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Relevant bibliographies by topics / Passive thermal control

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Academic literature on the topic 'Passive thermal control'

Author: Grafiati

Published: 28 June 2021

Last updated: 7 February 2022

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Journal articles on the topic "Passive thermal control"

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TSUTSUI, Fumiya, Toshiyuki SHISHIDO, Tatsuya SATO, Hiroyoshi ONO, and Kentaro SHOJI. "Passive Thermal Control of Pressurized Modules of JEM." Proceedings of the JSME annual meeting 2000.4 (2000): 543–44. http://dx.doi.org/10.1299/jsmemecjo.2000.4.0_543.

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Venneri, Paolo F., Michael Eades, and Yonghee Kim. "Passive Reactivity Control of Nuclear Thermal Propulsion Reactors." Nuclear Technology 197, no. 1 (January 2, 2017): 64–74. http://dx.doi.org/10.13182/nt16-80.

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Omar, M., and Y. Zhou. "Automotive Production Control, Using Thermal Vision Systems – A Passive Thermal Imagery for Process Control." SAE International Journal of Materials and Manufacturing 1, no. 1 (April 14, 2008): 279–84. http://dx.doi.org/10.4271/2008-01-0681.

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Aggogeri, Francesco, Alberto Borboni, Angelo Merlo, and Nicola Pellegrini. "Machine Tools Thermostabilization Using Passive Control Strategies." Advanced Materials Research 590 (November 2012): 252–57. http://dx.doi.org/10.4028/www.scientific.net/amr.590.252.

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The aim of this study is to investigate passive control strategies using Phase Change Materials in Machine Tools (MTs) thermostabilization. By considering the main issues related to the thermal stability, authors presented the application of novel multifunctional materials to Machine Tools structures. A set of advanced materials are considered: aluminium foams, corrugate-core sandwich panels and polymeric concrete beds. The adopted solutions have been infiltrated by phase change materials (PCMs) in order to maintain the thermal stability of MTs when the environmental temperature is perturbed. The paper shows the results of simulative and experimental tests.

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Bivolarova, Mariya, Arsen Melikov, Tereza Snaselova, and Chong Shen. "Passive Control Of The Bed Micro-Environment By Quilts." E3S Web of Conferences 111 (2019): 02064. http://dx.doi.org/10.1051/e3sconf/201911102064.

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An easy method to passively control the bed micro-environment and thus thermal comfort of people is to use a cover with appropriate thermal insulation. The purpose of this study was to find out the potential of generating uniform and non-uniform bed thermal micro-environment with quilts. The effect of the thermal resistance of quilts on the temperature field in the bed and dry heat loss of a human body was studied. Thermal manikin was used to resemble person in bed. Four quilts with different properties such as weight and non-uniform filling and type of filling material (Muscovy down and polyester fibre) were studied. Full-scale experiments were conducted in a ventilated climate chamber under four thermal conditions including two levels of relative humidity (50% and 70%) and two air temperatures (15ᵒC and 20ᵒC). The dry heat loss of the thermal manikin was higher with polyester fibre quilt than with quilt having the same weight but with Muscovy down filling. This was obtained under all tested room conditions. The studied non-uniformity in down distribution of the quilt provided similar thermal insulation on the feet and chest.

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Budnik, S. A., A. N. Nenarokomov, and D. M. Titov. "Investigation of Passive Systems for Thermal Control of Spacecraft." Journal of Engineering Physics and Thermophysics 91, no. 6 (November 2018): 1565–72. http://dx.doi.org/10.1007/s10891-018-1894-9.

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Kenisarin, Murat, and Khamid Mahkamov. "Passive thermal control in residential buildings using phase change materials." Renewable and Sustainable Energy Reviews 55 (March 2016): 371–98. http://dx.doi.org/10.1016/j.rser.2015.10.128.

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Cheng, Sun, Liu, Liu, Li, Li, and Hu. "Engineering Design of an Active–Passive Combined Thermal Control Technology for an Aerial Optoelectronic Platform." Sensors 19, no. 23 (November 28, 2019): 5241. http://dx.doi.org/10.3390/s19235241.

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: In order to ensure the imaging performance of the aerial optoelectronic platform system in low temperature environment, an active-passive combined thermal control technology was studied. A thermal control finite element model of the aerial optoelectronic platform was established. Additionally, thermal control simulation analysis and experiments under extreme conditions were carried out respectively. The simulation and experimental results showed that the temperature level of the primary mirror is improved above 25 ℃ by the proposed thermal control technology effectively, meanwhile the temperature gradient of the primary and secondary mirrors are less than 5 ℃. The successful implementation of this active-passive combined thermal control technology provides a technical support for the precision thermal control of aerial optoelectronic platforms.

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Fořt, Jan, Jan Kočí, Jaroslav Pokorný, Luboš Podolka, Michal Kraus, and Robert Černý. "Characterization of Responsive Plasters for Passive Moisture and Temperature Control." Applied Sciences 10, no. 24 (December 20, 2020): 9116. http://dx.doi.org/10.3390/app10249116.

