In this thesis, heat and moisture transfer between supply and exhaust air streams are investigated for a run-around system in which the coupling material is a desiccant coated solid that is transported between two exchangers. The finite difference method is used to solve the governing partial differential equations of the cross-flow heat exchangers in the supply and exhaust ducts. The outlet air properties are calculated for several inlet air operating conditions and desiccant properties. The accuracy of the heat transfer model is verified by comparing the simulations with well-known theoretical solutions for a single cross flow heat exchanger and a liquid coupled run-around system. The difference between the analytical predictions and the numerical model for sensible effectiveness for each exchanger and the run-around system were found to be less than 1% over a range of operating conditions. The model is also verified by modifying the boundary conditions to represent a counter flow energy wheel and comparing the calculated sensible, latent, and total effectiveness values with correlations in the literature. <p>Using the verified model for energy exchangers and the run-around energy recovery system, the sensible, latent and overall effectiveness are investigated in each exchanger and the run-around system during simultaneous heat and moisture transfer. The overall effectiveness of the run-around energy recovery system is dependent on the air flow rate, the solid desiccant flow rate, the desiccant properties, specific surface area, the size of each exchanger, and the inlet air operating conditions. The run-around system can achieve a high overall effectiveness when the flow rates and exchangers properties are properly chosen. Comparisons between the solid desiccant and salt solution run-around system effectiveness (Fan, 2005 and Fan et al, 2006) shows they are in good agreement. In a sensitivity study, the thickness of desiccant on the fibre is investigated in the solid run-around system. It was found that good performance is obtained with very thin desiccant coatings (1 or 2 micron). During the practical use of this system, a desiccant coated fibre could be inserted into very porous balls or cages that protect the desiccant coated fiber from mechanical wear. The performance sensitivity for this kind of run-around system is demonstrated.

In this thesis, heat and moisture transfer between supply and exhaust air streams are investigated for a run-around system in which the coupling material is a desiccant coated solid that is transported between two exchangers. The finite difference method is used to solve the governing partial differential equations of the cross-flow heat exchangers in the supply and exhaust ducts. The outlet air properties are calculated for several inlet air operating conditions and desiccant properties. The accuracy of the heat transfer model is verified by comparing the simulations with well-known theoretical solutions for a single cross flow heat exchanger and a liquid coupled run-around system. The difference between the analytical predictions and the numerical model for sensible effectiveness for each exchanger and the run-around system were found to be less than 1% over a range of operating conditions. The model is also verified by modifying the boundary conditions to represent a counter flow energy wheel and comparing the calculated sensible, latent, and total effectiveness values with correlations in the literature. <p>Using the verified model for energy exchangers and the run-around energy recovery system, the sensible, latent and overall effectiveness are investigated in each exchanger and the run-around system during simultaneous heat and moisture transfer. The overall effectiveness of the run-around energy recovery system is dependent on the air flow rate, the solid desiccant flow rate, the desiccant properties, specific surface area, the size of each exchanger, and the inlet air operating conditions. The run-around system can achieve a high overall effectiveness when the flow rates and exchangers properties are properly chosen. Comparisons between the solid desiccant and salt solution run-around system effectiveness (Fan, 2005 and Fan et al, 2006) shows they are in good agreement. In a sensitivity study, the thickness of desiccant on the fibre is investigated in the solid run-around system. It was found that good performance is obtained with very thin desiccant coatings (1 or 2 micron). During the practical use of this system, a desiccant coated fibre could be inserted into very porous balls or cages that protect the desiccant coated fiber from mechanical wear. The performance sensitivity for this kind of run-around system is demonstrated.

