Les systèmes de stockage thermochimique s’avèrent être de bonnes alternatives aux technologies actuelles pour le stockage saisonnier ou intersaisonnier de la chaleur, car l’énergie est stockée sous forme d’un potentiel chimique et donc, il n’y a pas de pertes thermiques pendant la durée de stockage. Un grand nombre d’études a été mené sur le développement de réacteurs thermochimiques intégrés au système de stockage, et peu d’étude ont été menées sur les technologies de réacteur séparé du réservoir de stockage. Ces dernières présentent cependant l’avantage, entre autres, de dissocier la puissance thermique du réacteur et la capacité de stockage de l’installation, ce qui permettrait d’augmenter la densité de stockage.Cette étude se penche sur le développement d’un réacteur thermochimique à lit mobile fonctionnant avec des sels hydratés sous air humide, adapté à des applications aux réseaux de chaleur. Un prototype de réacteur, développé et construit durant cette étude, a permis d’analyser le fonctionnement du réacteur. Cette étude a, entre autres, mis en évidence l’impact des passages préférentiels de l’air sur les performances du réacteur (température et puissance), ainsi que l’importance du titre de vapeur de l’air à l’entrée du réacteur sur ces performances. Il apparaît également que la circulation du solide abaisse sensiblement le point d’équilibre atteint par la réaction.De plus, deux modèles mathématiques ont été développés : un modèle analytique 1D et un modèle 2D prenant en compte les phénomènes de transfert de matière et de chaleur au sein de la zone réactive. Le modèle 2D, validé avec les résultats expérimentaux, a été exploité à l’aide du logiciel de simulation par éléments finis COMSOL Multiphysics afin de mener une étude théorique sur le fonctionnement et les performances du réacteur. Cette étude numérique a porté sur l’influence des conditions opératoires (débit et taux d’humidité de l’air, vitesse du solide) sur les performances et le rendement du système et a permis la comparaison des réacteurs à lit mobile par rapport aux réacteurs à lit fixes, communément développés pour des applications de stockage thermochimique. Cette étude a montré l’importance de la régulation de la vitesse du solide pour l’optimisation des performances du réacteur à lit mobile.L’ensemble de cette étude a permis de mettre en évidence les avantages et les limitations d’un réacteur à lit mobile pour des applications de stockage thermochimique / Thermochemical storage systems prove to be good alternatives to current technologies for seasonal or inter-seasonal storage of heat, because energy is stored as a chemical potential and therefore, there is no heat loss during the storage period. Nowadays, a large number of studies have been conducted on the development of thermochemical reactor integrated in the storage system, andlittle study has been conducted on reactor technologies separated from the storage system. The latter, however, have the advantage, among others, of separating the thermal power produced or consumed and the storage capacity of the installation, which would increase the storage density.This study investigates the development of a moving-bed thermochemical reactor operating with hydrated salts and humid air cross-flow, suitable for district heating applications. A reactor prototype, developed and built during this study, allowed to analyze the functioning of the reactor. This study has, among others, highlighted the impact of the preferential air flow path on the reactorperformances (temperature and power), as well as the importance of the air humidity at the reactor inlet on these performances.In addition, two mathematical models have been developed : a 1D analytical model and a 2D model taking into account the heat and mass transfer phenomena within the reactive area. The 2D model, validated with the experimental results, was exploited using the finite element simulation software COMSOL Multiphysics to conduct a theoretical study on the functioning and the performances of the reactor. This numerical study focused on the influence of operating conditions (air flow rate and moisture content, solid flow rate) on the performances and the efficiency of the system and allowed the comparison of moving bed reactor over fixed bed reactors, commonly developed for thermochemical storage applications. This study has shown the importance of solid velocity control for optimizing the performances of the moving bed reactor.This study has highlighted the advantages and limitations of moving bed reactors for thermochemical storage applications