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Ambient comfort maintenance accompanied by excessive energy consumption is hugely criticized concerning the limited sustainability of the building sector in the long-term. In this sense, the energy reduction strategies based on the employment of passive air-control techniques are viewed as a prospective solution for improved energy performance. In order to contribute to this significant issue, this paper is aimed at the design and material characterization of novel plaster with an improved thermal and humidity control performance. For this purpose, a form-stable diatomite/dodecanol-based phase change material together with superabsorbent polymer are used as admixtures for the passive moderation of indoor air quality by newly designed modified plasters. The experimental assessment of the functional properties by means of mechanical strength, thermal conductivity, and hygric properties is performed. Considering the goal of the paper, particular attention is paid to the characterization of water vapor storage and moisture buffering according to the Nordtest method. Differential scanning calorimetry is employed for the description of phase change intervals as well as the specific enthalpy of phase change. The obtained results point to significant improvements in the hygroscopic performance and increased thermal energy storage that can be used for passive moderation of the indoor temperature and reduction of the relative humidity swings.

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YOSHINO, Hiroshi, and Ken AOZASA. "MEASUREMENT ON THERMAL ENVIRONMENT OF THE ATRIUM WITH PASSIVE CONTROL SYSTEM." AIJ Journal of Technology and Design 2, no. 3 (1996): 207–10. http://dx.doi.org/10.3130/aijt.2.207.

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Dissertations / Theses on the topic "Passive thermal control"

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Zhou, Guo. "Predictive optimal control of active and passive building thermal storage inventory." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1453539.

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Morgan, Steve. "Experimental analysis of optimal control of passive and active building thermal storage inventory." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1442942.

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Cheng, Calvin Hwakong. "Impacts on the cost savings potential for using passive thermal storage for cooling control." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1435224.

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Li, Y. "Thermal performance analysis of a PCM combined solar chimney system for natural ventilation and heating/cooling." Thesis, Coventry University, 2013. http://curve.coventry.ac.uk/open/items/0bca9412-8b49-4d3c-84e5-453e315d4c6b/1.

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Solar chimney is an important passive design strategy to maximize solar gain to enhance buoyancy effect for achieving adequate air flow rate and a desired level of thermal comfort inside a building. Therefore, solar chimney has the potential advantages over mechanical ventilation systems in terms of energy requirement, economic and environmental benefits. The main aim of this project is to study the technical feasibility of a solar chimney incorporating latent heat storage (LHS) system for domestic heating and cooling applications. The research work carried out and reported in this thesis includes: the development of a detailed theoretical model to calculate the phase change material (PCM) mass for solar chimney under specific climatic condition, the development of a CFD model to optimise the channel depth and the inlet and outlet sizes for the solar chimney geometry, experimental and numerical investigations of the thermal performance of the proposed system using a prototype set-up, a parametric study on the proposed system to identify significant parameters that affect the system performance was carried out by using the verified numerical model. The numerical and experimental study showed that the numerical model has the ability to calculate the PCM mass for the proposed system for the given weather conditions. The optimum PCM should be selected on the basis of its melting temperature, rather than its other properties such as latent heat. The experimental work on the thermal performance of the proposed system has been carried out. The results indicated that the LHS based solar chimney is technically viable. The outlet air temperature and the air flow rate varied within a small range during phase change transition period which are important for a solar air heating system. A numerical model was developed to reproduce the experimental conditions in terms of closed mode and open mode. The model results were in a close agreement with the experimental results particularly the simulated results for the discharging process. With the verified model, a comprehensive parametric analysis intended to optimise the thermal performance of proposed the system was performed. The results analysed are quantified in terms of charging/discharging time of the PCM, temperature difference between outlet air and inlet air of the solar chimney, and mass flow rate of the chimney, which are the most important quantities of the proposed system.

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Tran, Nicolas. "Influence de la condition limite acoustique amont sur les instabilités de combustion de grande amplitude : conception d’un système robuste de contrôle d’impédance." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2009. http://www.theses.fr/2009ECAP0013/document.

