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Sicner, Karen Maffitt. "A method for sizing flat plate solar collectors for space and hot water heating." Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/21750.
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Shin, Jong Gye. "Three-dimensional simulation of thermo elastic plastic plate bending by the line heating method." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14480.
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Filatov, Artem. "Concentrating Collector for Torsång District Heating System." Thesis, Högskolan Dalarna, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:du-28539.
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In this thesis report for Dalarna University in Borlange and Absolicon company the study of a possibility to add an array of concentrating solar collectors to a Torsång district heating system was done. The whole idea of this work was to make a simulation of this kind of system, trying to get 15-20% of solar fraction, and make an economical evaluation. At the same time, another goal was to make two comparisons: between concentrating and flat-plate collector in the same system, and between two tools for collector analysis – Polysun and Absolicon tool, based on TRNSYS, which was designed to estimate the output of the collector for a certain temperature, without any load. During the study, the analysis of the simulating tools was made and the combination of those two tools was used. Using long iteration cycles, involving changing the field layout, number of collectors and distance between collector rows in flat-plate collector case, both types of collectors were analyzed. The method of the analysis was to get an equal output of the field and see the differences, which appear while using different collector types.
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Deshpande, Dhananjay D. "Computer Modeling Of A Solar Thermal System For Space Heating." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1484142894264319.
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Elhabishi, Ali Mohamed. "Optimising collector plate geometry for a specific solar syphon system design." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2385.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016.Solar energy is still not being used effectively in countries in the developing world, though it's a partial solution to the problem of shortage and expensive energy. Normally harvested through flat plate collectors, converting solar radiation into heat is the most direct application that can be effected in water heating systems. Many researchers have attempted to develop means of improving the efficiency of the flat plate solar energy collector; however there appears to be no evidence of any work regarding the effect of geometric configuration on the performance of flat plate solar collector. This study presents results obtained when comparing the performance of a solar water heating system equipped with three manufactured flat plate solar collector panels of numerically identical surface area but of different geometric configuration as they were individually attached to a typical geyser. Data was obtained inside a laboratory. The amount of heat acquired from flat plate collectors of solar energy depends primarily on their surface area that is exposed to the solar irradiance, however, the geometry of the collectors was thought that it might affect to some extent the amount of heat harvested. The circulation of the water from the panel to the geyser was due to the self-induced thermo-syphon effect. The results obtained during the test period (7 hours per day for two consecutive days) indicated that the system’s thermal efficiency was best when the square geometrical configuration collector was used. A dimensional analysis using the Π Buckingham method that was performed on the parameters affecting a flat plate solar collector yielded three dimensionless numbers that lead to a power law relationship which might be useful in enhancing solar water heating systems’ design.
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Mahrabian, Mozaffar Ali. "Experimental, theoretical and computational modelling of flow in corrugated channels to investigate thermal and hydrodynamic characteristics of plate heat exchangers." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387964.
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Juřenová, Jana. "Návrh výběru druhu topných desek dle technologických a ekonomických aspektů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228308.
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Description and structure of the company. Description and characteristic of type of heating plates and heating medium. Analysis of the current selection of heating plates. Technological and economics aspects. Total estimation of aspects and suggestion of the best suitable alternate.
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Sari, Ozgur Gokmen. "Exergy Analysis Of A Solar Assisted Absorption Heat Pump For Floor Heating System." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12604765/index.pdf.
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Solar assisted single-stage absorption heat pump (AHP) was used to supply energy to a floor-heating system by using the exergy methods. An existing duplex-house,in Ankara, with a heating load of 25.5 kW was analysed. Heating loads of the spaces in the building were calculated and a floor heating panel was modelled for each space leading to the capacity of the AHP before it was designed. Solar energy was delivered to the evaporator and high temperature heat input delivered to the genarator are met by auxiliary units operating with natural gas.The solar energy gained by flat-plate collectors was circulated through AHP.The anaysis performed according to the storage tank temperature reference value if the water temperature leaving the storage tank exceeds a predetermined value it is directly circulated through the floor heating system.
Exergue analysis were carried out with Mathcad program. Exergy analysis showed that irreversibility have an impact on absorption system performance.This study indicated which components in the system need to be improved thermally.A design procedure has been applied to a water-lithium-bromide absorption heat pump cycle and an optimisation procedure that consists of determinig the enthalpy, entropy ,exergy, temperature, mass flow rate in each component and coeficient of performance and exergetic coefficient of performance has been performed and tabulated.
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Boehler, Michael David. "Transient Aerothermodynamics of Flow Initialization for a Flat Plate Film Cooling Experiment in a Medium Duration Blowdown Wind Tunnel Facility." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1284767673.
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Iordanou, Grigorios. "Flat-plate solar collectors for water heating with improved heat transfer for application in climatic conditions of the Mediterranean Region." Thesis, Durham University, 2009. http://etheses.dur.ac.uk/174/.
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The aim of this research project is to improve the thermal performance of passive flat plate solar collectors using a novel cost effective enhanced heat transfer technique. The project work focuses on the process of energy conversion from the collector to the working fluid. This is accomplished by employing an aluminium grid placed in the channels of a collector to induce a gradient of heat capacitance. This novel technique is tested both theoretically by means of simplistic designs using Computational Fluid Dynamics (CFD) and experimentally using two unglazed collectors. One collector has the aluminium net inserted in its channels and it is tested against an identical conventional collector in order to have a direct comparison at the same time. The obtained CFD data and the experimental findings are coupled and show a good agreement. All the obtained results are validated with the literature. The results both theoretical and experimental demonstrate an enhancement in the heat transfer coefficient by 9 % resulting to an increase in the output temperature of the working fluid in the collector with the metallic insertion. Other parameters such as the Nusselt and Raleigh numbers supported these findings. Three novel expressions that correlate the Nusselt and the Rayleigh number, for different heat fluxes, were developed using data from CFD and experimental results. These correlations can be applied on any flat plate collector with an aluminium grid in its pipes, in order to predict its performance. Furthermore an existing lumped parameters model that predicts the output temperature of a collector was simplified and improved.
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Hobbi, Alireza. "Design of solar water heating systems for cold climate and study of heat transfer enhancement devices in flat-plate solar collectors." Thesis, Connect to online version, 2007. http://proquest.umi.com/pqdweb?did=1394676661&sid=2&Fmt=2&clientId=10306&RQT=309&VName=PQD.
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Баглай, Назарій Ігорович, and Nazarii Bahlai. "Удосконалення конструкції пластинчастої пастеризаційної установки ОПЛ-10 для кисломолочних продуктів з дослідженням процесу теплообміну." Master's thesis, ТНТУ, 2020. http://elartu.tntu.edu.ua/handle/lib/33867.
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Захист відбувся 22 грудня 2020р. о 13.00 годині на засіданні екзаменаційної комісії №18В кваліфікаційній роботі пропонуються заходи з модернізації Удосконалення конструкції пластинчастої пастеризаційної установки ОПЛ -10 для кисломолочних продуктів з дослідженням процесу теплообміну при виробництві кефіру. Основними задачами, які вирішуються в даній кваліфікаційній роботі, є: аналіз конструкцій обладнання для пастеризації в молочній промисловості; технологічні, конструктивні, гідравлічні розрахунки установки ОПЛ -10; математичне моделювання гідродинамічних і теплообмінних процесів у каналах теплообмінника при виробництві кефіру; науково-технічні рекомендації щодо результатів досліджень; розробка заходів з охорони праціі та техніки безпеки; вирішення питань охорони праці та безпеки життєдіяльності
Анотація. Вступ. 1. Аналіз сучасного стану об’єкту дослідження, вибір і обґрунтування основних напрямків дослідження. 2. Методи та методика досліджень. 3. Розроблення нових технічних вирішень для модернізованої ППОУ. 4. Математичне моделювання технічної системи, що розглядається в роботі. 5. Охорона праці та безпека в надзвичайних ситуаціях. 5.1 Заходи з охорони праці. 5.2. Заходи з безпеки в надзвичайних ситуаціях. Висновки.
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Bendová, Martina. "Systémy se stěnovým vytápěním." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225560.
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This work deals with the topic "Systems with wall heating". On this theme is elaborated theoretical part. Further experimental part, which deals with the measurement of wall heating and comparing the results with the software CalA. Subsequently, this topic is applied to the specified building in which the wall heating, among other things dealt with. The project addresses the design of central heating, water heating, water heater design power units and air tempering lawn for future newly built free-standing facilities football club. The project is designed in two versions. In the first variant of the heat source heat pumps air-water. In the second variant is the heat source hot water pipe which is connected to transfer water-water station with plate heat exchangers.