O objetivo do estudo foi a avaliação dos mecanismos termorreguladores, baseada numa abordagem temporal em função de diferentes armazenamentos de calor, proporcionados por diferentes tipos de ambientes térmicos (com e sem radiação solar). Foram utilizadas 12 búfalas da raça Mediterrânea que foram submetidas a quatro experimentos durante o verão de 2010 a 2012 delineados para o comprimento dos objetivos específicos. Nos vários experimentos os parâmetros meteorológicos registrados foram: temperatura de bulbo seco, temperatura de bulbo úmido, umidade relativa do ar, velocidade do vento e temperatura de globo negro. Os parâmetros fisiológicos avaliados foram: temperatura retal, temperatura da base da cauda, temperatura da epiderme, temperatura de superfície do pelame, frequência respiratória e taxa de sudação. As análises estatísticas foram realizadas com auxílio do programa Statistical Analysis System, versão 9.1.3 (SAS Institute Inc., Cary, NC, USA), utilizando-se os procedimentos PROC MIXED. No experimento 1 que visou verificar as reações termorreguladoras ao ambiente aquecido em unidade biometeorológica, o aumento da temperatura do ar em ambiente controlado influenciou todas as variáveis fisiológicas ao longo do dia (P<0,01). O incremento na taxa de sudação durante o período de estresse térmico determinou a depleção na concentração plasmática de potássio (P=0,0051). No experimento 2que avaliou as reações termorreguladoras na presença de radiação solar direta averiguamos que houve influência da exposição ao sol sobre todas as variáveis fisiológicas ao longo do dia (P<0,01). O gradiente térmico favorável no período noturno atenuou os efeitos do estresse térmico não constatando o efeito da exposição a radiação solar direta sobre os constituintes sanguíneos. No experimento 3que objetivou quantificar a velocidade de aquisição de calor ao sol comparando-a posteriormente com a velocidade de dissipação do calor à sombra, constatamos que a exposição por uma hora ao sol incrementou a frequência respiratória em 189,24 % e a temperatura retal em 1,46 %, após o retorno a sombra, por uma hora, verificamos uma redução de 191,75 % e 0,57 %, respectivamente. No experimento 4avaliamos a dinâmica da termólise evaporativa e o balanço térmico de radiação e convecção em condições de radiação solar direta. À medida que reduz a temperatura radiante média, os animais passam a perder o calor armazenado por radiação, reduzem as perdas por polipnéia térmica ao passo que as perdas por sudação permanecem altas. / The aim of the study was to evaluate the thermoregulatory mechanisms, based on a temporal approach, in relation to different heat storages provided by different types of thermal environments (with and without solar radiation). Twelve Mediterranean buffalo heifers were submitted to four experiments during the summer of 2010 to 2012 outlined to achieve specific objectives. Environmental parameters dry bulb temperature; wet bulb temperature; relative humidity; winds speed and black globe temperature were measured. Physiological parameters rectal temperature; base of tail temperature; skin temperature; hair coat surface temperature; respiratory rate and sweating rate were measured. The statistical analysis were done with the assistance of the Statistical Analysis System, version9.1.3(SAS Institute Inc., Cary, NC, USA), using procedures UNIVARIATE,CORR, GLM and MIXED. The first experiment aimed to verify the thermoregulatory reactions of the warm environment in the climatic chamber. Increasing the air temperature in a controlled environment influenced all physiological variables throughout the day (P<0,01). The increase in the sweating rate during heat stress led to the depletion of plasma potassium (P=0,0051). In experiment 2, which assessed the thermoregulatory reactions in the presence of direct solar radiation, it was observed the influence of sun exposure on all physiological variables throughout the day (P<0.01). The favorable thermal gradient at night attenuated the effects of heat stress without identifying the effect of direct sun exposure on blood constituents. In experiment 3, that aimed to measure the heat acquisition rate under the sun subsequently comparing it with the speed of heat dissipation under the shade, it was observed that one hour exposure to the sun increased respiratory rate at 189,24 % and rectal temperature at 1,46 %. After returning the shade for one hour, it was found reductions of 191,75 % and 0,57 %, respectively. The Experiment 4 evaluated the dynamics of evaporative thermolysis and thermal balance of radiation and convection under conditions of direct solar radiation. Reducing the mean radiant temperature, the animals started to lose the stored heat by radiation, reduced losses by thermal polipneia while the losses by sweating remain high.