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Les contraintes économiques, environnementales et sociétales de ces vingt dernières années notamment dans les domaines de l’énergie et des transports ont débouché sur le développement de nouvelles technologies faisant intervenir la combustion pauvre et prémélangée. Ce mode de combustion à partir d'un mélange homogène conduit à des températures de flamme plus faibles qui permettent de réduire les émissions d'oxydes d'azote tout en limitant la production d'oxydes de carbone. Pour autant, la combustion pauvre prémélangée présente le désavantage d’être sensible à toute forme de couplage notamment acoustique, menant à des instabilités de combustion. Ces instabilités sont largement étudiées, mais restent très difficiles à prévoir car elles font intervenir de nombreux phénomènes physiques multi-échelles. Dans la plupart des cas les oscillations résultent d’un couplage résonant entre la dynamique de la combustion et l’acoustique du système. Les conditions aux limites acoustiques du système déterminent la structure du champ de pression dans l’installation, ainsi que les flux acoustiques entrants et sortants. Malgré son importance, l’influence des conditions aux limites n’est pas toujours bien comprise et prise en compte et elle ne fait pas l’objet d’études systématiques. Les conditions aux limites acoustiques ne sont pas faciles à déterminer expérimentalement sur des configurations pratiques et leur contrôle est rarement envisagé. L’objectif de ce travail est donc de répondre à ce manque d’information, en étudiant sur un banc de combustion turbulente (CTRL-Z) l’influence de la condition acoustique d’entrée sur les oscillations de combustion auto-entretenues qui apparaissent dans la chambre de combustion. Un système de contrôle a été développé pour piloter l’impédance du système de prémélange de façon passive, sans modification des conditions de fonctionnement ou de la géométrie du brûleur. Ce système de contrôle d’impédance (ICS, « Impedance Control System ») s’appuie sur une utilisation de plaques perforées faiblement poreuses, au travers desquelles circule un écoulement. Un piston mobile permet de piloter la profondeur de la cavité résonante formée en amont des plaques, et ainsi de piloter leurs impédances. L’impédance de ces plaques perforées a été étudiée pour de faibles et de forts niveaux d’excitation acoustique, et un critère de transition entre les régimes linéaire et non-linéaire a été déterminé. L’ICS a été optimisé pour permettre un contrôle du module du coefficient de réflexion de 0 à 1 sur une large plage de fréquences (100 à 1000 Hz) et de niveaux d’amplitude de perturbations (100 à 150 dB) couvrant ainsi la gamme des instabilités thermoacoustiques classiques. L’ICS est utilisé pour contrôler l’impédance d’entrée du système de prémélange du banc CTRL-Z, en regard de la zone de combustion. L’analyse spectrale des fluctuations de pression et de dégagement de chaleur en fonction de l’impédance d’entrée démontre qu’il est possible d’obtenir un amortissement de l’instabilité principale pouvant atteindre 20 dB. Ces résultats sont confirmés par une estimation au premier ordre d’un bilan d’énergie acoustique prenant en compte le terme source dû à la combustion ainsi que les flux acoustiques en amont et aval de la zone de flamme. Ce bilan démontre par ailleurs l’importance du flux d’énergie transmis vers l’amont, du même ordre de grandeur que le terme source, et souligne la nécessité de prendre en compte ces flux pour déterminer correctement le taux de croissance de l’énergie. Finalement, une analyse acoustique de l'installation a été menée pour déterminer la nature des modes d'instabilités observés et pour examiner les conditions nécessaires au bon fonctionnement de l'ICS
Combustion instabilities induced by a resonant flame-acoustic coupling are commonly observed in most applications of combustion from gas turbines to domestic or industrial boilers. These oscillations are detrimental by nature, and are still very difficult to predict at the design stage of a combustor. They imply numerous physical phenomena at multiple scales. They mainly result from a resonant coupling between the unsteady combustion and the acoustics of the system. The basic driving and coupling mechanisms have been extensively studied: acoustics in complex geometries and combustion dynamics of turbulent swirled flames are now reasonably well understood. However the effects of the acoustic boundary conditions on the system stability are less well documented, as they are not easy to access or to control in practical systems. They are however of prime importance as they determine the acoustic fluxes at the inlets and outlets of the combustor, as well as the preferential eigenfrequencies of the system. The main objective of this study is to investigate experimentally the influence of the inlet boundary condition of a generic turbulent burner on the observed self-sustained thermoacoustic oscillations. To carry out this investigation, a passive control solution has been developed. An innovative use of perforated panels with bias flow backed by tunable cavities allows to control the acoustic impedance at the inlet of a lean swirled-stabilized staged combustor (CTRL-Z facility). This impedance control system (ICS) has been initially designed and tested in a high load impedance tube. This facility also allowed to develop a robust impedance measurement technique, along with experimental protocols to measure acoustic velocities and fluxes. The acoustic response of perforates in both linear and nonlinear regimes was investigated as function of the plate porosity, bias flow velocity, back-cavity depth and incident pressure wave amplitude and frequency. The transition between the linear regime and the detrimental nonlinear regime has been linked to the perforates geometrical and operational parameters. As a result the ICS enables control of its acoustic reflection coefficient from 1 to 0 in a wide frequency range, 100 to 1000 Hz, for low and large incident pressure amplitudes (from 100 to 150 dB). The ICS, once implemented on the CTRL-Z facility, allowed to passively control the inlet boundary condition of the combustion rig. The impedance measurement technique was successfully used in harsh combustion situations, with high noise levels, to obtain in-situ measurements of the ICS impedance. Spectral analysis of the pressure and heat-release rate fluctuations demonstrated damping of the main self-sustained oscillation by up to 20 dB. A quantitative estimation of the acoustic energy balance was then obtained, highlighting the importance of the inlet acoustic flux. In this configuration, this term is of the same order of magnitude as the driving Rayleigh source term. Finally, an acoustic analysis of the combustion rig was led to determine the nature of the observed combustion instabilities modes and examine conditions required for an effective use of the ICS

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Malik, Naveed ur Rehman. "Modelling, Analysis, and Control Aspects of a Rotating Power Electronic Brushless Doubly-Fed Induction Generator." Doctoral thesis, KTH, Elektrisk energiomvandling, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174349.

