microscopy (SEM) and a water drop test. These results showed that the application method used plays an important role in determining the uniformity of the coating. Plasma treatment increased the hydrophilicity of the GRE composite surface, while in the presence of a resin binder, the coating established a hydrophobic surface. The effect of these coatings on the flammability of the composites was studied by a cone calorimeter at different heat fluxes, and the thermal barrier effect of the coatings was measured by insertion of thermocouples into the laminate during the cone experiments and measuring the time for the back surface temperature to reach the glass transition temperature of the resin. Intumescent coatings, as expected, showed the best performance and were used to set a benchmark for the performance of the other coatings. The nanoparticle and micro-ceramic particle coatings can act as thermal barriers. However, their concentration on the surface of laminates was not high enough to provide effective thermal protection for an extended period of time. The chemical (poly (vinyl phosphonic acid)) coating provided the best thermal barrier of the coatings due to its ability to form an intumescent char. Three point blending flexural and impact tests were used to study the effect of the coatings on the mechanical properties of the laminates. The contribution of the coating to the impact and flexural modulus of the laminates is related to the thickness of the coating and its mechanical properties. Thus, thin coatings showed better results than thick coatings. Each coating had a minimal effect on the mechanical properties of the GRE composite, while they improve the retention of mechanical property after exposure to heat, with the chemically coated samples performing the best, due to the formation of a thick intumescent char. A tape pull was performed to study the adhesion of the coatings on the GRE surfaces. All coatings containing resin binder or polymerized on the GRE surfaces were durable and did not peel off. The durability to water was tested by a water soak test. The nano/micro particulate ceramic coatings showed the best performance, whereas the chemical coatings showed the worst behaviour due to the highly hydrophilic nature of the poly (vinyl phosphonic acid).

Dans les turbines à gaz aéronautiques, les matériaux employés dans les parties les plus chaudes sont soumis à des environnements chimiques extrêmes, sous fortes pressions et températures. Ainsi, des systèmes de revêtement « barrière thermique, BT » sont appliqués sur les substrats en superalliage à base nickel. Ces systèmes multicouches (zircone stabilisée à l’yttrine (YSZ) /couche de liaison en MCrAl ou NiPtAl/substrat refroidi) permettent d’abaisser la température à la surface des pièces, conduisant à un comportement thermomécanique adéquat et à une diminution des vitesses d’oxydation/corrosion. Cependant, l’augmentation nécessaire de la température des gaz d’entrée de turbine (augmentation du rendement moteur) entraîne de nouveaux phénomènes de dégradation (CMAS) et une perte d’efficacité des revêtements BT actuels. Par ailleurs, l’évaluation de la durée de vie des revêtements BT s’avère cruciale pour déterminer celle des moteurs. Comprendre l’évolution du pouvoir isolant des revêtements BT en environnement agressif constitue donc un enjeu essentiel du point de vue scientifique et technologique. A partir des revêtements couramment employés (YSZ) déposés par projection plasma (PS) ou en phase vapeur (EB-PVD), la présente étude a visé à mieux comprendre l’effet de l’évolution des propriétés microstructurales et chimiques des revêtements sur leur pouvoir isolant, dans le but de développer des outils nécessaires à la mise au point des revêtements du futur. De plus, une partie des travaux menés a porté sur une solution alternative plus économique et écologique d’élaboration de revêtements BT, fondée sur un procédé par voie barbotine, permettant in fine d’obtenir une barrière constituée de microsphères creuses d’alumine. Ce travail a permis de montrer que l’évolution par frittage des phases céramiques en YSZ, les changements de phase cristalline, les réactions avec les CMAS et la croissance d’oxydes thermiques modifient la diffusivité thermique. En revanche, celle-ci évolue moins avec la température puisque les revêtements en alumine issus de barbotines se sont avérés plus stables et ce, notamment, lorsque leur élaboration a été réalisée sous atmosphères hybrides (mélanges Ar/air)
In aeronautical gas turbine engines, the metallic materials employed in the hottest sections are subject to very harsh chemical environments at high pressures and temperatures. Therefore, thermal barrier coating systems (TBCs) are applied onto nickel-based superalloy substrates. These multi-layered systems (ceramic yttria-stabilized zirconia (YSZ) / MCrAl or NiPtAl bond coats / cooled substrate) lower the temperature at the components surface, which ensures an adequate thermomechanical behaviour and reduces the oxidation/corrosion rates. However, the increase of the turbine inlet temperature (increased engine performance) brings about new degradation phenomena (e.g. CMAS) and loss of efficiency of the current TBCs. Therefore, understanding the evolution of the insulation ability of TBCs in such harsh environments is key from both the scientific and technological perspectives to estimate the lifetime of these coatings, hence that of the engines. Based on current plasma-sprayed (PS) and electron-beam physical vapour deposited (EB-PVD) YSZ coatings, this thesis seeks to provide a better comprehension on the relationships between the intrinsic properties of the current TBCs and their thermal insulation capacity as a basis for the development of future coatings. Also, this work studies an alternative solution to create a TBC made of hollow alumina microspheres by the slurry route. We will show that the sintering of the YSZ, the evolution of crystal phases, the reactions between YSZ and CMAS and the growth of thermal oxides alter the thermal diffusivity to different extents. In contrast, the evolution of the thermal diffusivity with temperature is less marked with the slurry alumina coatings, which appear more stable when hybrid Ar/air annealing atmospheres are employed upon their synthesis

This investigation was done at NTNU and together with Statoil research and development department in Rotvoll, Trondheim to facilitate a new semi dynamic amine thermal degradation rig.This study was an initial attempt to investigate semi dynamic thermal stability rig as an alternative to thermal degradation study. The major purposes are: (1) to study MEA and MDEA thermal degradation by thermal stability rig apparatus which is designed by Statoil. (2) to demonstrate the result differences between the new and conventional experimental method. MEA and MDEA were selected in this study due to have more available literature data in amine based absorption process. The loaded liquid was circulated through the pipe from the cold stream to the hot stream. There is no analytical method was connected to the rig therefore a regular sample was taken every week and sent to SINTEF analytical lab to identify degradation products.Residence time of solution in high temperature zone also was calculated as an important factor in thermal degradation investigation. Different authors have been provided to understand: the background, the experimental set up, the analytical method to describe the degradation products, data interpretation and the mechanism of the degradation.Based on analytical results, it seems that only small portion of MEA and MDEA were degraded. It showed that the elapsed time was not enough to observe degradation in a significant amount. Metal qualification tests showed low metal concentration in solutions and generally very little corrosiveness effect. However, few degradation products were reported in this study the most probably degradation mechanism is estimated similar to suggested degradation pathway by Davis (2009). More works are required in future to better interpret the new thermal stability rig.

Given the importance of heat balance being maintained between a person and their environment an appropriate clothing choice is essential. Since military personnel are required to work effectively when deployed in any of the world's climates it is important that the thermal protection afforded by their clothing is considered as well as its more obvious protective properties such as those relating to the chemical and abrasive environments. Clothing descriptions restricted to details of heat and water vapour transfer characteristics alone, as is commonly the case, are recognised as being insufficient. Of particular note, where these data are obtained under 'artificial' conditions, ie intrinsic values, they are unlikely to represent the 'resultant' values as observed when worn by human subjects engaged in actual work tasks. Where intrinsic data are used in predictive standards calculations, to estimate safe work times etc, the workforce under consideration may not always be protected. One source of change in the thermal properties of clothing, when in the workplace, occurs due to increased convective and evaporative heat transfer at the wearer's skin surface caused by air movement through the clothing. This may occur as a result of wearer body movements or increased environmental air speed. The Ventilation Index has previously been suggested as an accurate and repeatable method for quantifying clothing ventilation characteristics. Although several other measurement techniques have also been suggested, the Ventilation Index is simple (albeit laborious) to conduct, and does not require the use of expensive equipment. Work conducted towards this thesis has shown that the Ventilation Index may be suitable for use in either manikin testing or human studies assessmentso f clothing. The aim of this thesis was to investigate the suitability of the Ventilation Index as a measurementt echnique for the assessmenot f clothing ventilation characteristics, particularly to consider the relationship between clothing ventilation and wearer physiological responses and to identify the factors which can affect this. The Ventilation Index measurement systems constructed as part of this research have improved on those used previously in similar research. New materials technology has provided an improved air-tight oversuit for use during measurement of the clothing micro-environment (a constant source of fiustration, it appears, for previous authors), while extensive calibration of the whole system has proved its accuracy. Using the Ventilation Index has shown that the ingress and egress of air into and from the clothing micro-environment may induce a physiological response from the wearer of the clothing (chapter 6) such increases in air movement being reflected by a drop in insulation afforded by the clothing (chapter 7). Of particular interest to persons involved in the thermal assessment of clothing, will be the suggestion that clothing may exhibit different ventilation characteristics when tested on a thermal manikin to when worn by human subjects. This difference appearing to be related to clothing fit (investigated in chapter 9). Of interest to wearer's of protective, is the observation that air-impermeable clothing does not necessarily withstand changes in environmental air movement (chapter 10). The technique is not without criticism. The standard tracer gas technique, used to calculate clothing air exchange rate, considers only air movement occurring next to the wearer's skin. In multi-layer clothing ensembles, the movement of air in clothing layers more distant will change the clothing micro-environment and thus have consequences for the wearer. Preliminary investigation suggests that distribution of nitrogen to each clothing layer should enable assessmenot fair movement in each of these layers.