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Yaser, Hussnain A. "Novel System Design For Residential Heating And Cooling Load Shift Using PCM Filled Plate Heat Exchanger And Auxiliaries For Economic Benefit And Demand Side Management." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1397234246.
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Farah, Hamad. "Hybrid solar system for heat and electric demands in a simple housing within Sweden and China." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-40596.
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The access to ideal heating and power techniques has always been highly thought after.This is mainly due to the development in housing architecture and the cold nature of certain regions which has led to an increase in popularity of the heating market and modernised heating technologies. The current DH systems make use of CHP plants for thegeneration of power and electricity. These CHP plants for the most part, are powered through biomass and during winter periods the demand for heating is highly increased.The biggest issue with relying on biomass solely is the constant need to burn wasteproducts which not only results in increasing the demand for consuming in more waste,but also results in producing remains (by-products) that cannot be broken down further and hence might require the utilization of land-space (landfills) for their disposal. Solar modules on the other hand, have gained increased popularity in the recent age. This is mainly due their extremely high flexible ability in converting solar irradiance intoelectrical and thermal energies. This study will try to provide a comprehensive study intothe utilization of a hybrid solar system that combines a standard PV module with a flat-plate collector through estimating the energy demands for a simple housing within Sweden and China. This will be the main aim of the study, however the possibilities of integrating this hybrid solar system alongside current DH systems will mostly be discussed in the first sections to proof the possibility of executing such a system. The theoretical work carried out will only include simulations of having just separate,standalone PV and flat-plate collector modules. However, designing a hybrid solar and DH system will not be the major focus of this study. The results at the end of the report,concluded that the electrical production for the Swedish case were noticeably higher thanthat of the Chinese case in spite of maintaining the same load values through both cases and higher solar irradiation for the Chinese case. Due to PVsyst simulation constraints,the results show that the investment cost of the Swedish PV (electrical component) module was about 3.6 times greater than that of the Chinese which could possibly mean that the Swedish case has a bigger PV module area than the Chinese case in order to meetel ectricity demand monthly. However, when it came to the thermal energy production, it was possible to assume different collectors cases and hence an area of 7m2 was chosen for the Swedish perspective while an area of 4m2 has been considered for the Chinese case. The thermal useful energy values where then compared with heating demands for both of the cases. Finally, the thesis concluded that there was no requirement for having an integrated DH network within the standalone houses, having small electricity and heat demand and hence, it might be more beneficial to have an integrated DH and solar system within more densely populated housing areas.Efterfrågan på tillgången till idealisk uppvärmning och effektiva tekniker har alltid varithög. Detta beror främst på utvecklingen inom arkitektur och den kalla naturen i vissaregioner som har lett till en ökad popularitet av värmemarknaden och moderniseradevärmeteknologiert. De nuvarande fjärrvärme-systemen använder kraftvärmeverk förproduktion av kraft och elektricitet. Dessa kraftvärmeanläggningar drivs till stor delgenom biomassa och under vinterperioderna ökar efterfrågan på uppvärmning mycket.Det största problemet med att förlita sig på biomassa enbart är det ständiga behovet avatt bränna avfallsprodukter som inte bara resulterar i att öka efterfrågan på konsumtionav fler avfallsprodukter utan också resulterar i att producera rester (biprodukter) sominte kan brytas ned ytterligare och därmed kan kräva användning av markutrymme fördeponering. solar-moduler å andra sidan har ökat popularitet under de senaste åren.Detta beror främst på deras extremt höga flexibla förmåga att konvertera solbestrålningtill elektrisk och termisk energi. Denna studie kommer att försöka tillhandahålla enomfattande studie av användningen av ett hybridsolsystem som kombinerar en standardPV-modul med en flatplate collector för att simulera en solar-modul samt caselera enfristående version genom att uppskatta energikraven för en enkel bostad i Sverige ochKina. Detta kommer att vara huvudmålet med studien, men möjligheterna att integreradetta hybrida solsystem tillsammans med nuvarande DH-system kommer mestadels attdiskuteras i de första avsnitten för att bevisa möjligheten att utföra ett sådant system. Detteoretiska arbetet som utförs kommer endast att innehålla simuleringar av att bara ha enfristående PV- och flatplate collector module, men att utforma ett hybrid sol- och DHsystemkommer inte att vara huvudfokus för denna studie. Resultaten i slutet avrapporten drog överraskande slutsatsen att den elektriska produktionen för den svenskacaselen var märkbart högre än den för den kinesiska caselen trots att de båda caselernabibehöll samma belastningsvärden och högre solbestrålning för den kinesiska caselen.Detta kan förklaras av skillnaden i modulpriser vid simulering genom PVsyst därinvesteringskostnaden för den svenska PV-modulen (elektrisk komponent) var ungefär3,6 gånger större än den för kinesiska, vilket innebär att PVsyst antar ett störremodulområde för svensk modul och därmed mer energiproduktion. Men när det kom tillvärmeenergiproduktionen, var det möjligt att anta olika samlarfall och följaktligen valdesett område på 7m2 för det svenska perspektivet medan ett område på 4m2 har beaktatsför den kinesiska och värmevärden för användbar energi där jämfördes sedan med dekrav som krävs för uppvärmning i båda fallen. Slutligen drog avhandlingen slutsatsen attdet inte fanns något krav på att ha ett integrerat DH-nätverk i de fristående husen ochdärför kan det vara mer fördelaktigt att ha ett integrerat DH och solsystem i tätarebebyggda bostadsområden.
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Fleming, Andrew J. "Aircraft Thermal Management Using Loop Heat Pipes." Wright State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=wright1238086423.
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Egerle, Dušan. "Kotelny na biomasu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226022.
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The aim of this project is heating and warm water preparation for apartment block in Choceň (Pardubice region). Apartment block has three aboveground heated floors and one underground unheated floor. The heat source is gasifying firewood boiler or pellet boiler which is at the same time used for water heating but only in the winter time. The other parts of the year the solar collectors are installed and used for water heating. The heat source is located in detached room with its own access, in boiler room.
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Anderson, Roger J. (Roger Jeffrey) 1976. "Experiments and simulation of line heating of plates." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80633.
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Qin, Jianbo. "Experimental investigation of bubble behaviours in domestic heat pump water heating system." Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/17662.
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The growing awareness of global warming potential has internationally aroused interest and demand in reducing greenhouse gas emissions produced by human activity. Each year, the UK consumes a significant amount of energy for residential and industrial space heating and domestic hot water production. At present, gas boilers are mostly installed in the domestic water heating which contributes significantly to excessive CO2 emissions and consumption of primary energy resources. However, air-source heat pump system has higher performance efficiency comparing to the traditional gas boiler, which can reduce the carbon dioxide emission and the usage of primary energy resources. The coefficient of efficiency of the heat pump can be range from 2 to 4.5 in various situations. The market shares of heat pump have been predicted to increase in the coming years to meet the requirement of the European Union Commission. There were about 22,000 heat pumps set up in the UK with 18 percent growth comparing to 2016 as reported by BSRIA. A range from 0.6 to 5.7 million heat pumps are estimated by the National Grid to be set up by 2030 to increase the energy efficiency of the UK. Although the energy efficiency of the heat pump is extremely high, there is still a space for improvement in air-source heat pump water heating system. The performance of the heat pump water heating system can be further enhanced if the dissolved gases in its hot water circuit can be efficiently discharged. The undissolved bubbles can stack in a specific position of the radiator, which would cause the cold spot. This could immensely reduce the efficiency of the heat pump water heating system. To avoid this happening, the bubble behaviors in the heat pump water heating system need to be extensively investigated. The better understanding of the bubble behaviors in an air-source heat pump water heating system can contribute to the design of an air evacuation valve and heat pump piping systems. In this thesis, the effects of various heat pump hot water side parameters on gas microbubble diameters and bubble productions were measured and analyzed by varying different experimental conditions. Correspondingly, a summarized conclusion has been presented to predict the gas microbubble's diameter distributions and volumetric void fraction distributions at different operating conditions. These parameters include various system pressures, water flow rates, and saturation ratios. In this thesis, the main results showed that larger average bubble diameter is at the higher water flow rates at heat pump exit. At 2.2 bar condition, when system water flow rate increased from 800 l/h to 1150 l/h, the average bubble diameter increased from 0.086 mm to 0.108 mm. Moreover, the average bubble diameters increase along with the decrease in system pressures. At 1000 l/h condition, when system pressure increased from 2.2 bar to 2.7 bar, the average bubble diameter decreased from 0.100 mm to 0.087 mm. At 850 l/h condition, when system pressure increased from 1.7 bar to 2.5 bar, the average bubble diameter decreased from 0.101 mm to 0.081 mm. In addition, the average bubble diameters slightly increase along with the increase in saturation ratio. Besides, a prediction equation for the bubble diameter distribution in the water pipe was proposed. At SR 1.15 and 2.5 bar condition, when water flow rate increased from 900 l/h to 1100 l/h, volumetric void fraction decreased from 2.25 E-05 to 4.83 E-06. However, at 1000 l/h and SR 1.15 condition, when system pressure increased from 2.2 bar to 2.7 bar, volumetric void fraction decreased from 2.16 E-05 to 3.78 E-06. It is found that the highest city main saturation ratio was achieved at 1.07 at the specific environmental condition.