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This thesis deals with the modeling, analysis and control of a novel brushlessgenerator for wind power application. The generator is named as rotatingpower electronic brushless doubly-fed induction machine/generator (RPEBDFIM/G). A great advantage of the RPE-BDFIG is that the slip power recoveryis realized in a brushless manner. This is achieved by introducing an additionalmachine termed as exciter together with the rotating power electronicconverters, which are mounted on the shaft of a DFIG. It is shown that theexciter recovers the slip power in a mechanical manner, and delivers it backto the grid. As a result, slip rings and carbon brushes can be eliminated,increasing the robustness of the system, and reducing the maintenance costsand down-time of the turbine. To begin with, the dynamic model of the RPE-BDFIG is developed andanalyzed. Using the dynamic model, the working principle of the generatoris understood and its operation explained. The analysis is carried out atspeeds, ±20% around the synchronous speed of the generator. Moreover, thedynamics of the generator due to external load-torque disturbances are investigated.Additionally, the steady-state model is also derived and analyzed forthe machine, when operating in motor mode. As a next step, the closed-loop control of the generator is considered indetail. The power and speed control of the two machines of the generator andthe dc-link voltage control is designed using internal model control (IMC)principles. It is found that it is possible to maintain the stability of thegenerator against load-torque disturbances from the turbine and the exciter,at the same time maintain a constant dc-link voltage of the rotor converter.The closed-loop control is also implemented and the operation of the generatorwith the control theory is confirmed through experiments.In the third part of the thesis, the impact of grid faults on the behaviourof the generator is investigated. The operation of the generator and its responseis studied during symmetrical and unsymmetrical faults. An approachto successful ride through of the symmetrical faults is presented, using passiveresistive network (PRN). Moreover, in order to limit the electrical and mechanicaloscillations in the generator during unsymmetrical faults, the dualvector control (DVC) is implemented. It is found that DVC to a certain extentcan be used to safeguard the converter against large oscillations in rotorcurrents. Finally, for completeness of the thesis, a preliminary physical design ofthe rotating power electronic converter has been done in a finite elementsoftware called ANSYS. The thermal footprint and the cooling capability,with estimates of the heatsink and fan sizes, are presented. Besides, another variant of a rotating electronic induction machine whichis based on the Lindmark concept and operating in a single-fed mode is also investigated. It’s steady-state model is developed and verified through experiments.

QC 20151006

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Mateášik, Timko Marek. "Experimentální ověření pasivních prvků tepelné regulace družic." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443228.

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Diplomová práca sa zaoberá vplyvom termálnych medzivrstiev na tepelnú kontaktnú vodi- vosť a tepelný kontaktný odpor. Práca sa zameriava na aplikáciu termálnych medzivrstiev pre vylepšenie tepelnej kontaktnej vodivosti v tepelnom spínači a v kozmických zariade- niach obecne. Teoretická časť práce stručne skúma rôzne pasívne termálne kontrolné systémy použí- vane v kozmických zariadeniach, vrátane termálnych medzivrstiev, a vysvetľuje pozadie tejto práce. Táto práca ďalej skúma rôzne termálne medzivrstvy, predovšetkým povlaky a fólie, a uvádza výber vhodnej termálnej medzivrstvy. Experimentálna časť práce skúma povrchové parametre, tepelnú vodivosť a mikrotvr-dosť medených vzoriek, ktoré slúžia ako substrát pre povlak čistého striebra. Ďalej rieši podmienky merania, metódy vyhodnocovania a samotné experimentálne merania. Experimentálne merania sú vykonané v termo-vákuovej testovacej komore a na základe výsledkov sú vyvodené závery. Pre ďalšiu prácu sú uvedené doporučenia.

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Vidal, Fábio Duarte. "Modelling ventilation phenomena in passive houses." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/17314.

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Mestrado em Engenharia Civil
The present dissertation aims to combine the use of Computational Fluid Dynamics (CFD) software, to support the design of ventilation systems in passive houses. Sustainable construction is an increasing concern in the current construction market, finding in these houses a valid alternative in order to enhance energy savings in this sector. A passive house is known for achieving high levels of thermal comfort without consuming too much energy. In addition to an extremely rigorous thermal insulation, the use of highly efficient ventilation systems is one of the main factors in achieving such levels of comfort. Therefore, this dissertation intends to study the circulation of air associated to the mechanical ventilation system of a passive house in Portugal and consequent analysis of its thermal comfort. To achieve such purpose, a CFD commercial program called FLOW-3D® will be used. It was necessary to perform a validation of the program by comparing air velocities obtained numerically by the program and experimentally through the registration of air velocities in the studied passive house with the use of digital anemometers. Lastly, after the validation described above, an analysis over the thermal comfort of the building was performed, based on temperature registrations obtained experimentally and velocity values obtained from the numerical simulations.
A presente dissertação visa aliar o uso de programas de simulação numérica de fluidos, mais concretamente a mecânica dos fluidos computacional (CFD), no apoio à conceção de sistemas de ventilação em casas passivas. A construção sustentável é cada vez mais uma preocupação no mercado atual da construção, encontrando nessas casas uma alternativa muito válida no que toca a poupanças de energia neste setor. Uma casa passiva é reconhecida por obter altos níveis de conforto térmico sem necessidade de grandes consumos de energia. Para além de um isolamento térmico rigoroso, o uso de sistemas de ventilação de elevada eficiência é um dos principais fatores para atingir tais níveis de conforto. Esta dissertação pretende, por isso, fazer um estudo da circulação de ar resultante de um sistema de ventilação mecânica numa casa passiva construída em Portugal e a consequente análise do conforto térmico que nela se obtém, tendo sido utilizado um programa comercial de CFD, o FLOW-3D®. Foi necessário realizar uma validação do programa através da comparação de valores de velocidade do ar obtidos numericamente pelo respetivo algoritmo de cálculo e experimentalmente através do registo de velocidades do ar na casa passiva objeto de estudo, tendo-se utilizado para o efeito anemómetros digitais. Por fim, após a validação descrita anteriormente, foi feita uma análise do conforto térmico do edifício em estudo com base em registos de temperatura obtidos experimentalmente e de velocidades do ar obtidos da simulação efetuada.