The objective of this research was to quantitatively describe the the denaturation and aggregation processes of a-lactalbumin at neutral pH in order to understand their interrelationship and effect on solution stability. Three different preparations of a-La had similar denaturation temperatures, enthalpies and % reversibility as measured by differential scanning calorimetry. However, Native PAGE reveled three non-native monomer bands that corresponded to three distinct dimer bands indicating specific intramolecular disulfide bond shuffling leads to formation of disulfide-specific dimers. The apo protein was the most thermostable to turbidity development. The Ca-La was the most thermostable holo- preparation. Turbidity development at 95 degreesC (95 degrees C) indicated pure preparations intensely associate through hydrophobic interactions through bridging by divalent phosphate and this effect was mitigated by decreasing the ionic strength, decreasing the phosphate charge to ¡V1 (at pH 6.6) or decreasing the temperature. The aggregation behavior of a commercial a-La was investigated at neutral pH and 95?aC in a complex mineral salt environment to understand general stability factors involved in a nutritional beverage. The objective was to understand the effect of a-La lot variation, relative b-lactoglobulin concentration and excess calcium on the aggregate size development as measured by light scattering and turbidity development. The lot of holo-a-La possessing a higher intrinsic b-Lg concentration had higher solubility at pH 6.80, evolved more reactive thiol groups, had a 25% faster first order rate constant, dissociated only slightly with cooling and formed spherical aggregates with a much higher molecular weight. Aggregates intrinsic to the protein powder may play a role in aggregate growth and shape. Adding increasing quantities of b-Lg generally decreased solubility. The highest b-Lg concentrations investigated demonstrated a net thiol oxidation and, subsequently, had a diminished ability to aggregate through hydrophobic interactions. Adding excess calcium caused a dramatic loss of solubility at pH 7.0 and required an increase in pH to 7.5 to regain solubility.

Reliable and stable processes allowing precision manufacturing are a core demand in today’s production. To achieve stable processes several influences on machine tools have to be controlled. Beside the other factors, thermal influences are among the most important factors infecting the production system.In this work two problems that are caused by thermal deviations are considered: Firstly the positioning error of machine tools, and secondly possible changes in the elastic behaviour of a machine tool due to changes in stiffness.Positioning problems due to thermal changes are widely examined in research and the focus in this thesis is laid to a machine tool control program, developed and used by “Company A”, which will be explained and evaluated. This program is used both to evaluate new machine tools but also machine tools used in daily production. Also the standard method of Company A to compensate for thermal deviations in production is shortly evaluated.The connection between thermal deviations and changes in stiffness of a machine tool is a fairly new field in research. In this work tests were done using the Loaded Double Ball Bar (LDBB), a tool to measure the elastic behaviour of machine tools during movement. The changes observed in the machine tool are documented over time and different thermal states. A couple of machine tools of the same type but with different specifications are compared and differences and similarities are highlighted and evaluated.
Dagens produktion, som är sträver mot allt snävre toleranser och bättre precision kräver stabila och pålitliga processer. Flera faktorer som påverkar verktygsmaskiner måste kontrolleras för att nå en stabil process. Bredvid andra fakrorer har termiska förändringar en väldigt stor påverkan på produktions systemet.Det här arbetet undersökte två olika problem som framkallas av förändringen av termiska tillståndet, positionerings fel i verktygsmaskiner samt möjliga ändringar i maskinens styvhet.Termisk påverkan på positionerings felet av verktygsmaskiner är ett ämne som underöks av många forskare. Det här arbetet fokusserades därför på att undersöka ett program för att testa och kontrollera förändringar i verktygsmaskiner, framtagen av ett företag som kallas för ”Company A”. Själva programmet undersöktes och värderades. Programmet används av företaget både för att värdera nya maskina samt maskiner som används i daglig produktion. Dessutom undersöktes metoden av ”Company A” som används för termisk kompensering i daglig produktion.Sammanhanget mellan termiska förändringar och styvhet av en verktygsmaskin är ett någorlunda nytt forskningsämne. I det här arbetet utfördes tester med en Loaded Double Ball Bar (LDBB), ett verktyg som mätar elastiska egenskaper av en maskin under rörelse. Skillnader i maskinen som dokumenterades sattes i relation till tid och termiska förändringar. Några stycken maskiner av samma typ men med olika konfigurationer jämfördes och skillnader som likheter analyserades.

Multilayer insulation (MLI) has been shown to be the best performing cryogenic insulation system at high vacuum (less than 10[super]-3 torr), and is widely used on spaceflight vehicles. Over the past 50 years, many numerous investigations of MLI have yielded a general understanding of the many variables associated with MLI. MLI has been shown to be a function of variables such as warm boundary temperature, the number of reflector layers, and the spacer material in between reflectors, the interstitial gas pressure and the interstitial gas. Because conduction between reflectors increases with the thickness of the spacer material, and yet the radiation heat transfer is inversely proportional to the number of layers, it stands to reason that the thermal performance of MLI is a function of the number of layers per thickness, or layer density. Empirical equations that were derived based on some of the early tests showed that the conduction term was proportional to the layer density to a powe
ID: 029050581; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.A.E.)--University of Central Florida, 2010.; Includes bibliographical references (p. 79-85).
M.S.A.E.
Masters
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Aerospace Engineering

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1991.
Includes bibliographical references (leaves 82-83).
The validity of predictive models for the thermal conductivity of foam insulation is established based on the fundamental geometry of the closed-cell foam. The extinction coefficient is experimentally and theoretically determined; the theoretical prediction based on measured geometrical properties differed from the measured values by an average of 6% for ten different foams An approximate method uses measured geometrical values to adjust the measured diffusion coefficients of reference foams. The adjusted coefficients are used as inputs to a computer program which computes the effective thermal conductivity of the foam as a function of time. Values of effective thermal conductivity measured on laboratory and field samples are used as a standard for comparing the results of the physical models and the ageing program. Measured and predicted values differ by 11%, 13%, 1%, 5%, and 1% for the initial thermal conductivity of five foams tested. These errors decrease with time. The ageing program is used to simulate the time-averaged performance as a function of foam density, mean cell diameter, and fractional distribution of solid polymer. The results of the simulation indicate that for a 15 year service life, the optimal density is approximately 3 lb / ft3.
by John David Moreno.
M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 1997.
Includes bibliographical references (p. 66-69).
Insulation board is being fabricated and tested for use in developing countries. It is made at a low density, in the area of 5 to 10 pounds per cubic foot (80 to 160 kilograms per cubic meter), and has good thermal properties for an air based insulation, meaning R3 to R4 per inch (Btu-in/ hr-ft2-°F)-, or a conductivity of .048 to .036 W/m-K. The initial effort is to produce a straw insulation board suitable for northern Pakistan, where we are studying the needs and construction of schools and houses. Some type of rigid insulation is needed, as opposed to loose fill, because the buildings have solid masonry walls without an air gap. These boards will be suitable for other developing countries as well The initial survey of possible methods included 1) containing the straw in panels with wire and battens, 2) pulping the straw, and 3) binding with adhesive. In this latter category starch, PVA and sodium silicate were tried as adhesive using uncut and shredded straw, with various methods of application such as spraying, foaming, and dipping, at various adhesive loading rates. Small samples were formed at a range of densities to test structural and thermal properties. This survey suggested that all three of these approaches can succeed structurally and thermally, but that competing economically with existing insulation board is difficult. For boards with binder, the adhesive efficiency was poor. In the final phase of the project, a batch of boards was made at ICI Polyurethane's North American research and development facility, using methane di-isocyanate as the binder. The boards, made at a range of densities and resin contents, and using straw with and without the fine particles, were tested thermally and structurally at MIT. Good mechanical properties were obtained at resin contents as low as 2% by weight. At densities of 8 and 10 pounds per cubic foot (pcf), these boards have R values of 3.7 and 3.45 per inch, respectively. The pressure required to compress the 10 pcf boards to 10% of their original thickness is approximately 15 pounds per square inch (psi), and the modulus of rupture in bending is in the range of 50 psi. Removing the fine particles from the straw improved board strength markedly. These boards at a density of 10 pcf and 2 to 4 % resin content have an estimated materials cost of 2 [cents] per insulating unit (R-ft2), substantially less than either the cost of the expanded polystyrene available in Pakistan, or the retail cost of any rigid board insulation sold in North America.
by Henry S. Harvey, Jr.
S.M.