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REINPOLD, LASSE MATTHIAS. "Analysis of Heating Processes for the Production of Bipolar Plates in PEM Fuel Cells." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-289622.
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Polymer electrolyte membrane fuel cells (PEMFCs) are a promising alternative to combustion engines and batteries in vehicles. PEMFCs are more efficient than combustion engines, and cars powered by PEMFCs tend to have longer ranges than battery powered cars and has a short fuelling time. To gain significant market shares, the costs of PEMFCs need to be reduced. This work aims to achieve this by improving the production process of bipolar plates, which significantly contribute to the total cost of fuel cells. In conventional production methods bipolar plates are formed by stamping at room temperature which limits the degree of deformation that can be achieved before exceeding the structural integrity of the material. It is expected that stamping at elevated temperatures will increase the forming limit of the material and therefore the flexibility in forming the channel geometry of bipolar plates. This has the potential to simplify the manufacturing process and improve the resulting performance of fuel cells. The goal of this thesis is to establish to what degree the forming at elevated temperatures facilitates higher degrees of deformation. Different heating methods are benchmarked and analysed numerically in order to identify the most suitable one for stamping experiments at elevated temperatures. Out of six investigated heating concepts, direct resistive heating is identified as the most suitable one. The suitability of the concept is supported by numerical simulations. The direct resistive heating system is designed and integrated into the existing experimental setup. Four flow channel geometries with channel widths of 1 mm, 0.8 mm, 0.6 mm, and 0.56 mm are investigated in stamping experiments using the identified heating method. Samples are formed at 150 °C, 300 °C, 600 °C, and 900 °C. Hexagonal Boron Nitride is used as a lubricant. The stamping experiments performed at elevated temperatures indicate that the formability of the bipolar plates improves as compared to the cold-formed reference experiments. The best results are obtained at 900 °C where the average channel depth, which can be formed before cracks are observed in the samples, could be improved by 27% compared to channels formed at room temperature.Polymerelektrolytmembranbränsleceller (PEMFC) är ett lovande alternativ till förbränningsmotorer och batterier i fordon. Fordon som drivs av PEMFC har en längre räckvidd än batteridrivna bilar och behöver bara några minuter för att tanka. PEMFC kan drivas utan utsläpp av växthusgaser. För att få betydande marknadsandelar måste tillverkningskostnaderna för dessa bränsleceller minskas. Detta kan uppnås genom att förbättra produktionsprocessen. Dessutom kan en förbättrad prestanda för bränslecellen leda till en minskning av storlek, materialanvändning och därmed produktionskostnader. Denna uppsats undersöker stämpling av metalliska bipolära plattor, som har en betydande del av kostnaden för en PEMFC. I konventionella produktionsmetoder bildas flödesfältgeometrin vid omgivningstemperaturer vilket begränsar den grad av deformation som kan uppnås innan materialets strukturella gränser överskrids. Det förväntas att stämpling vid förhöjd temperatur ökar formningsgränsen för materialet och därför flexibiliteten vid formning av kanalgeometrin. Detta förväntas förenkla tillverkningsprocessen och förbättra bränslecellens resultat. Målet med denna avhandling är att testa denna hypotes och fastställa hur förhöjda temperaturer underlättar högre deformationsgrader. För att uppnå detta används olika uppvärmningsmetoder som riktmärken och analyseras numeriskt för att identifiera den lämpligaste metoden för experiment med hetstämpling. Av sex undersökta värmekoncept identifieras direkt resistiv uppvärmning som den mest lämpliga. Konceptets lämplighet stöds av numeriska simuleringar. Det direktresistiva uppvärmningssystemet är utformat och integrerat i den befintliga experimentella installationen. Fyra olika kanalgeometrier undersöks. Prover bildas vid 150 ° C, 300 ° C, 600 ° C och 900 ° C. Hexagonal bornitrid används som smörjmedel. Stämplingsexperimenten utförda vid förhöjda temperaturer indikerar att de bipolära plattornas formbarhet förbättras jämfört med de kallformade referensexperimenten. De bästa resultaten erhålls vid 900 ° C där det genomsnittliga kanaldjupet, som kan bildas innan sprickor observeras i proverna, skulle kunna förbättras med 27% jämfört med formningen vid rumstemperatur.
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Buřič, Jan. "Vnitřní prostředí a výplně otvorů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-239950.
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The aim this diploma thesis is the design of heating and hot water in the building of a primary school in Trhové Sviny. The first part dealt with the issue of indoor environment and windows. The second part deals with a separate proposal heating and hot water in primary school. As a heat source was designed gas boiler, the second variant hot transfer station. The third part consists of technical reports and drawings of the specified object. The fourth part deals with the assessment of surface condensation on the surface of the window panes.
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Kotík, Libor. "Konstrukce sila na cukr." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227611.
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The matter of this thesis is static design and examination of prestressed storage tank to 50000 tons of sugar. Computational model of the steel roof structure is processed and its effect on the silos. Loads is provided of sugar. Optimal design is performed and assessment ultimate and serviceability limit state reinforced concrete and prestressing horizontal silo wall including local load. Next, it is performed the design of a reinforced concrete of the plane bed and column and assessment at the ultimate limit state. The thesis is also drawing documentation, technical report and visualization of construction process. The aim of this work is to the design of the main components based on the required storage capacity tank, mechanical properties of the stored material and technical amenities.
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Massard, Quentin. "Compréhension et maîtrise de la mise en oeuvre en fabrication additive d’aciers à haute teneur en carbone tel que le 100Cr6 par fusion sélective par laser sur lit de poudre." Electronic Thesis or Diss., Ecully, Ecole centrale de Lyon, 2022. http://www.theses.fr/2022ECDL0024.