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Farina, Jordan T. "Application of Multi-Port Mixing for Passive Suppression of Thermo-Acoustic Instabilities in Premixed Combustors." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/50533.

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The utilization of lean premixed combustors has become attractive to designers of industrial gas turbines as a means of meeting strict emissions standards without compromising efficiency. Mixing the fuel and air prior to combustion allows for lower temperature flame zones, creating the potential for drastically reduced nitrous oxide emissions. While effective, these systems are commonly plagued by combustion driven instabilities. These instabilities produce large pressure and heat release rate fluctuations due to a resonant interaction between the combustor acoustics and the flame. A primary feedback mechanism responsible for driving these systems is the propagation of Fuel/Air Ratio (FAR) fluctuations into the flame zone. These fluctuations are formed inside of the premixing chamber when fuel is injected into and mixed with an oscillating air flow.

The research presented here aimed to develop new technology for premixer designs, along with an application strategy, to avoid resonant thermo-acoustic events driven by FAR fluctuations. A passive fuel control technique was selected for investigation and implementation. The selected technique utilized fuel injections at multiple, strategically placed axial locations to target and inhibit FAR fluctuations at the dominant resonant mode of the combustor. The goal of this research was to provide an understanding of the mixing response inside a realistic premixer geometry and investigate the effectiveness of the proposed suppression technique.

The mixing response was investigated under non-reacting flow conditions using a unique modular premixer. The premixer incorporated variable axial fuel injection locations, as well as interchangeable mixing chamber geometries. Two different chamber designs were tested: a simple annular chamber and one incorporating an axial swirler. The mixing response of the simple annular geometry was well characterized, and it was found that multiple injections could be effectively configured to suppress the onset of an unstable event at very lean conditions. Energy dense flame zones produced at higher equivalence ratios, however, were found to be uncontrollable using this technique. Additionally, the mixing response of the swirl geometry was difficult to predict. This was found to be the result of large spatial gradients formed in the dynamic velocity field as acoustic waves passed through the swirl vanes.

Ph. D.

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Sadrizadeh, Sasan. "Design of Hospital Operating Room Ventilation using Computational Fluid Dynamics." Doctoral thesis, KTH, Strömnings- och klimatteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-181053.