La tendència creixent a la indústria electrònica de fer aparells cada vegada més petits, més lleugers i que treballin més ràpid provoca un augment de calor generat per efecte Joule, degut a l’augment de freqüència del pas d’electrons. Eliminar aquest excés de calor requereix la millora de la conductivitat tèrmica dels materials ja existents, ja que el mantenir la temperatura de treball d’aquests dispositius està directament relacionat amb l’eficiència, el temps de vida útil i la prevenció de fallades prematures dels equips. Alguns elements dels dispositius electrònics es recobreixen amb reïnes termoestables epoxídiques. Per aquesta raó, augmentar la conductivitat tèrmica d’aquestes reïnes, aïllants per naturalesa, mantenint l’aïllament elèctric, resulta de gran importància en diverses indústries com l’electrònica i l’elèctrica. El mètode més senzill i econòmic per assolir aquest propòsit és mitjançant l’addició de partícules a la matriu polimèrica. En aquesta tesis doctoral s’han utilitzat diferents tipus de partícules per aconseguir els objectius en diverses matrius epoxídiques: nitrur de bor (BN), alúmina (Al2O3), nitrur d’alumini (AlN), carbur de silici (SiC), grafit expandit (EG) i nanotubs de carboni (CNTs). Experimentalment, s’ha determinat la influència que cada material afegit té sobre les propietats finals dels materials compostos, especialment de les característiques mecàniques, tèrmiques i elèctriques. El millor resultat obtingut pels objectius proposats ha estat la combinació del 70 % en pes de BN i un 2.5 i 5 % en pes de EG, arribant a més d’un 1600 % de millora en conductivitat tèrmica respecte el material de partida. Les conductivitats tèrmiques obtingudes han estat de 2,08 i 2,22 W/m·K, respectivament. A més, aquests materials han mantingut resistivitats elèctriques prou bones, al voltant de 10^10 i 10^6 Ω·m respectivament.
La tendencia de la industria electrónica de crear dispositivos cada vez más pequeños, más ligeros y que trabajen más rápido lleva a un aumento en la producción de calor generado por efecto Joule, debido al aumento de la frecuencia de paso de los electrones. Eliminar este exceso de calor lleva a la necesidad de mejorar la conductividad térmica de los materiales ya existentes, ya que limitar la temperatura de trabajo de los dispositivos está directamente relacionada con su eficiencia, su tiempo de vida útil y previene la aparición de fallos prematuros de los equipos. Algunos elementos de estos dispositivos están recubiertos de resina termoestable epoxídica. Por esta razón, aumentar la conductividad térmica de estas resinas, aislantes por naturaleza, resulta de gran importancia en varias industrias como la electrónica y la eléctrica. El método más simple y económico para alcanzar este propósito es mediante la adición de partículas a la matriz polimérica. En esta tesis doctoral se han utilizado diferentes tipos de partículas en varias matrices epoxídicas: nitruro de boro (BN), alúmina (Al2O3), nitruro de aluminio (AlN), carburo de silicio (SiC), grafito expandido (EG) y nanotubos de carbono (CNTs). Se ha determinado experimentalmente la influencia de cada material añadido en las propiedades finales de los materiales compuestos, especialmente en sus características mecánicas, térmicas y eléctricas. El mejor resultado obtenido en cuanto a los objetivos propuestos ha sido la combinación del 70 % en peso de BN y un 2.5 y 5 % en peso de EG, alcanzando más de un 1600 % de mejora en conductividad térmica respecto al material de partida. Las conductividades térmicas alcanzadas han sido de 2,08 y 2,22 W/m·K respectivamente. Además, estos materiales han mantenido unas resistividades eléctricas suficientes, alrededor de 10^10 y 10^6 Ω·m, respectivamente.
The tendency in electronics to produce smaller and lighter devices with higher power output causes an increase of the generated heat (Joule effect) by the increase in the frequency of electrons. Evolve this exceeding heat cause the need to improve some properties that existent materials do not meet, since keeping the working temperature of these devices is directly related to efficiency, useful lifetime and prevention of premature equipment failures. Some elements of these devices are coated by epoxy resins and this is the reason why enhance the thermal conductivity of them, insulators by nature, is of great importance in several industries such as electronics and electrical. The most economic and simple technique to face this issue is still today through the addition of high thermal conductive fillers. In this doctoral thesis, boron nitride (BN), alumina (Al2O3), aluminum nitride (AlN), silicon carbide (SiC), expanded graphite (EG) and carbon nanotubes (CNTs) have been used. Experimentally, the influence of each filler has been determined in the final composites, especially in the thermal, mechanic and electric characteristics. The materials with the best performances in the proposed objectives were those of homopolymerized cycloaliphatic epoxy resin with the combined addition of 70 wt. % of BN platelets and 2.5 and 5 wt. % of EG. The values of thermal conductivity improved by more than 1600 % in reference to the neat epoxy and were 2.08 and 2.22 W/m·K, respectively. These materials also kept enough electrical insulation, in the range of 10^10 and 10^6 Ω·m, respectively.

Thesis: S.M. in Building Technology, Massachusetts Institute of Technology, Department of Architecture, 2013.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 65-67).
Based on mounting evidence in support of anthropogenic global climate change, there is an urgency for developments in high-performance building techniques and technologies. New construction projects provide substantial opportunities for energy efficiency measures, but they represent only a small portion of the building stock. Conversely, while existing buildings are plentiful, they typically have a much narrower range of feasible energy efficiency options. Therefore, there will continue to be a need for the development of new and improved energy efficiency measures for new building construction and even more so for deep retrofits of existing buildings. This thesis provides an overview of the research performed into the on-going development at MIT of a high-performance panelized insulation system based on silica aerogel. Two test methods were used for measuring the thermal conductivity of the granules: the transient hot-wire technique and the guarded hot-plate system. Utilizing the hot-wire set-up, it was demonstrated that compressing a bed of granules will decrease the thermal conductivity of the system until a minimum point is reached around the monolithic density of the aerogel. For the Cabot granules, this was seen at 13 mW/m-K and about 150 kg/m3. The MIT granules showed equal performance to the Cabot granules at bed densities 20-30 kg/m3 lower. The hot-plate testing was able to experimentally evaluate previous analytical predictions regarding the conductivity impact of the internal panel truss and the under-prediction of radiant heat transfer in the hot-wire method. Hot-wire testing was also done in a vacuum chamber to quantify potential performance improvements at reduced air pressures. Since a vacuum would require the incorporation of a barrier film into the panel system, some analyses were done into the thermal bridging potential and gas diffusion requirements of such a film. Additionally, physical prototyping was done to explore how the film would be incorporated into the existing panel design. The aerogel-based insulation panel being developed at MIT continues to show promise, though there are still plenty of opportunities remaining in the development cycle.
by Adam Neugebauer.
S.M. in Building Technology