Cette recherche est basée sur une étude numérique de performances thermiques d'un habitat bioclimatique. Dans cette étude, nous avons considérés deux habitats bioclimatiques, l'un concernant un habitat classique de toiture en tôles d'aluminium, de faux plafond en laine de bois et le second, un habitat intégrant du panneau de MCP qui sépare la toiture en tuiles transparentes de l'enceinte parallélépipédique. Les équations de transfert de chaleur dans l'habitat sont basées sur la méthode nodale et sont déduites d'un bilan thermique établi pour les différents composants de l'habitat. Les transferts de chaleur dans l'unité de stockage sont axées sur la méthode enthalpique et purement conductif. Elles sont résolues par une méthode implicite aux différences finies et les algorithmes de Gauss et de Thomas. Nous avons analysé l'influence de certains paramètres tels que : le flux solaire, l'épaisseur du mur, la température maximale et minimale, et le taux de renouvellement d'air sur les distributions de températures des composants de l'habitat et de l'unité de stockage, les efficacités thermiques de stockage et de déstockage de l'unité de stockage. Une modélisation des phénomènes de transfert de chaleur dans l'habitat et dans l'unité de stockage est présentée, complétée par une simulation du fonctionnement du système basée sur les notions de journée type à travers les données météorologiques de la région de Ouagadougou et terminé par une analyse technico-économique. / This research is based on a numerical study of thermal performances of a bioclimatic habitat. In this study, we considered two bioclimatic habitats, one concerning a conventional aluminum roofing habitat, wood-wool false ceilings, and the second, a habitat incorporating a MCP panel that separates the roof into tiles transparent parallelepipedic enclosure. The heat transfer equations in the habitat are based on the nodal method and are deduced from a heat balance established for the different components of the habitat. The heat transfers in the storage unit are focused on the enthalpy and purely conductive method. They are solved by an implicit finite difference method and the Gauss and Thomas algorithms. We analyzed the influence of certain parameters such as: solar flux, wall thickness, maximum and minimum temperature, and the rate of air exchange on the temperature distributions of the components of the habitat and water. Storage unit, the thermal efficiencies of storage and retrieval of the storage unit. A modeling of the heat transfer phenomena in the habitat and in the storage unit is presented, completed by a simulation of the functioning of the system based on the notions of typical day through the meteorological data of the region of Ouagadougou and ended by a technical and economic analysis.

O objetivo do estudo foi a avaliação dos mecanismos termorreguladores, baseada numa abordagem temporal em função de diferentes armazenamentos de calor, proporcionados por diferentes tipos de ambientes térmicos (com e sem radiação solar). Foram utilizadas 12 búfalas da raça Mediterrânea que foram submetidas a quatro experimentos durante o verão de 2010 a 2012 delineados para o comprimento dos objetivos específicos. Nos vários experimentos os parâmetros meteorológicos registrados foram: temperatura de bulbo seco, temperatura de bulbo úmido, umidade relativa do ar, velocidade do vento e temperatura de globo negro. Os parâmetros fisiológicos avaliados foram: temperatura retal, temperatura da base da cauda, temperatura da epiderme, temperatura de superfície do pelame, frequência respiratória e taxa de sudação. As análises estatísticas foram realizadas com auxílio do programa Statistical Analysis System, versão 9.1.3 (SAS Institute Inc., Cary, NC, USA), utilizando-se os procedimentos PROC MIXED. No experimento 1 que visou verificar as reações termorreguladoras ao ambiente aquecido em unidade biometeorológica, o aumento da temperatura do ar em ambiente controlado influenciou todas as variáveis fisiológicas ao longo do dia (P<0,01). O incremento na taxa de sudação durante o período de estresse térmico determinou a depleção na concentração plasmática de potássio (P=0,0051). No experimento 2que avaliou as reações termorreguladoras na presença de radiação solar direta averiguamos que houve influência da exposição ao sol sobre todas as variáveis fisiológicas ao longo do dia (P<0,01). O gradiente térmico favorável no período noturno atenuou os efeitos do estresse térmico não constatando o efeito da exposição a radiação solar direta sobre os constituintes sanguíneos. No experimento 3que objetivou quantificar a velocidade de aquisição de calor ao sol comparando-a posteriormente com a velocidade de