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De nos jours, la production de pièces en acier par fabrication additive (FA) est un sujet central dans le monde de l’industrie, y compris l’automobile. En effet, les possibilités qu’offrent la fabrication additive sont diverses et nombreuses (allègement, formes complexes, …). Le 100Cr6 est un acier à hautes performances mécaniques, principalement utilisé pour la production de roulements à billes, en raison de son importante dureté et résistance à la fatigue. Une étude de processabilité de l’acier 100Cr6 par fusion selective par laser sur lit de poudre a tout d’abord été réalisée. Après avoir caractérisé les propriétés physiques et chimiques du matériau, des échantillons denses et non fissurés ont pu être produits au travers d’une optimisation paramétrique. Un cycle de post-traitement a pu être défini et des essais de traction plane et de fatigue par flexion rotative ont pu être réalisés.Afin de comprendre et maîtriser le phénomène de fissuration du 100Cr6 lors de son emploi par L-PBF une étude métallurgique approfondie (microdureté, imagerie optique, MEB, DRX, EBSD) a pu être menée. L’influence de l’emploi du plateau chauffant quant à la formation de Bainite et de Martensite et leur impacte sur la fissuration a pu être mis en évidence.Enfin, une étude de recyclabilité de la poudre de 100Cr6 oxydée a pu être réalisée à travers l’utilisation d’une machine de sphéroïdisation par plasma radiofréquence. Un débit d’alimentation de poudre dans le plasma permettant de régénérer les propriétés physiques et rhéologiques de la poudre a pu être défini. Une méthode de nettoyage permettant d’améliorer les propriétés chimiques de la poudre a également été proposéNowadays, the production of steel parts by additive manufacturing (AM) is a central topic in the world of industry, including automotive. Indeed, the possibilities offered by additive manufacturing are diverse and numerous (weight reduction, complex shapes, ...). 100Cr6 is a high mechanical performance steel, mainly used for the production of ball bearings, due to its high hardness and fatigue resistance. A processability study of 100Cr6 steel produced by selective laser melting on powder bed was first performed. After having characterized the physical and chemical properties of the material, dense and non-cracked samples were produced through a parametric optimization. A post-treatment cycle was defined and plane tensile tests and rotary bending fatigue tests were performed.In order to understand and control the cracking phenomenon of 100Cr6 when used in L-PBF, a thorough metallurgical study (microhardness, optical imaging, SEM, XRD, EBSD) was conducted. The influence of the use of the heating plate on the formation of Bainite and Martensite and their impact on cracking was highlighted.Finally, a recyclability study of the oxidized 100Cr6 powder was carried out through the use of a radiofrequency plasma spheroidization machine. A powder feed rate in the plasma allowing to regenerate the physical and rheological properties of the powder was defined. A cleaning method to improve the chemical properties of the powder was also proposed
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CASTRO, ALFREDO J. A. de. "Análise experimental de velocidade crítica em elemento combustível tipo placa plana para reatores nucleares de pesquisa." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/28022.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Os elementos de combustível de um reator nuclear de pesquisa tipo MTR (\"Material Testing Reactor\") são, em sua grande maioria, formados por placas de combustível revestidas com alumínio contendo no cerne silicileto de urânio (U3Si2) disperso em matriz de alumínio. Essas placas possuem espessura da ordem de milímetros e comprimentos muito maiores em relação à sua espessura. Elas são dispostas paralelamente no conjunto que forma o elemento combustível, de maneira a formar canais entre elas com poucos milímetros de espessura, por onde escoa o fluido de refrigeração (água leve ou água pesada). Essa configuração, associada à necessidade de um escoamento com altas vazões para garantir o resfriamento das placas em operação, pode gerar problemas de falhas mecânicas das placas de combustível devido às vibrações induzidas pelo escoamento nos canais e, consequentemente, acidentes de proporções graves no caso de velocidade crítica que possa gerar o colapso das placas. Embora não haja ruptura das placas de combustível durante o colapso, as deflexões permanentes excessivas das placas podem causar bloqueio do canal de escoamento no núcleo do reator e levar ao superaquecimento nas placas. Para este trabalho, foram desenvolvidas uma bancada experimental com capacidade para altas vazões volumétricas (Q=100 m3/h) e uma seção de testes que simula um elemento combustível do tipo placa com três canais de resfriamento. A seção de testes foi construída com placas de alumínio e acrílico e foi instrumentada com sensores de deformação, sensores de pressão, um acelerômetro e um tubo de pitot. As dimensões da seção de testes foram baseadas nas dimensões do Elemento Combustível do Reator Multipropósito Brasileiro (RMB), cujo projeto está sendo coordenado pela Comissão Nacional de Energia Nuclear - CNEN. Os experimentos realizados alcançaram o objetivo de chegar à condição de velocidade crítica de Miller com o colapso das placas. A velocidade crítica foi atingida com 14,5 m/s levando a consequente deformação plástica das placas que formam o canal do escoamento. O canal central na entrada da seção de testes apresentou uma abertura de 3 mm em seu centro, causando um grande bloqueio do escoamento nos canais laterais. Este comportamento foi v constatado visualmente durante a desmontagem da seção de testes, ilustrado e discutido na análise de resultados apresentado neste trabalho. O bloqueio dos canais também foi observado por meio de gráficos de queda de pressão e por gráficos das deformações da entrada, centro e saída das placas contra a velocidade média da seção de testes. Observou-se uma queda da resistência hidráulica da seção de testes devido ao aumento da seção transversal de escoamento no canal central e um aumento exponencial das deformações quando da ocorrência da velocidade crítica. Comparativamente, o valor experimental obtido para velocidade crítica na seção de testes foi da ordem de 85% do valor obtido por cálculo com a expressão teórica de Miller. Os experimentos realizados permitiram um melhor entendimento da interação fluido estrutura em elementos de combustível tipo placa como: valores de frequências de vibrações naturais, instabilidade fluido elástica e desenvolvimento de técnicas para a detecção de valores de velocidade crítica.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
CNPq:481193/2012-0
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Ni, Xianfeng. "Growth and characterization of non-polar GaN materials and investigation of efficiency droop in InGaN light emitting diodes." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2235.
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General lighting with InGaN light emitting diodes (LEDs) as light sources is of particular interest in terms of energy savings and related environmental benefits due to high lighting efficiency, long lifetime, and Hg-free nature. Incandescent and fluorescent light sources are used for general lighting almost everywhere. But their lighting efficiency is very limited: only 20-30 lm/W for incandescent lighting bulb, approximately 100 lm/W for fluorescent lighting. State-of-the-art InGaN LEDs with a luminous efficacy of over 200 lm/W at room temperature have been reported. However, the goal of replacing the incandescent and fluorescent lights with InGaN LEDs is still elusive since their lighting efficiency decreases substantially when the injection current increases beyond certain values (typically 10-50 Acm-2). In order to improve the electroluminescence (EL) performance at high currents for InGaN LEDs, two approaches have been undertaken in this thesis. First, we explored the preparation and characterization of non-polar and semi-polar GaN substrates (including a-plane, m-plane and semi-polar planes). These substrates serve as promising alternatives to the commonly used c-plane, with the benefit of a reduced polarization-induced electric field and therefore higher quantum efficiency. It is demonstrated that LEDs on m-plane GaN substrates have inherently higher EL quantum efficiency and better efficiency retention ability at high injection currents than their c-plane counterparts. Secondly, from a device structure level, we explored the possible origins of the EL efficiency degradation at high currents in InGaN LEDs and investigated the effect of hot electrons on EL of LEDs by varying the barrier height of electron blocking layer. A first-order theoretical model is proposed to explain the effect of electron overflow caused by hot electron transport across the LED active region on LED EL performance. The calculation results are in agreement with experimental observations. Furthermore, a novel structure called a “staircase electron injector” (SEI) is demonstrated to effectively thermalize hot electrons, thereby reducing the reduction of EL efficiency due to electron overflow. The SEI features several InyGa1-yN layers, with their In fraction (y) increasing in a stepwise manner, starting with a low value at the first step near the junction with n-GaN.
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Lee, Jau-Hung, and 李昭鴻. "Thermo-Mechanical Analysis of Plate Subject to Laser Heating Process." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/36496069913670503746.
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碩士國立成功大學
航空太空工程學系
86
The scope of the paper is to study the hot working forming process, utilizing the laser heating device moving along specific defined heating path, induced thermo-elastic-plastic deformation distribution problem for steel plate. Experimental tests and numerical analyses have been performed in order to investigate thermo-elastic-plastic deformation of steel plate after laser heating. Theoretical solution has been used to check against both the simulated and test finding for the simple steel plate in order to assure the accuracy and consistency. Commercially available finite element code (MARC) is used to investigate the deformation distribution of a piece of 10x10x0.1 cm3 steel plate under laser heating. Compare with the test finding for the steel plate and check the accuracy.Then identify the laser heating location and amount of heat flux generation utilizing neural network scheme based on deformation distribution measured from steel plate. The deformation distribution of various nodes on steel plate are used as the input data and the corresponding laser heating location and amount of heat flux are regarded as the output data in the neural networks. The time-domain back-propagation neural network with adaptive learning rate scheme is adopted in the present work. The trained network is capable of identifying the laser heating location and amount of heat flux generation for untrained cases closely.
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吳志庭. "Development and Testing on the Experimental Apparatus of Heating Plate." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/90890991725978984874.
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碩士國立屏東科技大學
機械工程研究所
83
This thesis aims to design and construct an experimental heating plate associating with the conjugate gradient optimization method for simultaneously measuring the thermal conductivity (k), thermal capacity per unit volume (C) and the thermal diffusivity (α) of samples. The theoretical simulation was implemented to study ideal measured points and locations. the results demonstrate that two measured temperature points which one point is located at heating plate and the other point is at 5mm to 20mm away from heating surface, lead to have good predicted results. As for the experimental measurement results of carrots, the deviation of k, C and α is respectively less than 6.26%, 6.73% and 11.17% froomthe literature.