This study focuses on the hygrothermal performance of Moso bamboo. The knowledge in this aspect is remarkable important for the research of building energy saving and the low carbon building design. However, the detailed hygrothermal properties of Moso bamboo are fairly rare. To obtain these data, a series of experimental works have been done for measurement of density, porosity, thermal conductivity, specific heat capacity, water vapour permeability, hygrothermal expansion and sorption isotherm of Moso bamboo. To obtain further understanding on the hygrothermal performance of Moso bamboo, a number of dynamic heat and moisture transfer experiments were conducted. These experiments simulated two extreme outdoor environments and one indoor environment. The temperature and RH responses of Moso bamboo panels were monitored. Then a coupled transient heat and moisture transfer numerical simulation at the material level was conducted to predict and validate the hygrothermal performance of Moso bamboo. A sensitivity study of the hygrothermal properties of bamboo was also presented to indentify the influence of each hygrothermal property of Moso bamboo. Major findings include the following aspects. Both experiment and simulation results appear to be consistent with the results of measurements of the basic hygrothermal parameters. The parametric study found that density can be regarded as the most sensible parameter to influence the temperature simulation results at the transient state, while the thermal conductivity dominated the temperature variation at the steady state. The water vapour diffusion resistance factor can be regarded as the most critical parameter to influence the RH simulation results. The influence of liquid water diffusivity is negligible in this study. The parametric study results indicated that the simulation with moisture is more accurate than the simulation without moisture in both equilibrium and transient state. The results also imply that the existence of moisture could increase the heat capacity and reduce the thermal conductivity. The results of this study recommend that the external part of the bamboo culm wall can be utilised to minimise the RH variation of the panel while the internal part of the bamboo culm wall is suitable to increase the thermal insulation performance of the panel. To avoid hygroexpansion, the implementation of external part of bamboo culm wall needs to be minimised.

Le béton de chanvre est un matériau de construction biosourcé pouvant répondre aux problématiques environnementales actuelles. Utilisé comme matériau de remplissage avec une bonne capacité isolante, il possède également la capacité de réguler l'humidité relative intérieure. Son comportement hygrothermique complexe résulte notamment de performances thermiques et hydriques interdépendantes. La prédiction de ces effets est réalisée à l'aide de modélisation et simulation de transferts hygrothermiques. Toutefois, l'utilisation de données d'entrée les plus représentatives possibles de la réalité est nécessaire. Les méthodes de caractérisation courantes ont souvent été développées pour des matériaux conventionnels et peuvent montrer des limites dans le cas de matériaux biosourcés. L'objectif principal de ces travaux est de déterminer les propriétés hygrothermiques d'un bloc de béton de chanvre préfabriqués à l'échelle industrielle, de mieux appréhender cette caractérisation et de décrire son comportement hygrothermique via des simulations numériques. Le matériau étudié est formulé à partir d'un liant pouzzolanique et de granulats de chènevotte. Une partie de ce travail de thèse a donc porté sur la caractérisation des propriétés physiques, thermiques et hydriques du béton de chanvre étudié ainsi que sur les méthodes de mesure. Pour chaque paramètre hygrothermique étudié, plusieurs méthodes ont été confrontées afin d'en évaluer l'impact. Dans la mesure du possible, l'influence de la température et de l'humidité sur les différents paramètres a également été estimée. Un modèle de transferts hygrothermiques est proposé avec une évaluation d'ordre de grandeur dans le cas du béton de chanvre à partir des propriétés de la littérature. Ce modèle est appliqué à une étude expérimentale à l'échelle de la paroi, dans une enceinte bi-climatique, mettant en avant l'impact de la sorption et du changement de phase sur les transferts de chaleur. En ce qui concerne les propriétés thermiques, l'étude expérimentale à l'échelle du matériau met en évidence l'impact significatif du protocole expérimental sur le résultat de mesure, en particulier pour la chaleur massique. Pour les propriétés hydriques, les essais mettent en avant l'intérêt de réaliser une étude paramétrique de type round-robin sur les matériaux biosourcés. [...] / Hemp concrete is a bio-based construction material able to meet current sustainable issues. Used as filling and insulating material, it has the capacity to regulate the indoor relative humidity. Its complex hygrothermal behavior results on interdependent thermal and hydric performances. The prediction of the hygrothermal effect is performed through heat and moisture transfer modeling and simulation. However, the use of representative inputs is necessary. Standard characterization methods have often been developed for usual building material and can show some limitations in the case of bio-based material. The main objective of these works is to determine the hygrothermal properties of a precast hemp concrete produced at industrial scale, have a better understanding of this characterization and describe its hygrothermal behavior through numerical simulations. The studied material is based on pozzolanic binder and hemp aggregates. One part of this work deals with the characterization of the physical, thermal and hydric properties of the studied material and with the measurement methods. For each hygrothermal properties, several methods have been confronted. If possible, the temperature and humidity influences have been appraised. A heat and moisture transfer model is proposed with a scale analysis based on hemp concrete properties from the literature. This model has been applied to wall scale experiments highlighting the impact of sorption and phase change phenomena on the heat transfers. With regards to the thermal properties, the experimental study at material scale highlights the significant impact of the experimental protocol on the result of the measure, particularly for the specific heat capacity. For hydric properties, the studies put forward the interest of performing a parametric round-robin test dedicated to bio-based materials. An air permeability measurement protocol designed for regular concrete has been adapted in order to evaluate the performance of a very permeable material such as the hemp concrete. The numerical model is validated on a test from a standard and a test from the literature. It manages to describe test with usual ambient solicitations performed in the bi-climatic chamber.