dissipação do calor à sombra, constatamos que a exposição por uma hora ao sol incrementou a frequência respiratória em 189,24 % e a temperatura retal em 1,46 %, após o retorno a sombra, por uma hora, verificamos uma redução de 191,75 % e 0,57 %, respectivamente. No experimento 4avaliamos a dinâmica da termólise evaporativa e o balanço térmico de radiação e convecção em condições de radiação solar direta. À medida que reduz a temperatura radiante média, os animais passam a perder o calor armazenado por radiação, reduzem as perdas por polipnéia térmica ao passo que as perdas por sudação permanecem altas. / The aim of the study was to evaluate the thermoregulatory mechanisms, based on a temporal approach, in relation to different heat storages provided by different types of thermal environments (with and without solar radiation). Twelve Mediterranean buffalo heifers were submitted to four experiments during the summer of 2010 to 2012 outlined to achieve specific objectives. Environmental parameters dry bulb temperature; wet bulb temperature; relative humidity; winds speed and black globe temperature were measured. Physiological parameters rectal temperature; base of tail temperature; skin temperature; hair coat surface temperature; respiratory rate and sweating rate were measured. The statistical analysis were done with the assistance of the Statistical Analysis System, version9.1.3(SAS Institute Inc., Cary, NC, USA), using procedures UNIVARIATE,CORR, GLM and MIXED. The first experiment aimed to verify the thermoregulatory reactions of the warm environment in the climatic chamber. Increasing the air temperature in a controlled environment influenced all physiological variables throughout the day (P<0,01). The increase in the sweating rate during heat stress led to the depletion of plasma potassium (P=0,0051). In experiment 2, which assessed the thermoregulatory reactions in the presence of direct solar radiation, it was observed the influence of sun exposure on all physiological variables throughout the day (P<0.01). The favorable thermal gradient at night attenuated the effects of heat stress without identifying the effect of direct sun exposure on blood constituents. In experiment 3, that aimed to measure the heat acquisition rate under the sun subsequently comparing it with the speed of heat dissipation under the shade, it was observed that one hour exposure to the sun increased respiratory rate at 189,24 % and rectal temperature at 1,46 %. After returning the shade for one hour, it was found reductions of 191,75 % and 0,57 %, respectively. The Experiment 4 evaluated the dynamics of evaporative thermolysis and thermal balance of radiation and convection under conditions of direct solar radiation. Reducing the mean radiant temperature, the animals started to lose the stored heat by radiation, reduced losses by thermal polipneia while the losses by sweating remain high.

Heat stress is a well documented hazard across industries. The combination of environmental conditions, work demands, and clothing contribute to heat strain. Left unchecked, heat strain causes changes in an individual's physiological state that can lead to serious and fatal conditions with little warning. Although engineering and administrative controls are the first choice to abate this hazard, they frequently are not feasible. In these cases, personal cooling is often employed. There are three main types of personal cooling: liquid, air, and passive. Each has its own advantages and disadvantages. This study focuses on continuous cooling using a portable liquid cooling system (LCS). The LCS used a vest with tubes circulating water from an ice heat sink. The experiment consisted of five males each completing seven tests in random order. The subjects wore work clothes as the control then in conjunction with a firefighter, vapor barrier, and bomb suits. Each suit was tested with and without the benefit of the LCS. All of the tests took place at 35oC dry bulb and 50% relative humidity while attempting to walk 90 minutes on a treadmill at a 300 W metabolic rate. The study found continuous use of the LCS significantly reduced heat storage (S) and the rate of rise of heart rate (rrHR), core temperature (rrTre), and mean skin temperature (rrTsk) for the firefighter and vapor barrier suits as compared to no-cooling. Although the LCS didn't significantly affect the rate of rise for physiological responses with the bomb suit, it did however, significantly increase the endurance time. Interestingly, the study also found when wearing either the vapor barrier or firefighter suits in conjunction with the LCS that the rrHR and rrTre were not significantly different from only wearing work clothes.