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Chun, Yue-Haw, and 覃禹華. "A theoretical study on cold-plate performance with arbitrary heating loads." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/40162853606614484986.
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Jung, Inyeop. "Geometric location and power distribution for discrete heat sources on a vertical flat plate with natural convection." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-08-3750.
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The current development of consumer electronics, driven by the effort to manufacture smaller products with increased performance, has amplified the chance for inducing higher thermal stresses to these systems. In an effort to devise more effective cooling methods for these systems, many scholars have studied the convective cooling of discrete heating elements.
This report discusses a methodology for fabricating and testing a suitable flat plate design with discrete heating elements for both natural and forced convection cooling experiments. There were two plate design attempts: (i) an aluminum plate and (ii) a R3315 hydrostatic-resistance plastic foam plate. For the purpose of conducting experiments for the discrete heating elements, the foam plate design was found to be an appropriate design.
After designing a proper foam plate, several experiments were conducted for the natural convection case. The combination of parameters such as the geometric location and power output ratio between heaters that resulted in the maximum thermal conductance were studied.text
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Wu, Ssu-Han, and 吳思漢. "Fabrication Study on Poly-Si TFT for AMLCD with Heating Plate Crystallization." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/47500131822684414374.
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碩士國立雲林科技大學
電子與資訊工程研究所
93
In this thesis, discuss the different metal location effects the heating plate crystallization, the best way of the thermal energy transfer is bottom gate structure. By the way, different gate dielectrics may transport thermal energies with different rates. After the HPC process, the gate dielectrics will transport the thermal energy to the amorphous Si film, and recrystallizing the amorphous Si film into the poly-silicon film. However, if the gate dielectrics transports the thermal energy too fast, it will result in the film peeling problem. On the other hand, we also compare capping N+ layer and without capping N+ layer effect of the recrystallization. After HPC, We find that while capping N+ layer the crystallization temperature will reduce. The major reason of the recrystallization is bottom gate and N+ layer will absorb the thermal energy to enhance recrystallization. In the pattern effects the heating plate crystallization, we find that the thermal energy selectively absorbed by the gate patterns can be fully transferred to the pre-patterned Si active region. The energy of crystallization radiated from the gate electrode can then be fully transferred to the island-in Si active region and does not share with the other portions as in the conventional TFT structures.
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Po-ChitHuang and 黃柏齊. "Effects of surface roughness on natural convection flow above an inclined heating plate." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/16268990691874567268.
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碩士國立成功大學
航空太空工程學系
102
In this article, a numerical investigation is conducted to analyze the three-dimensional incompressible Navier-Stokes flows through the artificially roughened absorber plates in ventilation ducts. Several types of cross section（rectangle、arciform and equilateral triangle ）and different configurations of selected ribs（e/H = 0.06 - 0.2 and p/e = 1 - 7）have been used as roughness elements. The governing equations are solved with a finite-volume-based numerical method. The commercial finite-volume based CFD code ANSYS FLUENT is used to simulate airflow through artificially roughened absorber plates in ventilation ducts. It was found that equilateral triangular ribs give the better heat transfer augmentation than rectangular one. The induced air flow rate was evaluated in all range of parameters investigated and results suggested that induced flow rate in ducts with equilateral triangular ribs correspond to relative roughness height（e/H）of 0.1 and relative roughness pitch (p/e) of 3 is about 15.2 % higher as compared to smooth ducts.
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Hsieh, Hsieh-Shen, and 謝協伸. "Study of the deformation and vibration of a plate in pulsed laser heating." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/336nnz.
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碩士國立成功大學
機械工程學系碩博士班
90
Abstract The object of this thesis is to analyze the laser forming processing for a thin metal plate with the finite element method. The thesis was divided into two parts: one is the thermal deformation problem of the thin plates induced by thermal stress and the other is the vibration problem induced by thermal stress with a superposition method to reduce it. CO2 laser was used as a pulse energy source to heat the metal plates. The laser beam was focused on 304 stainless steel plates as a point heat source. In the analysis of the thermal deformation of the thin plates, the plate deformation was simulated numerically and verified experimentally. The non-linear finite element method software, ABAQUS, was used to simulate the deformation problem of the coupled thermal-mechanical system in three dimensions. The time-dependent temperatures, stresses, strains and bending angles during the forming process were calculated. The process parameters affecting the bending angles were also investigated. In the analysis of the vibration problem induced by thermal stress, the plate vibration was simulated and measured. The non-linear finite element method solved by ABAQUS, was used to simulate the thermo-mechanical problem in three dimensions. The time-dependent temperatures, and displacement during the process were calculated. The process parameters affecting the displacement were also investigated. There is a good agreement between the numerical simulation and the experimental observations in both studies of the plate deformation and vibration. A superposition method with multiple laser pulses was provided to reduce the plate vibration and it was verified with numerical and experimental approaches.
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Hsieh, Shu-Hui, and 謝淑惠. "Numerical Analysis of Heat Transfer in an Impinging Turbulent Jet on a Heating Plate." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/69879107928144732867.
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碩士國立交通大學
機械工程系
88
The heat transfer of a turbulent jet impinging on both normal and oblique heating plate had been investigated numerically. The temperature distribution and heat transfer in the flow field and the heating plate are solved simultaneously. The governing equations of this system are solved using the commercial software STAR-CD code. For the normal impinging jet, the local heat transfer coefficient as well as the mean Nusselt number are presented for the Reynolds number ranging 10000 to 110000 for L / D=2、6 and 10. Generally good agreement between the numerical results and experimental data is obtained in the present study. However, the heat transfer coefficient near the stagnation flow region is underestimated. The heat transfer can be well correlated by using Nu / Re^c as r / D greater or equal to 4 . Similar phenomenon is also observed in the experiments. Local heat transfer distributions from an obliquely impinging circular jet to a heating plate were obtained. Distribution of local heat transfer shows a non-symmetric pattern. The point of maximum heat transfer shifts from the geometrical impinging point toward the uphill plate。
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Chung, Yun-che, and 莊蘊哲. "Numerical simulation for natural convection on a vertical plate with equally spaced heating block." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/44173824521921988608.
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碩士國立中山大學
機械與機電工程學系研究所
99
The cooling problem has become a serious subject in order to keep away from malfunctioning for a high performance and miniaturized electronic component. For instance, the monitor backlight LED must be cooled adequately. In this thesis, a natural convection cooling problem for the vertical channel with equally spaced heating blocks on one wall is studied by a numerical modeling to simulate a monitor backlight LED cooling. A control volume method is employed for the numerical modeling. The results of heat transfer coefficients and hot spots for various channel gap, LED spacing and Rayleigh number are presented. This study can provide design reference for related cooling problems.
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He, Jyun-Wei, and 何峻瑋. "The Application of Moving Induction Heating in Roll-to-Plate Embossing for Microstructure Replication." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/72tdnk.
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碩士國立臺灣大學
機械工程學研究所
107
Traditional hot embossing is a popular technology for fabrication of polymer micro-structured components. It has the advantages of simple steps, high replication rate, and low cost. However, the traditional hot embossing employs plate-to-plate contact, inducing uneven pressure distribution. Moreover, it requires heating and cooling a whole hot plate which causes long cycle time and high energy cost. In this study, we used a roller to imprint the microstructure, combined with the mobile platform to increase embossed area and pressure uniformity. In order to prevent a film warpage from heat/cool effects, the induction heating facility and a platform with vacuum and water cooling were employed. To improve the temperature uniformity, the ferrite were placed in the induction coil as a field concentrator. The maximum temperature difference is less than 22 °C. Programming control has been used facilitate automated mobile induction heating imprinting equipment, reducing the human operational errors during the embossing process. The V-cut and microlens array microstructures were replicated on the 100×100 mm2 PC substrate. The replication rate can exceed 95%. The operation window was investigated. This study proves that the facility integrating induction heating and platform with vacuum and water cooling can be applied to the fabrication of polymer optical components with microstructure.
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Lai, Pei-Ching, and 賴佩青. "A Study on the Behavior of Adhesive Interface of theSteel Plate Reinforced Concrete After Heating." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/40320590576104927062.