With the rise in hazards that structures are potentially subjected to these days, ranging from pre-contemplated terror attacks to accidental and natural disasters, safeguarding structures against such hazards has increasingly become a common design requirement. The extreme loading conditions associated with these hazards renders the concept of imposing generalized codes and standards guidelines for structural design unfeasible. Therefore, a general shift towards performance-based design is starting to dominate the structural design field. This study introduces a powerful structural analysis tool for reinforced concrete structures, possessing a high level of reliability in handling a wide range of typical and extreme loading conditions in a sophisticated structural framework. VecTor3, a finite element computer program previously developed at the University of Toronto for nonlinear analysis of three-dimensional reinforced concrete structures employing the well-established Modified Compression Field Theory (MCFT), has been further developed to serve as the desired tool. VecTor3 is extended to include analysis capabilities for extreme loading conditions, advanced reinforced concrete mechanisms, and new material types. For extreme loading conditions, an advanced coupled heat and moisture transfer algorithm is implemented in VecTor3 for the analysis of reinforced concrete structures subjected to fire. This algorithm not only calculates the transient temperature through the depth of concrete members, but also calculates the elevated pore pressure in concrete, which enables the prediction of the occurrence of localized thermally-induced spalling. Dynamic loading conditions are also extended to include seismic loading, in addition to blast and impact loading. Advancing the mechanisms considered, VecTor3 is developed to include the Disturbed Stress Field Model (DSFM), dowel action and buckling of steel reinforcement bars, geometric nonlinearity effects, strain rate effects for dynamic loading conditions, and the deterioration of mechanical properties at elevated temperatures for fire loading conditions. Finally, the newly-developed Simplified Diverse Embedment Model (SDEM) is implemented in VecTor3 to add analysis capability for steel fibre-reinforced concrete (SFRC). Various analyses covering a wide range of different structural members and loading conditions are carried out using VecTor3, showing good agreement with experimental results available in the literature. These analyses verify the reliability of the models, mechanisms, and algorithms incorporated in VecTor3.

With the rise in hazards that structures are potentially subjected to these days, ranging from pre-contemplated terror attacks to accidental and natural disasters, safeguarding structures against such hazards has increasingly become a common design requirement. The extreme loading conditions associated with these hazards renders the concept of imposing generalized codes and standards guidelines for structural design unfeasible. Therefore, a general shift towards performance-based design is starting to dominate the structural design field. This study introduces a powerful structural analysis tool for reinforced concrete structures, possessing a high level of reliability in handling a wide range of typical and extreme loading conditions in a sophisticated structural framework. VecTor3, a finite element computer program previously developed at the University of Toronto for nonlinear analysis of three-dimensional reinforced concrete structures employing the well-established Modified Compression Field Theory (MCFT), has been further developed to serve as the desired tool. VecTor3 is extended to include analysis capabilities for extreme loading conditions, advanced reinforced concrete mechanisms, and new material types. For extreme loading conditions, an advanced coupled heat and moisture transfer algorithm is implemented in VecTor3 for the analysis of reinforced concrete structures subjected to fire. This algorithm not only calculates the transient temperature through the depth of concrete members, but also calculates the elevated pore pressure in concrete, which enables the prediction of the occurrence of localized thermally-induced spalling. Dynamic loading conditions are also extended to include seismic loading, in addition to blast and impact loading. Advancing the mechanisms considered, VecTor3 is developed to include the Disturbed Stress Field Model (DSFM), dowel action and buckling of steel reinforcement bars, geometric nonlinearity effects, strain rate effects for dynamic loading conditions, and the deterioration of mechanical properties at elevated temperatures for fire loading conditions. Finally, the newly-developed Simplified Diverse Embedment Model (SDEM) is implemented in VecTor3 to add analysis capability for steel fibre-reinforced concrete (SFRC). Various analyses covering a wide range of different structural members and loading conditions are carried out using VecTor3, showing good agreement with experimental results available in the literature. These analyses verify the reliability of the models, mechanisms, and algorithms incorporated in VecTor3.