This thesis seeks to examine the effective convective heat exchange of sand as a heat exchange medium. The goal of this exploratory research is to quantify the heat transfer coefficient of sand in a proposed Thermal Energy Storage (TES) system which intends to complement solar thermal power generation. Standard concentrator solar thermal power plants typically employ a heat transfer fluid (HTF) that is heated in the collector field then routed to the power generators or TES unit. A fairly clear option for a TES system would be to utilize the existing HTF as the working storage medium. However, the use of conventional HTF systems may be too expensive. These fluids are quite costly as the quantity needed for storage is high and for some fluids their associated high vapor pressures require expensive highly reinforced containment vessels. The proposed storage system seeks to use sand as the storage medium; greatly reducing the expenses involved for both medium and storage costs. Most prior TES designs using sand or other solids employed them in a fixed bed for thermal exchange. The proposed TES system will instead move the sand to drive a counter flow thermal exchange. This counter flow design allows for a much closer temperature of approach when compared to a fixed bed. As cost and performance are the primary goals to tackle of the proposed system, the evaluation of the sandâ s thermal exchange effectiveness in a flowing state is necessary. Experiments will be conducted to measure the effective heat transfer coefficient between the sand and representative solid surfaces used as the heat transfer conduits. Additional experiments that will be looked at are wear caused by the sand as a consideration for long term design viability as well as angle of repose of the sand and its effect on scoop design for improved materials handling. Key investigational aspects of these experiments involve the sand grain size as well as shape of the heat exchanger surfaces. The thesis will evaluate the resulting convective heat transfer coefficient of the sand as related to these features. The data will then be compared and verified with available literature of previously studied characteristic thermal properties of sand. The measured and confirmed data will then be used to further aid in a design model for the proposed TES system.

Heat stress is a common physical agent associated with many occupations. The most commonly used method of assessing heat stress exposure is an empirical method using the Wet Bulb Globe Temperature Index but his method is limited in its ability to parse out individual contributors to the heat stress. The International Organization for Standardization (ISO) published a rational model called Predicted Heat Strain (PHS) in 2004, and rational methods have the advantage of separating out the individual pathways for heat exchange. The objective of this research was a performance assessment of the current PHS model. This experimental design consisted of 15 trials (3 clothing ensembles and 5 heat stress levels) involving 12 men and women. The clothing ensembles were work clothes, NexGen® (microporous) coveralls, and Tychem® QC (vaporbarrier) coveralls. The heat stress levels were 1.0 , 2.0 , 3.5 , 5.5 and 9.0 °CWBGT above the average critical environment for each ensemble determined in prior studies. The metabolic rate was 190 W/m2. The two outcomes of each trial were an exposure time when core temperature reached 38 °C (ET38) and a Safe Exposure Time (SET) defined as the amount of time required to reach either a core temperature (Tre) = 38.5 ºC, a heart rate of 85% age-estimated maximum, or fatigue. ix Trial data for environment, metabolic rate and clothing were inputs to the (PHS) model to determine a predicted amount of time for the participants to reach a Tre = 38 ºC, which was the limiting condition in PHS for acute exposures. The first consideration was predictive validity for which PHS-Time was compared to ET38. The expectation would be that PHS-Time would predict the mean ET response. Results for predictive validity indicated a moderate agreement between ET38 and PHS-Time (r2 of 0.34 and Intraclass Correlation Coefficient at 0.33). When the method for accounting for clothing was changed to that recommended by ISO, the PHS predicted times moved systematically toward a shorter exposure time and modest agreement (r2 of 0.39 and Intraclass Correlation Coefficient at 0.31). Protective validity was the ability of the PHSTime to predict an exposure time that would be safe for most people. In this case, PHS-Time was compared to SET. The PHS was protective for 73% of the cases. When it was modified to account for clothing following the ISO method, the protective outcomes were 98%. In addition, the PHS model examined with respect to starting core temperature and fixed height and weight. Using the actual core temperature improved the outcomes somewhat, but changing from 36.8 to 37.0 would be sufficient. There is a strong tendency to over-predict PHS-Time for individuals with a low body surface area, usually short and lower than average weight.