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碩士國立臺灣科技大學
營建工程系
89
Nowadays, we lack the advanced study on the repaired and reinforced concrete under high temperature. Although those reinforced buildings can function properly under normal condition, but in case of fire the behaviors of these buildings are not well known. It is urgent needed to investigate further the behaviors and safety of such buildings. This project is intended to study the behaviors of the repaired and reinforced concrete specimens when they are subject to high temperature by tests in order to evaluate the influence of temperature and time of fire spreading on the safety. The experiment adopted the specimens which are commonly used methods in engineering practice presently such as steel plate reinforcement. The specimens will be subject to different temperature (room temperature, 50℃,100℃,150℃,200℃) and different durations (0.5hr, 1 hr, 2 hr, 3 hr) in the furnace. And then proceed with the following tests such as shear test, ultrasonic test in order to understand the properties at high temperature of the concrete, reinforcement material and the repaired structure respectively. By analyzing the data gained from the above tests, we can figure out the higher of shear strength of the solid adhesive layer, the less of sound-wave transmitting time and the faster of the wave transmitting velocity. The higher of the furnace temperature and the longer of the durations result in the apparent decrease of the shear strength. Owing to the high temperature, the fracture face doesn’t occur on the adhesive side of concrete but changes into the steel plate side. In other words, no sooner does the steel plate reinforced structures occur a fire than the fracture face is governed by the adhesive side of the steel plate.
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Lo, Hsin-Hsien, and 羅信賢. "Research on the Heating Mechanism of Xenon Lamp and Hot Plate for Semiconductor Manufacturing Reliability." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/884843.
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碩士國立交通大學
工學院半導體材料與製程設備學程
105
This paper presents the improvement of the flash lamp annealing (FLA) process to achieve the ultra-shallow junction (USJ) requirement for high performance CMOSFETs. Issues concerning ultra-rapid activation are discussed, namely, crystal damage (residual defect, deformation and crack) and pattern dependence. We report that the FLA process with about 1ms pulse duration can improve USJ characteristics for various design-scale cells. FLA is a technique for replacing the RTA used for activation after ion implantation extension and deep junction. In the conventional RTA, thermal diffusion will spread the source and the drain by, it cannot be applied to later 65nm device. Also, in the conventional RTA, it is not possible sufficiently reduce the resistance value. In FLA, after flash and immediately after ion implantation, it can be seen that the diffusion of ions is not almost happened. The spike anneal, indicating that even after more shallow ion implantation, the active layer widens after annealing. In Deep Junction is not Extension only can be applied. We present a systematic study on the plan for learning FLA Process reliability as following: To research the function for RS & Particle, stress monitor stable. To learning the relation process with Flash Annealing. To promote the wafer yield after Remain Particle issue be solved and also research the root cause of “Remain Particle issue”. To learning the analysis function (EX: Resistance & Stress value, PLi data, SIMS Profile, TEM data Particle count…etc.) to optimize FLA Process performance. Analysis the parameter that about Process & Hardware to improve defect recovery in FLA Processing. In this study, we found prior annealing technique is the limit. Temperature flash shines time of the wafer, is about 1ms, the temperature of the wafer is of rapidly decreasing the temperature at 1 ~ 3ms.Emission is only once, it is possible to sufficiently process the energy is high. The FLA Equipment and process will stable through the daily check by RS & Particle monitor, and the process reliability could be improved after we solved the issue of Sheet Resistance stability ,remain particle and wafer breakage issue .
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Kuo, Shih-Yi, and 郭詩毅. "The Change of Adhesive Properties of Epoxy Resin Materials used in Steel Plate Reinforced Concrete after Heating." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/94979478038507157860.
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博士國立臺灣科技大學
營建工程系
93
The steel plate reinforcement, which the steel plate providing the reinforcement strength for the application of daily service is bonded to concrete through the epoxy resin layer, is one of the most widely adopted strengthening techniques for damaged concrete structures. However, the safety issues of the repaired and reinforced concrete structures such as whether the epoxy resin can provide sufficient residual adhesive strength for maintaining the strengthen effects remain a question and need to be further studied in case of being subjected to fire attack or high temperature. In this research, non-destructive ultrasonic testing, FT-IR (Fourier Transform Infrared Spectrometer), SEM (Scanning Electron Microscopy) and OM (Optical Microscopy) were employed to analyze the changes of adhesive properties of epoxy resin layer after heating at different temperatures and durations to explore the subsequent influences on the safety of the aforementioned structures after heating. In addition, the non-destructive ultrasonic testing was adopted for quality evaluation of the structure elements after heating to avoid further damages to the structure examined. It is shown from the experiment results that the quality control of the process of injection and curing of epoxy resin layer of the steel plate reinforced concrete can be carried out by non-destructive ultrasonic wave measurement technique suggested in this research, and that the residual shear strength of the steel plate reinforced concrete decreases, while the transmission time increases, with increase of heating temperature and holding time. Degradation of adhesive layer resulted from pyrolysis of epoxy resin due to high temperature was found during FT-IR analysis, and fissures and voids generated in the interfaces were also observed in SEM and OM. The effects of pyrolysis of epoxy resin layer and degradation of the interfaces due to high temperature can deeply affect the residual shear strength of the adhesive layer of the steel plate reinforced concrete. As the adhesion of bonding layers and cohesion of epoxy resin decrease, the transmission time increases and the residual shear strength decreases. In application to the damage assessment of the steel plate reinforced concrete structure after a fire, the ultrasonic testing can be used to inspect the steel plate reinforced concrete to avoid further damage which destructive testing will cause and FT-IR analysis of epoxy resin samples can be utilized to estimate the residual shear strength and the highest temperature ever subjected to. The correct judgments concerning the safety of the strengthened structure after a fire can then be made.
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Chang, Chun-Yi, and 張鈞毅. "Effects of Top Plate Heating on Mixed Convection Vortex Flow of Air in a Bottom Heated Horizontal Flat Duct." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/38882453211557042688.
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碩士國立交通大學
機械工程系
89
An experiment combining flow visualization and transient temperature measurement is carried out here to study the possible stabilization and elimination of the buoyancy driven unstable longitudinal, transverse and mixed vortex flow in mixed convection of air in a bottom heated horizontal flat duct by the top plate heating. Systematic variations in the top plate temperature were performed to examine its effects on the spatial and temporal flow structures. How the top plate temperature and the Reynolds and Rayleigh numbers of the flow affect the vortex flow characteristics is investigated in detail. An open loop mixed convection apparatus established earlier was employed in this investigation and the test section is a high aspect ratio (A=12) rectangular duct. Experiment is conducted for the Reynolds number varying from 1 to 50, Rayleigh number from 4,000 to 8,000 and the nondimensional top plate temperature from 0 to 1 at an interval of 1/8, covering a wide range of the buoyancy-to-inertia ratio. The results from this study indicate that the top plate heating substantially stabilizes and eliminates the longitudinal, transverse, mixed longitudinal and transverse, and irregular vortex flows. It shows significant effects of stabilizing the vortex flow induced by the buoyancy resulting from the heated bottom plate of the duct. At the high top plate temperature even the entire irregular vortex flow can be eliminated and the flow is unidirectional in the duct. Obviously the transient flow oscillation in the flow is completely suppressed. An unfamiliar vortex structure consisting of stationary transverse rolls in the duct inlet and longitudinal rolls in the downstream is noted in the present study. They appear only at high buoyancy- to-inertia ratios. Various vortex flow patterns observed in the present study are summarized in Table 3.2.
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Kuo, Chuan-Feng, and 郭全豐. "A Study on the Behavior of the Steel Plate Reinforced Concrete with Externally Bonded Fireproof Coating Materials after Heating." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/91373963105968897728.
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碩士國立臺灣科技大學
營建工程系
90
Earthquake is frequent in Taiwan and structures are easily damaged from the earthquakes. Seriously damaged structures need to be dismantled, but strengthening methods can strengthen the lightly damaged structures. This study uses the most popular strengthening method- the steel plate reinforced concrete, but it can’t endure high temperature. So the fireproof coating material needs to be adhered to the steel plate in order to protect the integrity and durability of the structures. The objective of the study is to understand the relationship between the thermal energy absorbed by adhesive interface and the remained shear strength of the specimens after heating in order know the effects of fireproof coating materials and if the steel plates combine closely with concrete. The main testing variables of the study are the variations of temperature, rising temperature curves and fireproof coating materials. Thermal conductivity, DTA, GTA and temperature of the specimens are measured so as to realize the relationships of thermal energies. Study results show that the adhesive interface between 150℃~170℃ will suffer a loss of weight through the testing of TGA. No matter what kinds of rising temperature curves and whether fireproof coating materials are used, the relationships between the absorbed thermal energy and the remained shear stress in adhesive interface form two certain tendencies. The study also shows that when the temperature of the steel plate reinforced concrete is measured, the thermal energy can then be gotten through calculation; the remained shear stress and fracture modes can also be obtained by the equations from the tests.