This thesis explores the hygrothermal performance of hemp insulation in the context of the United Kingdom. The key objectives of this investigation were to assess the heat and moisture management capacities of hemp insulations in two constructions typical to the UK, of timber frame and solid brick walls and to put the findings of the assessment into the greater context of conventional insulation materials by comparing hemp insulation’s performance with that of stone wool. The assessments were performed by means of laboratory-based experiments, in situ experimental monitoring and computer based numerical hygrothermal simulations. The most important finding during the laboratory-based experiment is that, in high relative humidity, the likelihood and frequency of interstitial condensation is higher in stone wool insulation than in hemp insulation. In terms of the material properties, one of the key findings during the laboratory-based experiment is the high level of moisture buffering capacities of hemp insulations, and therefore their potential in managing moisture in buildings. The in situ assessment of hygrothermal properties of hemp and stone wool insulations confirms the findings of the laboratory based experiments of the corresponding moisture management capacities of these two insulation materials. Parametric analysis of the in situ data shows that mould spore germination is possible in the insulations in vapour open walls although the visual observation has not confirmed the outcome of this analysis. In terms of thermal conductivity, the important finding is that the equivalent thermal conductivity of hemp and stone wool insulations are always equal or below the manufacturers’ declared thermal conductivity values. Long-term hygrothermal performances of hemp and stone wool insulation in timber frame and solid brick walls have been also assessed using a numerical hygrothermal simulation tool (WUFI). As far as the WUFI predictions are concerned, the application of the hemp or stone wool insulation on solid brick wall does not seem to be feasible with reference to condensation and mould growth in the insulations.

This master thesis project was performed in collaboration with Scania CV AB, Engine Materials group. The purpose with the project was to investigate different ceramic TBC (Thermal Barrier Coating) thermal insulation properties inside the combustion chamber. Experimental testing was performed with a Single-Cylinder engine with TBC deposited on selected components. A dummy-valve was developed and manufactured specifically for this test in order to enable a water cooling system and to ease the testing procedure. The dummy-valve consists of a headlock, socket, valve poppet and valve shaft. Additionally, a copper ring is mounted between the cylinder head and the valve poppet to seal the system from combustion gases. Thermocouples attached to the modified valve poppet and valve shaft measured the temperature during engine test to calculate the heat flux. The TBCs consisted of three different materials: 7-8% yttrium-stabilized zirconia (8YSZ), gadolinium zirconia and lanthanum zirconia. The 8YSZ TBC was tested as standard, but also with microstructural modifications. Modifications such as pre-induced segmented cracks, nanostructured zones and sealed porosity were used. The results indicated that the heat flux of 8YSZ-standard, 8YSZ-nano and 8YSZ-segmented cracks was in level with the steel reference. In the case of 8YSZ-sealed porosity the heat flux was measured higher than the steel reference. Since 8YSZ-standard and 8YSZ-sealed porosity are deposited with the same powder it is believed that the high heat flux is caused by radiative heat transfer. The remaining samples have had some microstructural changes during engine testing. 8YSZ-nano had undergone sintering and its nanostructured zones became fewer and almost gone after engine testing leading to less heat barrier in the top coat of the TBC. However, for 8YSZ-segmented cracks and gadolinium zirconia lower heat flux was measured due to the appearance of horizontal cracks. These cracks are believed to act as internal barriers as they are orientated perpendicular to the heat flow. During long-time (5 hour) engine tests the 8YSZ-standard exhibited the same phenomena: a decrease in heat flux due to propagation of horizontal cracks. One-dimensional heat flux was not achieved and the main reason for that was caused by heating and cooling of the shafts outer surface. However, the dummy-valve system has proven to be a quick, easy and stable to perform tests with a Single-Cylinder engine. Both water-cooling and long-time engine tests were conducted with minor issues. The dummy-valve has been further developed for future tests. Changes to the valve shaft are the most remarkable: smaller diameter to reduce heat transfer and smaller pockets to ensure better thermocouple positioning. Another issue was gas leakage from the combustion chamber through the copper ring and valve poppet joint. The copper ring will be designed with a 1 mm thick track to improve sealing, hence better attachment to the valve poppet.

Buildings consume more than 30 percent of the primary energy worldwide with 65 percent of this attributed to heating ventilation and cooling. To help address this, stratified concrete panels (SCP) have been developed to provide insulation without compromising the thermal mass of concrete. SCP is created by vibrating a single concrete mix containing heavy and lightweight aggregates. Vibration causes the heavy aggregates drop to the bottom so that two distinct strata are formed; an internal structural/heavyweight layer providing thermal mass and an external lightweight layer for insulation. SCP incorporates waste products, for both financial and environmental gains, from which technical benefits also result. Stratified concrete panels have been made and tested during past research projects with results suggesting that SCP could be a competitive product in the residential construction industry, an area in which precast concrete systems have not been favoured in New Zealand. Consideration has been given to the specific rheological requirements of the concrete mix design and the hardened properties of the finished panels. This research considers the commercial viability of SCP using an industrial setting. For practicality of the setting, some materials were altered from past laboratory work to materials that are more easily sourced and better understood but with similar properties as those used previously. Several panels were cast at Stahlton precast yard in an effort to optimise the production process. Consistent results were not achieved and a range of stratification levels were produced. This showed that some capital investment is required to commercialise SCP to provide more energy for vibration such that sufficient stratification can be reliably attained. Two panels were then stood up in an exposed area with the exterior facing north to test for warping effects in a practical setting. No measurable warping occurred over this time which concurred with past work and long term readings that were taken of four year old panels. Structural, thermal and durability tests were carried out on panels with a range of stratification levels to assess the sensitivity of these properties to the level of stratification. From this it was found that the panels with better stratification had significantly better thermal properties than those with moderate to poor stratification. Generally the thermal targets for this project were not met with the total thermal resistance (R-values) not meeting current code requirements. In some cases structural properties were improved with better stratification as the structural layer was stronger through better consolidation. Delamination potential increased with stratification and with age. This requires further research to minimise this effect using fibres across the layer boundary. Porosity was increased in the structural layer in the poorly to moderately stratified panels as the structural layer was not consolidated enough due to lightweight aggregate contamination. As with any new innovation, market acceptance is largely governed by public perception. With appropriate marketing as a sustainable energy saving product, SCP has the potential to be competitive in the residential construction market with some capital investment.

This research explores the thermal stability of ZrCrAlN material system. For this purpose fourteen different compositions of ZrCrAlN coatings were deposited onto tungsten carbide substrates by using reactive cathodic arc evaporation. These compositions were further annealed at 800oC, 900oC, 1000oC and 1100oC temperatures. EDS was employed to specify the compositions. The crystal structure of the coatings were analysed by XRD, and the hardness of these coatings was determined by Nanoindentation. The experimental findings reported a significant age hardening of Zr0.16Cr0.12Al0.72N and a delayed h-AlN formation in Zr0.07Cr0.40Al0.52N. ZrCrAlN was thus proved to be thermally stable.
Multifilms,A4:2 Growth and characterization of Multicomponent Nitrides by Magnetron Sputtering and Arc evaporation

Stability of biological substances based on proteins, including vaccines, antibodies, and enzymes, is critically linked to its thermal environment. Temperature stress over time results in protein denaturation. Denaturation is a loss of structure and function in proteins. Their storage and distribution therefore relies on a “cold chain” of continuous refrigeration, which is costly and not always effective in medical and biological applications. Due to this issue, access to insulin for treating diabetes is still beyond the reach of millions of people around the world [1]. Diabetes is predicted to be the 7th leading cause of death in the next decade [2].This project therefore sought to develop an innovative protocol of “ensilication” ef- fectively enclosing protein in a deposited silica “cage” to protect the protein from the denaturing process. To evaluate this aim, a release protocol involving treatment with a dilute solution of acidified NaF was designed to release the ensilicated proteins into solution. As test subject, covalently bonded sol-gel silica network was first exam- ined to surround lysozyme, then applied to haemoglobin, a heterotetrameric protein with a complex tertiary and quaternary structure. Remarkably, insulin is profitably ensilicated (80%) here along with a mediator, chitosan. The mechanism for the formation of protein ensilication was investigated using Syn- chrotron SAXS and DLS. The structures of ensilicated protein were confirmed using multiple microscopy and spectrometry methods. In order to test the product’s stabil- ity, the ensilicated protein was subjected to heating at 100 ◦C for hours or long-term ambient temperature storage. Analysis of the proteins released from their ensilica- tion with a wide range of methods including SAXS, ELISA, CD and FT-IR revealed that even after exposure to such extreme temperatures, the protein structure remains consistent with that of the native protein. The results demonstrate that the process produces a storable solid protein-loaded material directly from solution, and may thus be suitable for use with proteins that do not tolerate lyophilisation. Ensilication offers the prospect of a solution to the “cold chain” problem for biological materials, such as insulin.