Les bétons légers, formés des fibres de bois et d’une pâte de ciment Portland, constituent une nouvelle alternative à explorer pour réduire l’impact environnemental des bâtiments. Ils sont utilisés dans la construction durable, comme des éléments secondaires, pour leurs performances thermiques, hydriques et mécaniques. Cependant, la généralisation de leur utilisation dans le bâtiment ne sera rendue possible sans résoudre certains verrous scientifiques liés à leur caractérisation et à leur formulation. Le présent travail s’inscrit dans cet objectif. Il s’agit de contribuer à la caractérisation de ces bétons légers à base des fibres de bois à travers l’expérience et la modélisation. Le module d’Young et la résistance à la rupture ont été mesurés par des tests de flexion et de compression. Un modèle numérique a été également développé pour prédire le comportement des éprouvettes en flexion et la réponse structurale des systèmes de coffrage permanent. La méthodologie numérique permet ainsi d’aider dans le choix des paramètres optimums pour une meilleure conception des panneaux de coffrage destinés à la construction. L’étude du comportement hygrothermique du matériau de construction bois-ciment a été abordée en s’appuyant sur l’expérience et la simulation. Les équations des transferts couplés de chaleur et d’humidité d’un milieu poreux ont été implémentées dans le logiciel Comsol Multiphysics®. En dernier, le modèle développé a été appliqué et validé sur plusieurs réponses dynamiques issues des tests hygrothermiques réalisés en interne. Les mesures des propriétés physico-thermique du matériau composite bois-ciment ont été ensuite intégrées dans le code Abaqus via une routine utilisateur Umatht dans l’objectif de simuler le comportement thermique à hautes températures des panneaux composites bois-ciment. Les profils des températures sont évalués et comparés à ceux des tests de carbonisation réalisés, à l’aide d’un panneau rayonnant, sur des échantillons exposés à un flux de chaleur uniforme de 6kW/m2. Les simulations montrent que le modèle développé est capable de prédire les profils de températures, la zone et la profondeur de la couche du charbon durant l’exposition au feu / Lightweight concretes made from wood fibres and Portland cement paste are a new alternative for the reduction of the environmental impact of buildings. They are used in sustainable constructions as secondary elements for their thermal, hydric and mechanical performance. However, the generalisation of their use is not possible without resolving certain scientific obstacles related to their characterisation. Hence the aim of the present work, which is to contribute towards their characterisation through experimentation and numerical simulation. The Young's modulus and tensile strength were measured through flexural and compression tests. A numerical model has also been developed to predict the behaviour of specimens under bending test as well as their structural response when used as permanent formwork. In particular, the model helps to choose the optimum parameters for a better design of the formwork system. The study of the hygrothermal behaviour of the wood-cement material was carried out using both experimental work and simulation. The equations of coupled heat and moisture transfers for a porous medium have been implemented in the Comsol Multiphysics® software. The developed model has been applied and validated on several dynamic responses resulting from hygro-thermal tests carried out in the laboratory. The obtained physico-thermal properties of the wood-cement composite material were then incorporated into the Abaqus code via a Umatht user subroutine to simulate its high temperature behavior. The temperature profiles are evaluated and compared with the charring tests performed using a radiant panel on samples exposed to a uniform heat flux of 6kW/m². The simulations show that the developed model is able to predict the temperature profiles, the area and the depth of the charred layer during fire exposure