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The history of surgery is nearly as old as the human race. Control of wound infection has always been an essential part of any surgical procedure, and is still an important challenge in hospital operating rooms today. For patients undergoing surgery there is always a risk that they will develop some kind of postoperative complication. It is widely accepted that airborne bacteria reaching a surgical site are mainly staphylococci released from the skin flora of the surgical staff in the operating room and that even a small fraction of those particles can initiate a severe infection at the surgical site. Wound infections not only impose a tremendous burden on healthcare resources but also pose a major threat to the patient. Hospital-acquired infection ranks amongst the leading causes of death within the surgical patient population. A broad knowledge and understanding of sources and transport mechanisms of infectious particles may provide valuable possibilities to control and minimize postoperative infections. This thesis contributes to finding solutions, through analysis of such mechanisms for a range of ventilation designs together with investigation of other factors that can influence spread of infection in hospitals, particularly in operating rooms. The aim of this work is to apply the techniques of computational fluid dynamics in order to provide better understanding of air distribution strategies that may contribute to infection control in operating room and ward environments of hospitals, so that levels of bacteria-carrying particles in the air can be reduced while thermal comfort and air quality are improved. A range of airflow ventilation principles including fully mixed, laminar and hybrid strategies were studied. Airflow, particle and tracer gas simulations were performed to examine contaminant removal and air change effectiveness. A number of further influential parameters on the performance of airflow ventilation systems in operating rooms were examined and relevant measures for improvement were identified. It was found that airflow patterns within operating room environments ranged from laminar to transitional to turbulent flows. Regardless of ventilation system used, a combination of all airflow regimes under transient conditions could exist within the operating room area. This showed that applying a general model to map airflow field and contaminant distribution may result in substantial error and should be avoided. It was also shown that the amount of bacteria generated in an operating room could be minimized by reducing the number of personnel present. Infection-prone surgeries should be performed with as few personnel as possible. The initial source strength (amount of colony forming units that a person emits per unit time) of staff members can also be substantially reduced, by using clothing systems with high protective capacity. Results indicated that horizontal laminar airflow could be a good alternative to the frequently used vertical system. The horizontal airflow system is less sensitive to thermal plumes, easy to install and maintain, relatively cost-efficient and does not require modification of existing lighting systems. Above all, horizontal laminar airflow ventilation does not hinder surgeons who need to bend over the surgical site to get a good view of the operative field. The addition of a mobile ultra-clean exponential laminar airflow screen was also investigated as a complement to the main ventilation system in the operating room. It was concluded that this system could reduce the count of airborne particles carrying microorganisms if proper work practices were maintained by the surgical staff. A close collaboration and mutual understanding between ventilation experts and surgical staff would be a key factor in reducing infection rates. In addition, effective and frequent evaluation of bacteria levels for both new and existing ventilation systems would also be important.
Tidigt i mänsklighetens utveckling har kirurgin funnits med i bilden. Hantering av infektioner har genom tiderna varit en oundviklig del av alla kirurgiska ingrepp, och finns kvar ännu idag som en viktig utmaning i operationssalar på sjukhus. För patienter som genomgår kirurgi finns alltid en risk att de efter ingreppet utvecklar någon behandlingsrelaterad komplikation. Allmänt accepterat är att de luftburna bakterier som når operationsområdet huvudsakligen består av stafylokocker frigjorda från hudfloran av operationspersonalen i operationssalen, och att endast en liten del av dessa partiklar behövs för att initiera en allvarlig infektion i det behandlade området. Sårinfektioner innebär inte bara en enorm börda för hälso- och sjukvårdsresurser, utan utgör också en betydande risk för patienten. På sjukhus förvärvad infektion finns bland de främsta dödsorsakerna i kirurgiska patientgrupper.. En bred kunskap och förståelse av spridningsmekanismer och källor till infektionsspridande partiklar kan ge värdefulla möjligheter att kontrollera och minimera postoperativa infektioner. Denna avhandling bidrar till lösningar genom analys av en rad olika ventilationssystem tillsammans med undersökning av andra faktörer som kan påverka infektionsspridningen på sjukhus, främst i operationssalar. Syftet med arbetet är att med hjälp av CFD-teknik (Computational Fluid Dynamics) få bättre förståelse för olika luftspridningsmekanismers betydelse vid ventilation av operationssalar och vårdinrättningar på sjukhus, så att halten av bacteriebärande partiklar i luften kan minskas samtidigt som termisk komfort och luftkvalité förbättras. Flera luftflödesprinciper för ventilation inklusive omblandade strömning, riktad (laminär) strömning och hybridstrategier har studerats. Simuleringar av luft-, partikel- och spårgasflöden gjordes för alla fallstudier för att undersöka partikelevakuering och luftomsättning i rummet. Flera viktiga parametrar som påverkar detta undersöktes och relevanta förbättringar föreslås i samarbete med industrin. Av resultaten framgår att mängden genererade bakterier i en operationssal kan begränsas genom att minska antalet personer i operationsteamet. Infektionsbenägna operationer skall utföras med så lite personal som möjligt. Den initiala källstyrkan (mängden kolonibildande enheter som en person avger per tidsenhet) från operationsteamet kan avsevärt minskas om högskyddande kläder används. Av resultaten framgår också att ett horisontellt (laminärt) luftflöde kan vara ett bra alternativ till det ofta använda vertikala luftflödet. Ett horisontellt luftflöde är mindre känsligt för termisk påverkan från omgivningen, enkelt att installera och underhålla, relativt kostnadseffektivt och kräver vanligen ingen förändring av befintlig belysningsarmatur. Framför allt begränsar inte denna ventilationsprincip kirurgernas rörelsemönster. De kan luta kroppen över operationsområdet utan att hindra luftflödet. En flyttbar flexibel skärm för horisontell spridning av ultraren ventilationsluft i tillägg till ordinarie ventilation undersöktes också. Man fann att denna typ av tilläggsventilation kan minska antalet luftburna partiklar som bär mikroorganismer om operationspersonalen följer en strikt arbetsordning. Bra samarbete och förståelse mellan ventilationsexperter och operationsteamet på sjukhuset är nyckeln till att få ner infektionsfrekvensen. Det är också viktigt med effektiva och frekventa utvarderingar av bakteriehalten i luften, för såväl nya som befintliga ventilationssystem.

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Books on the topic "Passive thermal control"

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Bansal, N. K. Passive building design: A handbook of natural climatic control. Amsterdam: Elsevier Science B.V., 1994.

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Book chapters on the topic "Passive thermal control"

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Long, E. L., and J. P. Zarling. "Passive Techniques for Ground Temperature Control." In Thermal Analysis, Construction, and Monitoring Methods for Frozen Ground, 77–165. Reston, VA: American Society of Civil Engineers, 2004. http://dx.doi.org/10.1061/9780784407202.ch04.

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Hilton, Harry H. "Aeroviscoelasticity Designer FGMs: Passive Control Through Tailored Functionally Graded Materials." In Encyclopedia of Thermal Stresses, 78–87. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-007-2739-7_550.