This thesis is concerned with developing porous materials from tyre shred residue and polyurethane binder for acoustic absorption and thermal insulation applications. The resultant materials contains a high proportion of open, interconnected cells that are able to absorb incident sound waves through viscous friction, inertia effects and thermal energy exchanges. The materials developed are also able to insulate against heat by suppressing the convection of heat and reduced conductivity of the fluid locked in the large proportion of close-cell pores. The acoustic absorption performance of a porous media is controlled by the number of open cells and pore size distribution. Therefore, this work also investigates the use of catalysts and surfactants to modify the pore structure and studies the influence of the various components in the chemical formulations used to produce these porous materials. An optimum type and amounts of catalyst are selected to obtain a high chemical conversion and a short expanding time for the bubble growth phase. The surfactant is used to reduce the surface tension and achieve a homogenous mixing between the solid particulates tyre shred residue, the water, the catalyst and the binder. It is found that all of the components significantly affect the resultant materials structure and its morphology. The results show that the catalyst has a particularly strong effect on the pore structure and the ensuing thermal and acoustical properties. In this research, the properties of the porous materials developed are characterized using standard experimental techniques and the acoustic and thermal insulation performance underpinned using theoretical models. The important observation from this research is that a new class of recycled materials with pore stratification has been developed. It is shown that the pore stratification can have a positive effect on the acoustic absorption in a broadband frequency range. The control of reaction time in the foaming process is a key function that leads to a gradual change in the pore size distribution, porosity, flow resistivity and tortuosity which vary as a function of sample depth. It is shown that the Pade approximation is a suitable model to study the acoustic behaviour of these materials. A good agreement between the measured data and the model was attained.

The purpose of this project was to study Svenska Aerogel AB’s product Quartzene®, and develop its capacity as a thermal insulator. Quartzene® is a silica based mesoporous material developed by Svenska Aerogel AB, with properties similar to aerogels produced by the sol-gel process. In this report, the correlation between pore structure and thermal conductivity in the material has been studied using techniques, such as scanning electron microscopy, focused ion beam, finite element simulations and transient plane source. Its properties are interesting because of the expanding market of insulated vacuum panels; in which Svenska Aerogel AB wish to expand to. It was found that the pore sizes of M21-BU increased after compression, and the pore sizes of M4-0-2 decreased. The pore sizes of M21-BU became so large that the Knudsen effect is no longer of interest, and that could explain the different behaviors in thermal conductivity.

Vacuum insulation panels (VIPs) represent a high performance thermal insulation material solution offering an alternative to thick wall sections and large amounts of traditional insulation in modern buildings. Thermalperformance over time is one of the most important properties of VIPs to be addressed, and thus the ageing effectson the thermal properties have been explored in this work. Laboratory studies of ageing effects are conducted over a relatively limited time frame. To be able to effectivelyevaluate ageing effects on thermal conductivity, accelerated ageing experiments are necessary. As of today, nocomplete standardized methods for accelerated ageing of VIPs exist. By studying the theoretical relationshipsbetween VIP properties and external environmental exposures, various possible factors for accelerated ageing areproposed. The factors that are found theoretically to contribute most to ageing of VIPs are elevated temperature,moisture and pressure. By varying these factors it is assumed that a substantial accelerated ageing of VIPs can beachieved.Four different accelerated ageing experiments have been performed to study whether the theoretical relationshipmay be replicated in practice. To evaluate the thermal performance of VIPs, thermal conductivity measurementshave been applied.The different experiments gave a varying degree of ageing effects. Generally the changes in thermal performancewere small. Results indicated that the acceleration effect was within what could be expected from theoreticalrelationships, but any definite conclusion is difficult to draw due to the small changes. Some physical changes wereobserved on the VIPs, i.e. swelling and curving. This might be an effect of the severe conditions experienced by theVIPs during testing, and too much emphasis on these should be avoided.
Vakuumisolasjonspaneler (VIP) er en høyisolerende materialløsning som kan være et alternativ til tradisjonell bygningsisolasjon. På grunn av god isolasjonsevne kan man ved bruk av VIP redusere veggtykkelsen og fortsatt tilfredsstille energikravene som stilles til moderne bygninger. En av de viktigste egenskapene for VIP er evnen til å bevare høy termisk ytelse over tid. I den sammenheng har aldringseffekter for VIP blitt undersøkt. Siden laboratoriestudier av aldringseffekter gjøres i løpet av et relativt kort tidsrom, er akselerert aldring nødvendig for å få evaluert termiske egenskaper over tid. Det finnes pr. i dag ingen standardisert metode for akselerert aldring av VIP. Det finnes likevel flere studier av sammenheng mellom klimaforhold og VIP egenskaper. Spesielt er gass og fuktdiffusjon inn i panelet behandlet grundig i litteraturen. Basert på dette er det foreslått flere mulige faktorer for aldring av VIP. De faktorene som er funnet å bidra mest til aldring av VIP er temperatur, fuktinnhold i lufta og utvendig lufttrykk. Ved å variere disse faktorene er fire forskjellige aldringsforsøk beskrevet og gjennomført.Konduktivitetsmålinger er blitt brukt som et mål på de termiske egenskapene til de testede VIPene. De forskjellige forsøkene viste forskjellig grad av aldringseffekt. Generelt var endringen i konduktivitetsverdier liten. Resultatene indikerer at akselerasjonseffekten var innenfor hva som kan forutsies fra de teoretiske sammenhengene. Likevel er det vanskelig å trekke noen definitive konklusjoner, både siden endringen var så liten, og fordi få paneler ble brukt i forsøkene. Noen fysiske endringer ble observert under forsøkene. Blant annet este et av panelene noe ut, mens et annet bøyde seg permanent. Man burde likevel ikke legge for mye vekt på disse effektene, siden de kan skyldes de relativt ekstreme testforholdene.

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Neste trabalho é realizado um estudo da estabilidade de dutos enterrados submetidos a cargas térmicas. As cargas térmicas são devidas ao aquecimento do fluido com o objetivo de facilitar o transporte dos óleos que são escoados nos dutos. O duto expande devido a estas cargas térmicas. Como o duto está restringido em suas extremidades e devido à expansão são causadas forças axiais de compressão no duto. Para a análise destes dutos submetidos à variação da carga térmica foram utilizados modelos teóricos e numéricos para o problema de flambagem vertical e lateral, considerando o duto perfeito e com imperfeição. Os modelos numéricos foram desenvolvidos utilizando o programa ABAQUS. Para estes modelos numéricos o duto foi considerado como uma viga e a o solo como elementos de interface e elementos de mola. Foi desenvolvido também um modelo de viga-casca onde parte do duto é modelada como uma casca cilíndirca para permitir a análise de enrugamento e da deformação da seção transversal. São realizados estudos paramétricos numéricos para investigar o efeito do recobrimento do duto da forma e amplitude da imperfeição e da rigidez do solo na temperatura crítica de flambagem do duto.
In this work a study of the stability of buried pipelines subjected to thermal loads is developed. The thermal loads are due to the heated fluid that flows through the pipe. Fluid heating is for ease of oil transportation. The pipe expands due to the thermal loading. Axial forces are developed in the pipe due to the expansion since the pipe is restricted on its ends. The analysis of pipes subject to thermal loadas were carried out with use of theoretical and numerical methods for upheaval and snaking buckling problems considering perfect pipes and pipes with imperfection. The numerical models were developed with the support of the ABAQUS software. The pipe was modeled as a beam and the soil is represented by interface elements and alternatively by spring elements. A beam-shell model was also developed where part of the pipe was modeled as a shell to allow a wrinkling analysis. Parametric studies were also carried out to investigate the effects of the soil stiffness, shape and amplitude or the imperfection and internal pressure on the critical temperature of the pipe.