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He, Juan. "Flavor comparison of ultra high temperature processed milk heated by Ohmic heating and conventional methods." Thesis, 2012. http://hdl.handle.net/1957/28661.
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Ultra high temperature (UHT) processing can extend shelf life of milk to several months without refrigeration, which is more convenient and energy saving than pasteurized milk. However, the poor acceptance caused by "cooked" flavors limits its marketing growth, especially in United States. Ohmic heating, which has a more uniform and rapid heating than conventional UHT process, may minimized the flavor change during the thermal treatment. Flavor composition between Ohmic heated UHT milk and other traditionally processed UHT milk (direct steam injection and indirect plate heating) during 36 weeks storage were investigated in this study. A total of 20 volatile compounds were analyzed based on their importance to UHT milk as well as their representation to different chemical classes including sulfur-containing compounds, ketones, lactones, aldehydes and others. Dimethyl sulfide (DMS) and methyl ketones were significant different among three types of UHT heated milk. δ-lactones showed higher amount in Ohmic heating after stored for four weeks, which might generate creamy, fruity intermediate aroma. Other compounds showed no significant difference among three heating processes. Aroma recombination test revealed that the overall aroma of the ultra pasteurized (UP) milk could be mimicked by recombining 15 important reference odorants in the same concentrations as they occurred in the UHT milk using commercial pasteurized milk as the matrix.Graduation date: 2012
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Lin, Ying-Zhi, and 林穎志. "Application of Induction Heating on Mold Surface to Enhance the Duplication of Light-guided Plate with V-groove Micro Structure." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/62806311166788849743.
Full textAbstract:
碩士國立高雄第一科技大學
機械與自動化工程所
97
The study aims to improve the injection molding of light-guided plate (LGP) with microstructure by applying induction heating coil which has the advantages of rapid and uniform heating. This study comprises of three parts: (1) to firstly find the optimal induction heating setting and to search an injection molding process window, (2) to generate the optimal molding parameters by using Taguchi method and ANOVA analysis, and (3) to proceed confirmatory experiment. By using an 2-inch light-guided plate as a research carrier to verify the performance of induction heating, the experimental results indicate that: (1) effect of duplicating the height of microstructure on LGP is significant as the mold surface temperature is heated from 110°C to 150°C. (2) Shrinking defect on the appearance of LGP is improved as the injection speed changes from 100 mm/s to 150mm/s. (3) LGP injection molding with the best parameter combination setting suggested by Taguchi method is stable in the confirmatory experiment.
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Lo, Chang-Chih, and 駱長志. "Transient Pool Boiling Heat Transfer of FC-72 and Associated Bubble Characteristics over a Small Horizontal Plate Subject to Time Periodic Heating." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/01452685635137129355.
Full textAbstract:
碩士國立交通大學
機械工程系所
96
Experiments are carried out here to investigate transient saturated and subcooled pool boiling of liquid FC-72 over a small horizontal copper surface subject to time-periodic heating, intending to explore how a time-periodic imposed heat flux oscillation in the form of a rectangular wave affects the FC-72 pool boiling characteristics. In the experiments, the mean imposed heat flux and amplitude of the imposed heat flux oscillation are respectively varied from 0.5 to 4.5 W/cm2 and from 0% to 100% with the period of the heat flux oscillation mainly fixed at 30, 60 and 120 seconds. The liquid subcooling is chosen to be at 5K and 10K. Both the time dependent boiling heat transfer and associated bubble characteristics will be examined. The measured data are presented in terms of the time variations of the space-average copper surface temperature and heat transfer coefficient for various mean levels, amplitudes and periods of the imposed heat flux oscillation. The experimental results indicate that the time-averaging boiling curves and heat transfer coefficients in the transient FC-72 saturated and subcooled pool boiling are relatively close to that for a constant imposed heat flux. Besides, the temporal variations of the space-average copper surface temperature, heat transfer coefficient, bubble departure diameter and frequency and active nucleation site density also oscillate periodically in time and at the same frequency as the time-varying heat flux imposed to the copper surface. Experiments also show that the resulting oscillation amplitudes of the copper surface temperature, heat transfer coefficient and bubble characteristics, such as dp, f and Nac, get larger for a longer period and a larger amplitude of the heat flux oscillation and for a higher mean imposed heat flux. Moreover, a short time lag in the copper surface temperature oscillation is also noted, which apparently results from the thermal inertia of the copper surface. The dimensionless time lag, which is defined as the actual ratio of the time lag to the period of the imposed heat flux oscillation, is larger at lower mean imposed heat flux, shorter period and higher amplitude of the imposed heat flux oscillation, and smaller liquid subcooling. Furthermore, when the mean imposed heat flux over the heated copper surface is slightly above the heat flux corresponding to that for the onset of stable boiling, intermittent boiling appears. The heat flux for the onset of the intermittent boiling for the present transient heating conditions is significantly higher than that for the stable boiling and the onset of boiling is earlier and the termination of boiling is later at a higher mean imposed heat flux or a longer period of the imposed heat flux oscillation. Finally, the effects of the imposed heat flux oscillation at extremely short and long periods are explored. Due to the existence of the thermal inertia of the heated copper block, the resulting heated surface temperature is close to that in the stable boiling at extremely short period of imposed heat flux oscillation. On the other hand, the space-average heated surface temperature gradually levels off and approaches a nearly stable state at each half cycle of the imposed heat flux oscillation for an extremely long period. As the imposed heat flux oscillates with time, the bubble departure diameter, departure frequency and the active nucleation site density also vary significantly with time. More specifically, the size of the departing bubbles, their departure frequency and active nucleation site density reduce in the first half of the cycle in which the imposed heat flux is at low level and the heated surface temperature decreases with time. While in the second half of the cycle an opposite process is noted since Tw increases with time. Moreover, the dp, f and Nac oscillations are stronger for higher mean level, larger amplitude and longer period of the heat flux oscillation.
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Ulerich, Rhys David. "Reducing turbulence- and transition-driven uncertainty in aerothermodynamic heating predictions for blunt-bodied reentry vehicles." Thesis, 2014. http://hdl.handle.net/2152/26886.
Full textAbstract:
Turbulent boundary layers approximating those found on the NASA Orion Multi-Purpose Crew Vehicle (MPCV) thermal protection system during atmospheric reentry from the International Space Station have been studied by direct numerical simulation, with the ultimate goal of reducing aerothermodynamic heating prediction uncertainty. Simulations were performed using a new, well-verified, openly available Fourier/B-spline pseudospectral code called Suzerain equipped with a ``slow growth'' spatiotemporal homogenization approximation recently developed by Topalian et al. A first study aimed to reduce turbulence-driven heating prediction uncertainty by providing high-quality data suitable for calibrating Reynolds-averaged Navier--Stokes turbulence models to address the atypical boundary layer characteristics found in such reentry problems. The two data sets generated were Ma[approximate symbol] 0.9 and 1.15 homogenized boundary layers possessing Re[subscript theta, approximate symbol] 382 and 531, respectively. Edge-to-wall temperature ratios, T[subscript e]/T[subscript w], were close to 4.15 and wall blowing velocities, v[subscript w, superscript plus symbol]= v[subscript w]/u[subscript tau], were about 8 x 10-3 . The favorable pressure gradients had Pohlhausen parameters between 25 and 42. Skin frictions coefficients around 6 x10-3 and Nusselt numbers under 22 were observed. Near-wall vorticity fluctuations show qualitatively different profiles than observed by Spalart (J. Fluid Mech. 187 (1988)) or Guarini et al. (J. Fluid Mech. 414 (2000)). Small or negative displacement effects are evident. Uncertainty estimates and Favre-averaged equation budgets are provided. A second study aimed to reduce transition-driven uncertainty by determining where on the thermal protection system surface the boundary layer could sustain turbulence. Local boundary layer conditions were extracted from a laminar flow solution over the MPCV which included the bow shock, aerothermochemistry, heat shield surface curvature, and ablation. That information, as a function of leeward distance from the stagnation point, was approximated by Re[subscript theta], Ma[subscript e], [mathematical equation], v[subscript w, superscript plus sign], and T[subscript e]/T[subscript w] along with perfect gas assumptions. Homogenized turbulent boundary layers were initialized at those local conditions and evolved until either stationarity, implying the conditions could sustain turbulence, or relaminarization, implying the conditions could not. Fully turbulent fields relaminarized subject to conditions 4.134 m and 3.199 m leeward of the stagnation point. However, different initial conditions produced long-lived fluctuations at leeward position 2.299 m. Locations more than 1.389 m leeward of the stagnation point are predicted to sustain turbulence in this scenario.text
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Hong-Lin, Ming, and 林明宏. "To study the heating temperature distribution uniformity of heating platen." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/35145827416523046412.