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Pal, D., and Y. K. Joshi. "Application of Phase Change Materials (PCMs) to the Passive Thermal Control of a Plastic Quad Flat Package: Effect of Orientation of the Package." In Thermal Management of Electronic Systems II, 227–42. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5506-9_22.

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Hay, Harold R. "100% NATURAL THERMAL CONTROL – PLUS." In Passive and Low Energy Ecotechniques, 532–45. Elsevier, 1985. http://dx.doi.org/10.1016/b978-0-08-031644-4.50034-5.

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"Passive Thermal Control of Electronic Equipment." In Applied Computational Fluid Dynamics, 317–50. CRC Press, 1998. http://dx.doi.org/10.1201/9781482270006-8.

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"5 Thermal design: passive controls." In Introduction to Architectural Science, 61–83. Routledge, 2008. http://dx.doi.org/10.4324/9780080878942-11.

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C. Ngwuluka, Ndidi, Nedal Y. Abu-Thabit, Onyinye J. Uwaezuoke, Joan O. Erebor, Margaret O. Ilomuanya, Riham R. Mohamed, Soliman M. A. Soliman, Mahmoud H. Abu Elella, and Noura A. A. Ebrahim. "Natural Polymers in Micro- and Nanoencapsulation for Therapeutic and Diagnostic Applications: Part I: Lipids and Fabrication Techniques." In Nano- and Microencapsulation - Techniques and Applications [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94856.

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Encapsulation, specifically microencapsulation is an old technology with increasing applications in pharmaceutical, agrochemical, environmental, food, and cosmetic spaces. In the past two decades, the advancements in the field of nanotechnology opened the door for applying the encapsulation technology at the nanoscale level. Nanoencapsulation is highly utilized in designing effective drug delivery systems (DDSs) due to the fact that delivery of the encapsulated therapeutic/diagnostic agents to various sites in the human body depends on the size of the nanoparticles. Compared to microencapsulation, nanoencapsulation has superior performance which can improve bioavailability, increase drug solubility, delay or control drug release and enhance active/passive targeting of bioactive agents to the sites of action. Encapsulation, either micro- or nanoencapsulation is employed for the conventional pharmaceuticals, biopharmaceuticals, biologics, or bioactive drugs from natural sources as well as for diagnostics such as biomarkers. The outcome of any encapsulation process depends on the technique employed and the encapsulating material. This chapter discusses in details (1) various physical, mechanical, thermal, chemical, and physicochemical encapsulation techniques, (2) types and classifications of natural polymers (polysaccharides, proteins, and lipids) as safer, biocompatible and biodegradable encapsulating materials, and (3) the recent advances in using lipids for therapeutic and diagnostic applications. Polysaccharides and proteins are covered in the second part of this chapter.

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C. Ngwuluka, Ndidi, Nedal Y. Abu-Thabit, Onyinye J. Uwaezuoke, Joan O. Erebor, Margaret O. Ilomuanya, Riham R. Mohamed, Soliman M.A. Soliman, Mahmoud H. Abu Elella, and Noura A.A. Ebrahim. "Natural Polymers in Micro- and Nanoencapsulation for Therapeutic and Diagnostic Applications: Part I: Lipids and Fabrication Techniques." In Nano- and Microencapsulation - Techniques and Applications. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.94856.

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Abstract:

Encapsulation, specifically microencapsulation is an old technology with increasing applications in pharmaceutical, agrochemical, environmental, food, and cosmetic spaces. In the past two decades, the advancements in the field of nanotechnology opened the door for applying the encapsulation technology at the nanoscale level. Nanoencapsulation is highly utilized in designing effective drug delivery systems (DDSs) due to the fact that delivery of the encapsulated therapeutic/diagnostic agents to various sites in the human body depends on the size of the nanoparticles. Compared to microencapsulation, nanoencapsulation has superior performance which can improve bioavailability, increase drug solubility, delay or control drug release and enhance active/passive targeting of bioactive agents to the sites of action. Encapsulation, either micro- or nanoencapsulation is employed for the conventional pharmaceuticals, biopharmaceuticals, biologics, or bioactive drugs from natural sources as well as for diagnostics such as biomarkers. The outcome of any encapsulation process depends on the technique employed and the encapsulating material. This chapter discusses in details (1) various physical, mechanical, thermal, chemical, and physicochemical encapsulation techniques, (2) types and classifications of natural polymers (polysaccharides, proteins, and lipids) as safer, biocompatible and biodegradable encapsulating materials, and (3) the recent advances in using lipids for therapeutic and diagnostic applications. Polysaccharides and proteins are covered in the second part of this chapter.

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BOND, GERARD C., MICHELLE A. KOMINZ, MICHAEL S. STECKLER, and JOHN P. GROTZINGER. "ROLE OF THERMAL SUBSIDENCE, FLEXURE, AND EUSTASY IN THE EVOLUTION OF EARLY PALEOZOIC PASSIVE-MARGIN CARBONATE PLATFORMS." In Controls on Carbonate Platforms and Basin Development, 39–61. SEPM (Society for Sedimentary Geology), 1989. http://dx.doi.org/10.2110/pec.89.44.0039.