Nanocrystalline bainite, commonly known as “superbainite”, is a novel class of steel that utilises careful alloy design to reduce the bainite transformation temperature to below 300℃. This results in grains that are tens of nanometres in width, which make steel strong and tough. The structure can be produced in large volumes without the need for rapid cooling or severe deformation. The presence of austenite in nanocrystalline bainite is largely responsible for the toughness. Unfortunately, the austenite is metastable and previous work has shown that it decomposes into cementite and ferrite upon heating. This decomposition makes the material weak and brittle. The present work aims to develop new alloys that form nanocrystalline bainite, but which are able to survive heating. Previous work has shown that cementite precipitation is the first stage in the decomposition process and so the first alloys developed aimed to suppress cementite precipitation. This resulted in a noticeable improvement in thermal stability, although the austenite does eventually decompose at higher temperatures. Subsequent work led to an alloy which was designed not to resist cementite precipitation, but to tolerate it without the associated loss of austenite. This was achieved by the addition of large quantities of nickel to stabilise the austenite even if its carbon content is depleted. This alloy is able to survive exposure to elevated temperatures with the majority of austenite being retained. The thermal stability of the alloys was assessed using time-resolved synchrotron X-ray diffractometry at both the Deutsches Elektronen Synchrotron (DESY) and Diamond Light Source. The high-quality data that were collected allowed the symmetry of the ferrite lattice to be investigated and it was found that the lattice was best-described using a body-centred tetragonal crystal structure. This is the first evidence of its kind. Mechanical properties were investigated in the as-transformed condition at ambient temperature and at a temperature representative of aeronautic applications. The alloys developed in this project have comparable strength, toughness and fatigue performance to existing nanocrystalline bainitic steels. Mechanical properties were also measured after heating at 480℃ for 8 d and this was found to reduce strength and toughness, consistent with the measured loss of austenite.

This work is conducted on nanocrystalline nickel using a range of novel techniques in order to investigate the thermal stability of the microstructure and the mechanical properties of subsequent microstructures. Work is focused on two sources of nanocrystalline nickel produced via electrodeposition with varying levels of impurity sulphur. Impurity sulphur alters the thermal stability of the material; a low sulphur system is stable up to a temperature of 400°C and then coarsens normally to produce a micro-polycrystalline structure, a high sulphur material coarsens at 300°C and the coarsening quickly stagnates leaving a stable microstructure of rv550nm grains. Above 485°C, the high sulphur material is observed to undergo abnormal growth of large planar faceted grains. Observation of the growth post heat treatment via standard electron microscopy techniques gave statistical data complemented by in-situ heat treatment scanning electron microscopy and high temperature resistivity measurement tests to elucidate the stages of growth. A range of macro and micro scale tests were undertaken to investigate the physical properties of the materials; from Vickers hardness and four point bend, to novel in-situ micro-cantilever bend tests. The effect of the increased grain size from heat treatment leads to a reduction in the hardness and yield strength of the materials and in the case of the high sulphur material, segregation of the impurity to the grain boundary led to a ductile to brittle transition.

Metallic glass is a class of materials which have a disordered structure of atoms, due to this, glasses lack grains and grain boundaries, which are present in their crystalline counterparts. Metallic glasses have many interesting properties worth investigating, such as high corrosion resistance or high mechanical strength. However, metallic glasses are metastable and will therefore crystallise if heated above the crystallisation temperature. MoSiZr alloys have been studied and to gain knowledge of how the composition affects the crystallisation temperature, which enables further improvement of thermal stability. Crystallisation temperatures of the MoSiZr alloys were investigated by heat treatments in vacuum and ex-situ X-ray diffraction and X-ray reflectivity analysis. The highest thermal stability of the alloys was exhibited by M48Si48Zr4, Mo43Si50Zr7, Mo50Si40Zr10 and Mo45Si43Zr12, they remained amorphous after heat treatment at 1073 K. The resulting crystalline phases are Mo3Si, Mo5Si3 and ZrO2. Oxidation of Zr in the alloys is present only when the Zr content is at least 10 at%, crystallisation is otherwise mainly driven by formation of Mo3Si. Further improvement of the thermal stability is possible by introducing new alloying elements at the cost of those that promote crystallisation. Keeping the content of Zr below 10 at% is of great importance to prevent oxidation.

After extensive research during the last decades extruded polymeric insulation is now becoming an alternative to the traditional oil-paper systems for high voltage DC (HVDC) cables. Durability is of great importance for power cables, and the main purpose of this work has been to increase the knowledge of factors controlling the endurance of an extruded polymeric insulation under HVDC conditions. The effect of electrical and thermal ageing on electrical properties like space change accumulation, DC breakdown strength and electrical tree initiation has been investigated and related to changes in morphology, oxidation level and antioxidant concentration.

Low density polyethylene (LDPE) with and without an antioxidant additive was selected as insulating material. Test objects with plane electrodes or needle-plane electrodes were prepared by pressure moulding and equipped with aluminium electrodes. Iron particles with a diameter of 45 – 55 μm were introduced to simulate conducting contaminations in the insulation. The test objects were subjected to thermal ageing of 70°C and 90°C and the applied electrical field during ageing ranged from zero to 150 kV/mm. ageing was conducted both with constant DC polarity and with polarity reversals. The ageing period ranged from 4 weeks to 5 months.

Thermal oxidation was observed in LDPE without antioxidant and this clearly affected the electrical properties. The DC breakdown voltage was reduced by 40% and this was explained by enhanced high-field conduction and increased joule heating due to the oxidation products. It was found that oxidation was prohibited when the thickness of the aluminium electrodes increased.

Introduction of iron particles reduced the short term DC strength by 20 – 30%, but during long term ageing with constant DC voltage no difference was observed between test objects with and without particles. This was probably caused by screening of the particles by accumulated space charge.

The experiments showed that abrupt grounding or polarity reversal initiated electrical trees from the needle-electrodes. The longest trees were observed when the test objects had first been subjected to thermal and electrical ageing. The tree formation was caused by the high electrical field arising when the accumulated homocharge around the needle was converted to heterocharge at polarity or grounding,

The following main conclusions were made from the work:

*Oxidation is detrimental and must be avoided in HVDC insulation.

* The antioxidant additive can have a negative influence on the electrical properties under HVDC stress.

*Polarity reversal or abrupt grounding can initiate electrical trees from protrusions present at the electrode-insulation interface of a HVDC insulation system.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 169-177).
Aerogels are well known as exceptional thermal insulators. Thermal conductivities of 9 to 10 mW/m.K have been achieved at atmospheric pressure, and a moderate vacuum (between 1/3 and 1/10 of an atmosphere) can lower this number even further, to around 5 mW/m.K. However aerogels for insulation purposes are not widespread on the market. One of the major shortcomings of aerogels that prevent them from being more widely used is their extreme mechanical weakness and brittleness. In this thesis, we characterize and explain these low mechanical properties. We then propose a composite structure for a rigid aerogel panel, a sandwich panel with a truss core filled with monolithic aerogel. Mechanical and thermal properties are derived and partially tested for the truss cores. Several designs are studied and mechanical properties are derived in order to compare these designs. Some criteria for an efficient designs are given. Finally, we describe a first attempt to manufacture one of these composite structures on a small scale.
by Thomas Goutierre.
S.M.