The study is experimentally inclined, with a high target precision for performance measurement. A comprehensive programme of measurements was carried out in a two-storey building, having a massive structure and dating from 1970. Measurements were made continuously during the heating season from a total of about 70 points. Readings were taken every 30 seconds, and the mean values stored in a computer every 15 minutes. Analysis of the results have been concentrated on: * Thermal inertia, and particularly that of cooling mechanisms. * Time delays in heat flows through the building envelope in response to variations in ambient temperature. * The amount of solar input beneficially retained when operating with night setback and with normal operation. The results indicate that the building has both a long time constant, of about 200 h, and a short one, of about 1.5 h. The magnitude of the shorter time constant depends on the thermal capacity of the interior of the building (furniture, curtains etc.), and can be regarded as having some validity for other apartment building stock. Analyses of temperature gradients in the internal surfaces of the exterior walls indicate that the building's ventilation system, which was originally constructed as an exhaust air ventilation system, but with the inflow of fresh air blocked off, generates a dynamic insulation effect. Calculations indicate that this effect can provide a saving of 6 % of the total heating requirement, excluding that for domestic hot water. Investigation of the static heat requirement with and without night set-back indicate a considerable potential annual saving of heating energy, amounting to a maximum of 13 %, provided that the building is heated in accordance with a prescribed strategy. A 'comfort indoor temperature' has also been determined, being the temperature above which the occupants of the building consume excessive heating energy. Theoretical models have been derived to illustrate the short time constant and to analyse the dynamic insulation effect noted. / <p>Diss. Umeå : Umeå universitet, 1987</p> / digitalisering@umu

ABSTRACT HEAT REMOVAL FROM A LARGE SCALE WARM WATER STORAGE Kayserilioglu, Yavuz Selim M.S., Department of Mechanical Engineering Supervisor: Prof. Dr. R&uuml / knettin Oskay August 2004, 88 Pages A preliminary experimental study was performed in order to investigate the charging and heat removal characteristics of a sensible heat storage. Two sets of experiments were performed at two aspect ratios. Heat removal processes of these two sets were different while the charging processes were similar. In the first set of experiments, after the charging of the storage unit with relatively warm water was complete, heat removal process was started with simple heat exchangers from different elevations within the storage while the charging of the storage unit was continued. In the second set of experiments, after the charging of the storage unit was complete, heat removal from the storage unit was started without further charging of the storage unit. Charging water was fed into the storage from the top of one side and relatively colder water was drained from the bottom of the opposite side. Internal heat exchangers were used for the heat removal. Vertical temperature profile developments during the charging and heat removal periods were investigated. Thermal stratification was observed in all experiments. Heat exchangers extracted heat from different elevations in different experiments and the trend was that more heat can be extracted in upper elevations. Comparable heat can be extracted from the same elevation of lower and higher aspect ratio. Keywords: Sensible Heat Storage, Heat Removal, Thermal Stratification, Warm Water Storage

Cette étude porte sur les systèmes de stockage thermique régénératif dont le principe consiste à stocker de l’énergie sous forme de chaleur sensible dans un lit fixe. Le système est chargé et déchargé à l’aide d’un fluide caloporteur circulant à travers le lit fixe. Ce type de système est prometteur pour réduire le coût des infrastructures de stockage, par exemple dans les centrales solaires thermodynamiques. Cependant, le pilotage de ces systèmes est relativement complexe car leur fonctionnement est régi par divers phénomènes et met en jeux plusieurs modes de transfert de chaleur. Leur identification a permis de développer un modèle numérique monodimensionnel constitué d’une équation de continuité et de trois équations d’énergie : une pour le fluide caloporteur, une pour le solide du lit fixe et une pour les parois du réservoir. Les études expérimentales réalisées sur trois systèmes différents (un système huile/roches+sable, un système gaz/roches et un système gaz/céramique structuré en canaux), ainsi que des résultats issus de la littérature ont permis de valider le modèle proposé dans une large gamme de configurations. Le modèle s’avère notamment capable de traiter les fluides caloporteurs liquides ou gazeux et les lits fixes structurés en canaux ou constitués de milieux granulaires à granulométrie simple ou double. / This study deals with regenerative heat storage systems which aim to store sensible heat in a packed bed. The system is charged and discharged thanks to a heat transfer fluid which circulates through the packed bed. This kind of system is promising to reduce the cost of heat storage facilities, for example in concentrated solar power plants. However, the operation of these systems is relatively complex because their thermal behavior is governed by several phenomena and heat transfer modes. Thanks to the identification of these mechanisms, a one-dimensional numerical model consisting of one continuity equation and three energy conservation equations has been developed. There is one energy equation for the heat transfer fluid, one for the packed bed and one for the walls of the tank. The experimental studies carried out on three different systems (an oil/rock+sand system, a gas/rock system and a structured gas/ceramic system) and experimental results from the literature have enabled to validate the model in various configurations. The model is able to deal with liquid or gaseous heat transfer fluids and with structured packed beds with channels or granular packed beds with uniformly sized particles or particles of two different sizes.