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Conference papers on the topic "Passive thermal control"

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Citron, Robert, Thomas C. Taylor, Dr E. Vallerani, and Lazzaro Costamagna. "The SPACEHAB Module Passive Thermal Control." In Intersociety Conference on Environmental Systems. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1987. http://dx.doi.org/10.4271/871508.

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Pergande, Albert, and Janice C. Rock. "Advances in passive PCB thermal control." In 2011 IEEE Aerospace Conference. IEEE, 2011. http://dx.doi.org/10.1109/aero.2011.5747312.

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Perrygo, Charles M., Michael Choi, Keith A. Parrish, R. Greg Schunk, Diane Stanley, and Eve M. Wooldridge. "Passive thermal control of the NGST." In Astronomical Telescopes & Instrumentation, edited by Pierre Y. Bely and James B. Breckinridge. SPIE, 1998. http://dx.doi.org/10.1117/12.324510.

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Whalley, A. M. "Improvements in Passive Thermal Control for Spacecraft." In Intersociety Conference on Environmental Systems. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1988. http://dx.doi.org/10.4271/881022.

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Young, Eliot F., Bret P. Lamprecht, Ginger A. Drake, Kelly D. Smith, Robert A. Woodruff, and David A. Crotser. "Passive thermal control of balloon-borne telescopes." In 2015 IEEE Aerospace Conference. IEEE, 2015. http://dx.doi.org/10.1109/aero.2015.7119011.

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Young, Jennifer, Scott Inlow, and Brett Bender. "Solving Thermal Control Challenges for CubeSats: Optimizing Passive Thermal Design." In 2019 IEEE Aerospace Conference. IEEE, 2019. http://dx.doi.org/10.1109/aero.2019.8741754.

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Schor, Matthew J. "Passive thermal control with passive sun shield for low temperature sensors." In Aerospace Sensing, edited by Brian J. Horais. SPIE, 1992. http://dx.doi.org/10.1117/12.138028.

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WARREN, A., F. EDELSTEIN, L. ROYCE, and W. TIMLEN. "Passive thermal control for IR sensor in space." In 26th Thermophysics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1991. http://dx.doi.org/10.2514/6.1991-1424.

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Tyliszczak, Artur, Agnieszka Wawrzak, and Jakub Stempka. "APPLICATION OF ACTIVE AND PASSIVE CONTROL METHODS FOR DIFFUSION JET FLAMES." In 4th Thermal and Fluids Engineering Conference. Connecticut: Begellhouse, 2019. http://dx.doi.org/10.1615/tfec2019.cbf.027461.

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Phoenix, Austin A., and Evan Wilson. "Variable Thermal Conductance Metamaterials for Passive or Active Thermal Management." In ASME 2017 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/smasis2017-3767.

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To continue to meet spacecraft systems ever increasing thermal management requirements, new control methods need to be developed. While advances in metamaterials have provided the ability to generate materials with a broad range of material properties, relatively little advancement has been made in the development of adaptive metamaterials. This paper is focused on the development of a thermal management metamaterial that enables the active and passive control of a metamaterial’s thermal conductance. This variable conductivity is achieved through the application of internally or externally applied loads that induce internal contact resulting in changes in the conductive path length and the effective conductive area. This capability enables active or passive control of a metamaterial’s effective thermal conduction through the application of mechanical and thermal strain. Passively applied thermal strains can be used to design a highly nonlinear material thermal conductivity as a function of temperature. Actively, this can be used to precisely control the temperature of an interface through dynamically changing the instantaneous heat flux through the metamaterial. This work expands on the field of thermal switches by enabling a non-binary configuration where the initial air gap is slowly closed as contact sequentially introduced into the metamaterial. As internally or externally developed loading is applied, contact is introduced with an increasing contact area until full contact is achieved. This intermediate step of partial contact enables unique design capabilities that enable highly nonlinear thermal conductivity as a function of temperature as well as stability regions that allow passive thermal control. An example metamaterial was developed and evaluated to quantify the potential of this concept. The specific metamaterial configuration assessed in this paper uses offset flat and curved copper plates that are connected at the edges of the plate using a low conductivity epoxy. To evaluate the metamaterial performance, the stiffness and thermal conductivity are calculated as a function of the resulting contact area and the required applied loading. This work is focused on determining the potential of this metamaterial concept by evaluating this initial concept confirmation to establish the magnitude of the thermal conductance change, and the design of the conductivity change a function of applied loading.

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Reports on the topic "Passive thermal control"

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Gregor P. Henze and Moncef Krarti. Predictive Optimal Control of Active and Passive Building Thermal Storage Inventory. Office of Scientific and Technical Information (OSTI), September 2005. http://dx.doi.org/10.2172/894509.

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Gregor P. Henze and Moncef Krarti. Predictive Optimal Control of Active and Passive Building Thermal Storage Inventory. Office of Scientific and Technical Information (OSTI), December 2003. http://dx.doi.org/10.2172/894510.

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Gregor P. Henze and Moncef Krarti. Predictive Optimal Control of Active and Passive Building Thermal Storage Inventory. Office of Scientific and Technical Information (OSTI), January 2003. http://dx.doi.org/10.2172/894511.

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