碩士
國立雲林科技大學
環境與安全衛生工程系
104
An electric power system is composed of a generating system, transformation systems and distribution system. Among these, we have problems of a voltage drop due to long transportation. To cope with the problem of voltage drop, we need to site a transformer to address the specific problem. Therefore, in view of loss prevention the transformer is an essential piece of equipment in the electric power system. In practice, transformers are classified by heat dissipation, which consists of dry type transformer and oil immersed transformer. Numerous major accidents have been caused by oil-immersed transformers, with the main factor attributed to electric insulating oil (EIO) inside the transformer. In this study, we reviewed references about leakage accidents of these transformers to investigate whether the temperature could cause EIO to deteriorate. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to measure the thermal runaway excursion on EIO, and afterwards we performed voltage-endurance tests to detect the capacity of insulation in differential temperature. The study found that the insulation capacity of EIO was influenced by abnormally higher temperatures. When temperature was increased, insulating capability would be substantially limited. The result showed that when temperature was increased, the insulating capability of insulating oil would increase. Abnormally high temperature created problems of insulation deterioration, causing fire hazards or accidents of the oil immersed transformer. This caused the electric power system to be ineffective, which led to economic loss, catastrophes, even social outcry. Our study can provide information about inherent safety in utilization of oil immersed transformers, anticipate lower risk, and prevent leakage incidents of EIO from oil-immersed transformer, as an ultimate objective.

Dissertação de Mestrado Integrado em Engenharia Química apresentada à Faculdade de Ciências e Tecnologia
O objetivo deste trabalho é a síntese de aerogéis compósitos de alumina-sílica com incorporação de fibras para isolamento térmico a temperatura elevada. Recorreu-se à técnica sol-gel para a síntese dos aerogéis, utilizando-se como precursor e co-precursor de sílica o tetraetoxissilano (TEOS) e o viniltrimetoxissilano (VTMS), respetivamente, e para a modificação da superfície dos aerogéis o agente de sililação, hexametildissilazano (HMDZ). A formulação de base e os procedimentos de modificação da superfície e secagem foram otimizados no âmbito do projeto AeroXtreme, no qual esta dissertação se encontra enquadrada. A incorporação de alumina nos aerogéis foi feita recorrendo aos precursores cloreto de alumínio (AlCl3) e trissec-butóxido de alumínio (ATSB), mantendo constante a razão entre o número de moles de solvente e de precursores (S); uma parte do Si foi substituída por Al, variando a última entre 5 a 15 %mol. O reforço com fibras foi realizado utilizando polpa de aramida Kevlar®.A incorporação de alumina tem como finalidade melhorar a estabilidade dimensional a temperatura elevada (supressão da densificação dos aerogéis entre 600 e 800 °C) e da resistência mecânica dos aerogéis. A adição de fibras, por outro lado, impede o encolhimento durante a secagem, mantendo a elevada porosidade e melhorando a robustez mecânica dos aerogéis.Foi efetuada uma caraterização exaustiva dos aerogéis compósitos a nível físico-químico, morfológico, térmico e mecânico e os resultados obtidos permitiram uma discussão mais aprofundada do tema. Os ângulos de contacto variam de 139 - 162°, assim, todos os sistemas originam aerogéis hidrofóbicos. A introdução da fase de alumina na rede de sílica resulta em nanocompósitos com estruturas diferentes, dependendo do precursor utilizado. O diâmetro de poros varia entre 7,6 - 24,4 nm, estando os menores valores associados aos sistemas com ATSB. Pelo contrário, os sistemas com AlCl3 formam unidades estruturais maiores, mais porosas, com uma maior área superficial. A massa volúmica bulk apresenta valores entre 0,131 - 0,429 g/cm3 e o sistema que apresenta o menor valor é o sistema com base TEOS, 5 % de AlC3 e lavagem com etanol e heptano, devido ao seu menor encolhimento, 3,5 %. A condutividade térmica varia entre 29,9 e 68,5 mW/m K, sendo o valor mais baixo obtido com o sistema com AlCl3, e que foi o mais próximo dos aerogéis de sílica, cerca de 28 mW/m K. Após submetidas a temperaturas de 800 °C, as amostras apresentaram o resíduo final entre 78,7 - 90,0 %, concluindo-se que todos os aerogéis podem ser utilizados a essas temperaturas sem perder uma significativa percentagem de massa. No caso dos aerogéis com ATSB houve menos perda de massa do que com os restantes sistemas, indicando uma melhoria da estabilidade térmica com a introdução deste precursor. Por fim, a recuperação depois da compressão mecânica até 25 % de deformação varia entre 89,6 - 99,3 %. As amostras com ATSB introduzem mais rigidez na rede de sílica, logo apresentam resistência mecânica mais elevada do que as com AlCl3, isto é verificado quando comparamos, por exemplo, os valores mais elevados do módulo de Young que são de 6,93 MPa para o ATSB e 0,40 MPa para o AlCl3.
The objective of this work is the synthesis of alumina-silica aerogel composites with the incorporation of fibers for thermal insulation at elevated temperatures. The aerogels were synthesized by the sol-gel technique, being tetraethoxysilane (TEOS) and vinyltrimethoxysilane (VTMS) used as a precursor and co-precursor of silica, respectively, and hexamethyldisilazane (HMDZ) for the surface modification of the aerogel. The base formulation and surface modification and drying procedures were optimized within the scope of the AeroXtreme project, in which this dissertation is included. The incorporation of alumina in the aerogels was performed using aluminum chloride (AlCl3) or aluminum trisec-butoxide (ATSB) as precursors, keeping the ratio between the number of moles of solvent and precursors (S) constant; a part of Si was replaced by Al, the latter varying between 5 to 15 %mol.. Fiber reinforcement was performed using Kevlar® aramid pulp.The purpose of alumina incorporation is to improve the thermal stability and mechanical resistance of the aerogel. While the addition of fibers prevents shrinkage during drying, maintaining high porosity, and improving the mechanical strength of the aerogel.An exhaustive characterization of the composite aerogels was performed, including physico-chemical, morphological, thermal and mechanical properties and the results obtained allowed a deeper discussion of the theme. The contact angles vary from 139 - 162°, thus, all systems originate hydrophobic aerogels. The introduction of alumina phase resulted in different nanocomposite structures, depending on the precursor used. The pore diameter varies between 7.6 - 24.4 nm, the lowest value being associated with the ATSB systems. Oppositely, the systems with AlCl3 forms larger structural units, with higher porosity and higher specific areas. The bulk density values were between 0.131 - 0.429 g/cm3, the system with the lowest value is the one based on TEOS, 5 % AlCl3, which was washed with ethanol and heptane, due to its lower linear shrinkage, 3.5 %. The thermal conductivity is between 29.9 and 68.5 mW/m K, the lowest value being obtained with the system including AlCl3, which was closer to the value of pure silica aerogels, ca. 28 mW/m K. After being submitted to temperature treatment at 800 °C, the final residue ranges from 78.7 - 90.0 %, concluding that all aerogels can be used at these temperatures without losing a high mass percentage. For ATSB containing aerogels the mass loss was lower than for the other systems, indicating a higher thermal stability with the incorporating of this precursor. Finally, the recovery after mechanical compression until 25 % strain varies between 8.6 - 99.3 %. The samples with ATSB present higher stiffness, thus leading to higher mechanical resistance, when compared with those with AlCl3, this is verified when we compare, for example, the highest values of Young's modulus which are 6.93 MPa for ATSB and 0.40 MPa for AlCl3.

碩士
長庚大學
半導體產業研發碩士專班
95
In the thesis, thermal stability, the most concern in DRAM technology, of metal-insulator-metal capacitors was investigated. Post deposition annealing (PDA) in either N2 or O2 ambiance was performed. It was found that N2 PDA could condense bulk film and EOT decreased with the increasing PDA temperature. But the effect of O2 PDA only worked at 800oC. Post metal annealing (PMA) showed the opposite behavior to PDA which EOT was proportional to the PMA temperature. Meanwhile, the conduction mechanism of leakage current was also disclosed. Schottky emission dominated the leakage current under low electrical field and Poole-Frenkel conduction was responsible for leakage under high electrical field. The thermal stability was also verified by stress induced leakage current (SILC). Then, physical behavior induced by thermal annealing was revealed that oxidation of bottom electrodes was the major reason for electrical degradation which exhibited large surface roughness, thick interfacial layer, low capacitance, high leakage current, and undesired reliability. In order to suppress the oxidation induced by either ALD deposition or thermal process, an ultra-thin WN layer was embedded into the interface between bottom TiN electrode and Al2O3 layer as an oxygen barrier layer. MIM capacitors with WN layer showed less oxidation in bottom electrode, thus higher capacitance, lower leakage current and better reliability. Physical analyses including AFM, XRD and XPS were applied and confirmed the effect of WN layer. Therefore, it was believed that TiN/Al2O3/WN/TiN capacitor was most promising structure for DRAM application beyond 50nm technology.