Full textAbstract:
碩士中州技術學院
工程技術研究所
97
The main goal of this thesis is to find out an optimal arrangement of the heating pipe of a rubber injection molding machine (RTIP150 Y10), so that the temperature distribution of heating platen is uniform enough. In order to regulation the temperature of heating platen, controller technique is often used to achieve the goal of uniform temperature distribution. However, the arrangement of heating pipe is actually depended on experience only. Due to the situation stated above, two improvement approaches are provided in the thesis. At first, the orthogonal table L9 of Taguchi Method is used to implement a numerical simulation experiment. The temperature distribution obtained by simulation are then used to find out the optimal combination of parameter and then verified by an actual experiment. At second, the optimal design parameters of heating platen which is obtained through Taguchi Method are used as the initial guess of an optimization procedure. Then the length and power of electric heating pipes are determined by a steady state optimization written by ANSYS. The experiment results of top surface temperature difference show by Taguchi Method was 7.9℃, and simulation result was 7.1℃; Besides show from 9 fixed point, top surface temperature difference of the experiment was 5.4℃, and simulation result was 4.2℃. Through the results of optimization analysis, the temperature difference of top surface can be reduced to 0.8℃.The experiment temperature difference of top surface is 1.8℃ by used the new electric heating tube from simulation result. Besides show from 9 fixed points, top surface temperature difference of the experiment was 1.6℃, and simulation result was 0.5℃ it has already significantly improved preliminary design. ANSYS optimization analysis method can effectively improve the heated plate temperature uniformity, which helps to improve rubber injection molding machine of the molding quality.
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Tai, Ning-Sheng, and 戴寧生. "The Application of Rapid Mold Heating Method to Molding Light Guide Plates." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/25582725122870755742.
Full textAbstract:
碩士國立高雄第一科技大學
工程科技研究所
95
This work employs the combination of mold temperature heating and induction heating methods to achieve rapid surface heating. It is beneficial to increase the replication of micro features on light guide plates. A two-inch light guide plate is used for experimental verification in this research. First, the ability and efficiency of the rapid surface heating is assessed for the electromagnetic induction heating. Thereafter, the replication of the electromagnetic induction heating will be compared with the conventional oil heating. The experimental results show that: (1) a planar induction coil has an advantage of rapid heating the surface of the mold-insert. (2) The replication of the micro features of the light guide plate in accordance with the steps of heating to 80℃ by using oil heating and then simultaneously heating to 110℃ by using planar induction coil, will be reached to 95%. It demonstrates the ability of producing higher replication than that of conventional oil heating. (3) There is no obviously residual stress distribution appeared in molded light guide plate. (4) The cycle time of using the induction coil heating is one third times of the conventional oil heating, due to the shortening of cooling time.
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Janca, Larry Lee. "Removal of out-of-plane distortion in mild stell panels using flame heating." Thesis, 1987. http://hdl.handle.net/10945/22456.
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Peng, Tzu-En, and 彭梓恩. "Natural convection between vertical parallel plates with asymmetric heating at high aspect ratios." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/41190288628204544018.
Full textAbstract:
碩士國立交通大學
機械工程系所
103
An unsteady flow reversal of natural convection in vertical parallel plates with an asymmetrically heated wall is investigated numerically. For clarifying the occurrence of flow reversal, the width of the plates is regarded as a variable, and the non-reflecting boundary condition is adopted at apertures. The methods of the Roe scheme, preconditioning and dual time stepping matching LUSGS are simultaneously used to solve governing equations which are available for a low speed compressible flow problem. The flow reversal is observed under broad width situations and absent under narrow width situations. Distributions of the pressure differences at the apertures are revealed to indicate the occurrence of flow reversal. As the width of the parallel increases, the flow reversal will form the flow downward-penetration through the inlet. The present Nusselt numbers, which mean time and area-averaged ones, display relatively good agreement with those of the existing works.
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Kumar, Chintoo Sudhiesh. "Experimental Investigation Of Aerodynamic Interference Heating Due To Protuberances On Flat Plates And Cones Facing Hypersonic Flows." Thesis, 2013. http://etd.iisc.ernet.in/handle/2005/2621.
Full textAbstract:
With the age of hypersonic flight imminent just beyond the horizon, researchers are working hard at designing work-arounds for all the major problems as well as the minor quirks associated with it. One such issue, seemingly innocuous but one that could be potentially deadly, is the problem of interference heating due to surface protuberances. Although an ideal design of the external surfaces of a high-speed aircraft dictates complete smoothness to reduce drag, this is not always possible in reality. Control surfaces, sheet joints, cable protection pads etc. generate surface discontinuities of varying geometries, in the form of both protrusions as well as cavities. These discontinuities are most often small in dimension, comparable to the local boundary layer thickness at that location. Such protuberances always experience high rates of heat transfer, and therefore should be appropriately shielded. However, thermal shielding of the protrusions alone is not a full solution to the problem at hand. The interference caused to the boundary layer by the flow causes the generation of local hot spots in the vicinity of the protuberances, which should be properly mapped and adequately addressed. The work presented in this thesis aims at locating and measuring the heat flux values at these hot spots near the protrusions, and possibly formulating empirical correlations to predict the hot spot heat flux for a given set of flow conditions and protrusion geometry.
Experimental investigations were conducted on a flat plate model and a cone model, with interchangeable sharp and blunt nose tips, with attached 3D protuberances. Platinum thin-film sensors were placed around the protrusion so that the heat fluxes could be measured in its vicinity and the hottest spot located. These experiments were carried out at five different hypersonic free stream flow conditions generated using two shock tunnels, one of the conventional type, and the other of the free-piston driven type. The geometry of the protrusions, i.e., the height and the deflection angle, was also parametrically varied to study its effect on the hot spot heat flux. The results thus obtained for the flat plate case were compared to existing correlations in the open literature from a similar previous study at a much higher Reynolds number range. Since a mismatch was observed between the results of the current experiments and the existing correlations, a new empirical correlation has been developed to predict the hot spot heat flux, that is valid within the range of flow conditions studied here. A similar attempt was made for the case of the cone model, for which no previous correlations exist in the open literature. However, a global correlation covering the entire range of flow conditions used here could not be formed. A correlation that is valid for just one out of the five flow conditions used here is presented for the cones with sharp and blunt nose tips separately.
Schlieren flow visualization was carried out to obtain a better understanding of the shock structures near the protuberances on both models. For most cases, where the protrusion height and deflection angle were large enough to cause flow separation immediately upstream of the protuberance, a separation shock was manifested which deflected some part of the boundary layer above the protuberance, while the rest of the fluid in the boundary layer entered a recirculating region in the separated zone before escaping to the side. Some preliminary computational analysis was conducted which confirmed this qualitatively. However, the quantitative match of surface heat flux between the simulations and experiments were not encouraging. Schlieren visualization revealed that for the flat plate case, the foot of the separation shock was located at a distance of 10.5 to 12 times the protrusion height ahead of it, whereas in the case of the sharp cone, it was at a distance of 9 to 10.5 times the protrusion height. The unsteady nature of the separation shock was also captured and addressed. Some preliminary experiments on boundary layer tripping were also conducted, the results of which have been presented here.
From this analysis, it has become evident that a single global correlation cannot be formed which could be used for a wide range of flow conditions to predict the hot spot heat flux in interference interactions. The entire range of conditions that may be encountered during hypersonic flight has to be broken down into sections, and the interference heating pattern should be studied in each of these sections individually. By doing so, a series of different correlations can be formed at the varying flow conditions which will then be available for high-speed aircraft designers.
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Chiou, Yih Ming, and 邱奕銘. "Pre-Processor and Post-Processor Development for Multi-Layer Cold Plates with Arbitrary Heating Loads." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/10901499118710416466.
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