Les infrastructures de transport est essentielle au maintien et à l'expansion des activités sociales et économiques dans les régions circumpolaires. À mesure que le climat se réchauffe, la dégradation du pergélisol sous les remblais a entraîné de graves dommages structuraux à la route, entraînant une augmentation importante des coûts d'entretien et une réduction de la durée de vie des infrastructures. Pendant ce temps, l'advection de chaleur déclenchée par les écoulements d’eau souterrains peut altérer le bilan énergétique du remblai et du pergélisol sous-jacent et modifier le régime thermique des remblais routiers. Cependant, peu de recherches ont été effectuées pour comprendre la synergie entre les processus thermiques de surface et souterrains des remblais routiers des régions froides. L'objectif de cette recherche était de comprendre les interactions thermiques entre l'atmosphère, le remblai routier, les écoulements d’eau et le pergélisol dans le contexte du changement climatique. Cette base, de connaissances est nécessaire pour la conception technique, l'entretien des routes et l'évaluation de la vulnérabilité des infrastructures. Les travaux de recherche ont permis de développer de nouvelles méthodes d'analyse thermique pour caractériser et identifier le rôle de l'advection thermique sur le changement de température d'un remblai routier expérimental au Yukon (Canada) en termes d’intensité, de vitesse et de profondeur de l'impact thermique. Les résultats montrent que l'augmentation de la température due aux flux de chaleur advectifs déclenchés par l’écoulement d'eau peut être jusqu'à deux ordres de grandeur plus rapide qu'en raison du seul réchauffement atmosphérique. La recherche a ensuite présenté un bilan énergétique de surface pour quantifier la quantité d'énergie entrant dans le centre et la pente du remblai avec des épaisseurs et des propriétés de neige variables. Le tout a été appuyé par des observations géothermique de plusieurs années et une grande quantité de données météorologiques. Les résultats illustrent que le bilan énergétique de surface est principalement contrôlé par le rayonnement net et moins par le flux de chaleur sensible. Le flux de chaleur transmis à la pente du remblai diminue de façon exponentielle avec l'augmentation de l'épaisseur de la neige et diminue de façon linéaire avec l’installation du couvert de neige et la longueur de la période d’enneigement. De plus, un modèle de bilan énergétique de surface et un modèle cryohydrologique entièrement couplé ont été développés pour étudier l'impact thermique de l'advection de chaleur associée à l'écoulement de l'eau souterraine sur le dégel du pergélisol et le développement de taliks (c.-à-d. zone perpétuellement non gelée dans les zones de pergélisol). Le modèle couplé a réussi à reproduire la tendance à la hausse du plafond du pergélisol (erreur absolue moyenne <0,2 m) au cours de la période 1997-2018. Les résultats montrent que l'advection de chaleur a fourni une source d'énergie supplémentaire pour accélérer le dégel du pergélisol et a doublé le taux d’augmentation de l’épaisseur de la couche active 0,1 m·a-1 à 0,19 m·a-1, par rapport au scénario où aucun écoulement d'eau ne se produit. Le talik s'est initialement formé et développé en fonction du temps sous l’effet combiné des écoulement d’eau, de l'isolation de la neige, de la construction de la route et du réchauffement climatique. Le débit d'eau souterraine a relié des corps isolés de talik et a amené le remblai de la route dans un état thermique irréversible, en raison de la rétroaction de l'eau liquide (effet de chaleur latente) piégée dans le talik. Ces résultats montrent l'importance de l'advection de chaleur induite par l'écoulement d'eau sur le régime thermique de la sous-couche (c.-à-d. la couche de matériau de remblai) et du sous-sol (c.-à-d. le matériau natif sous un remblai) du remblai lorsque le remblai routier intercepte le drainage local. De plus, les résultats obtenus soulignent la nécessité de coupler les processus thermiques de surface et souterrains dans le but d'évaluer la stabilité thermique des routes subarctiques.
Transportation infrastructure is crucial to maintaining and expanding the social and economic activities in circumpolar regions. As the climate warms, degradation of the permafrost causes severe structural damages to the road embankment, leading to large increases in maintenance costs and reductions in its lifespan. Meanwhile, heat advection triggered by mobile water flow can alter energy balance of the embankment and underlying permafrost and modify the thermal regime of road embankments. However, little research has been done to understand the synergy between surface and subsurface thermal processes of cold region road embankments. The overall goal of this research was to elucidate thermal interactions between the atmosphere, the road embankment, mobile water flow, and permafrost within the context of climate change. This knowledge is needed for engineered design, road maintenance, and infrastructure vulnerability assessment. The research first used new thermal analysis to characterize and identify the role of heat advection on temperature change of an experimental road embankment, Yukon, Canada in terms of magnitude, rate and thermal impact depth. It shows that soil temperature increase due to advective heat fluxes triggered by mobile water flow can be up to two orders of magnitude faster than due to atmospheric warming only. The research then presented a novel surface energy balance to quantify the amount of ground heat flux entering the embankment center and slope with varying snow depth and properties, supported by multi-year thermal and meteorological observations. My results illustrate that the surface energy budget is mainly controlled by net radiation, and less by the sensible heat flux. The ground heat flux released at embankment slope exponentially decreased with the increase of snow depth, and was linearly reduced with earlier snow cover and longer snow-covered period. A fully integrated surface energy balance and cryohydrogeological model was implemented to investigate the thermal impact of heat advection associated with subsurface water flow on permafrost thaw and talik (i.e., perennially unfrozen zone in permafrost areas) development. The integrated model successfully reproduced the observed increasing trend of the active layer depth (mean absolute error < 0.2 m) over the 1997-2018 period. The results show that heat advection provided an additional energy source to expedite permafrost thaw, doubling the increasing rate of permafrost table depth from 0.1 m·a-1 to 0.19 m·a-1, compared with the scenario where no water flow occurs. Talik formation and development occurred over time under the combined effect of subsurface water flow, snow insulation, road construction and climate warming. Subsurface water flow connected isolated talik bodies and triggered an irreversible thermal state for the road embankment, due to a local feedback mechanism (latent heat effect) of trapped, unfrozen water in talik. These findings elucidate the importance of heat advection induced by mobile water flow on the thermal regime of embankment subbase (i.e., a layer of fill material) and subgrade (i.e., the native material under an embankment) when the road embankment intercepts the local drainage. Furthermore, the obtained results emphasize the need to couple surface and subsurface thermal processes to evaluate the thermal stability of sub-Arctic roads.

Internal insulation in a solid rocket motor is a layer of heat-barrier material placed between the internal surface of the case and the propellant. The primary function of internal insulation is to prevent the rocket motor case from reaching temperatures that may endanger its structural integrity. An extensive experimental and theoretical work in the development and characterization of asbestos-free rubbers for use as rocket motor insulators has been performed. The insulation is based on chopped carbon fiber and/or aramid fiber in the pulp form as fillers for Ethylene Propylene Diene Monomer (EPDM). The first aim of the research is to provide an understanding of the mechanism, the principle, and the process for making polymeric thermal insulants. The second aim is to produce thermal insulants based on polymers with different fillers having different compositions which are capable of working under extreme thermal conditions of 2760 °C (5000 °F). This is through an investigation on the processing, installation, physical, mechanical, thermal and ablative properties of these materials. A hybrid of chopped carbon fiber and Kevlar pulp filled EPDM has been shown to exhibit better thermal, mechanical, physical and ablative properties than its asbestos containing counterpart. Also the prediction of thermal conduction of multiphase thermal insulation composite materials was done using series, parallel, Maxwell Euken and effective medium theory models. Comparison with the measured values allows determining which model estimates best the thermal conductivity of composite insulation material. Development of a suitable optimization technique to reach the best parameters of the selected material was done by doing transient dynamic analysis to determine the response of these materials under a time-varying thermal load. A new type of insulation material using prepregs was developed for the first time. This consists of the development of the prepregs and their assembly to make insulant laminates. This laminate has been shown to exhibit better physical, mechanical, thermal and ablative properties than a hybrid of chopped carbon fiber and Kevlar pulp filled EPDM.