Ce travail concerne la modélisation numérique et expérimentale de la variabilité des propriétés thermo-hydriques de matériaux cimentaires en vue de l’évaluation de son impact sur la prédiction du comportement hygrothermique de parois de bâtiments. Une approche probabiliste qui prend en compte la variabilité spatiale des propriétés de matériaux lors des transferts couplés de chaleur et d’humidité a été développée. Elle est basée sur la génération, par la décomposition modale de Karhunen-Loève, de champs aléatoires spatialement corrélés. Une implémentation d’un modèle de transfert hygrothermique dans un code de simulation numérique a été ensuite réalisée en adoptant cette démarche stochastique. Cette dernière, qui considère comme variables d’entrée des champs aléatoires, permet de quantifier l’incidence de cette variabilité sur le comportement hygrothermique d’une paroi de bâtiment. Une étude préalable, dédiée à l’évaluation de l’incidence de la variabilité aléatoire du coefficient de diffusion, a été entreprise en considérant une variabilité de ±30% pour un mortier et de ±20% pour un BHP suivant une loi de distribution normale. Aussi, nous avons relevé un certain nombre d’incertitudes possibles de la teneur en eau à saturation tout en montrant leurs effets sensibles sur le résultat de la prédiction du comportement hygrothermique. Ces études ont permis de mettre en exergue l’importance de la prise en compte des incertitudes sur les données du matériau lors des simulations numériques des transferts hygrothermiques. Sur le plan expérimental, une campagne d’évaluation de la variabilité spatiale des paramètres les plus influents a été menée. Cette campagne a été réalisée sur un voile de dimension 2x1,2 m fabriqué au laboratoire. À l’issue de ce programme expérimental, l’espérance, la variance et la longueur de corrélation des propriétés étudiées (porosité à l’eau, perméabilité à la vapeur, isotherme de sorption et perméabilité au gaz) ont été déterminées. Ces trois paramètres sont indispensables pour la bonne mise en œuvre de la décomposition de Karhunen-Loève. Aussi, une autre campagne de caractérisation expérimentale a été menée sur des pâtes de ciment, mortiers et béton. Elle a été divisée en trois grandes parties selon les propriétés étudiées : (i) Les propriétés microstructurales et d’hydratation où l’on retrouve les mesures des porosités à l’eau et au mercure ainsi que les distributions de la taille des pores et une analyse de l’effet du taux d’hydratation de matériaux cimentaires sur leurs propriétés hygrothermiques. (ii) Les propriétés hydriques : dans cette partie, une analyse sous différents angles (évolution en fonction de l’âge des matériaux, en fonction de la température, effet des constituants des matériaux, etc.) a été réalisée sur les isothermes de sorption et sur la perméabilité à la vapeur d’eau. (iii) Les propriétés thermiques où des mesures de conductivités thermiques et de chaleurs spécifiques ont été effectuées. Les résultats de l’étude ont mis en exergue les limites des approches déterministes suite à leurs confrontations avec les résultats obtenus par l’approche probabiliste, mise en œuvre dans le cadre du présent travail. / This study deals with the experimental and the numerical modeling of the variability properties of cement based materials to evaluate their effects on the prediction of hygrothermal behavior of building envelops. A probabilistic approach taking into account the spatial variability of the materials properties during the coupled heat and mass transfer has been developed. It is based on the generation of spatially correlated random fields by the Karhunen Loève decomposition. The stochastic model’s program has been implemented in a numerical simulation code. Using this tool that considers the input variables as random fields, the impact of this variability on the hygrothermal behavior of building envelops was quantified. A prior study dealing with the assessment of the effect of the diffusion coefficient random variability was carried out by considering a variation of ±30% for mortar and ±20% for high performance concrete (HPC) according to a normal distribution. Also, we have identified some possible uncertainties of the water content at saturation and showed their significant impact on the prediction of hygrothermal behavior of the material. These studies highlight the importance of considering the data uncertainties of building materials during numerical simulation of hygrothermal transfers. At the experimental level, the spatial variability of the most influential parameters was evaluated. It was carried out by manufacturing a concrete wall in lab. At the end of this experimental program, the expected value, standard deviation and the correlation length of the studied properties (water porosity, water vapor permeability, sorption isotherm and gas permeability) were determined. These three parameters are important for the successful implementation of Karhunen Loeve decomposition. Also, another experimental program was conducted on cement pastes, mortars and concrete. It was divided into three parts according to the studied properties:(i) Hydrations and microstructural properties which include the measurement of water and mercury porosity, the pore size distributions and an analysis of some techniques for stopping cement hydration.(ii) Hydric properties: where an analysis of the sorption and the water vapor permeability was performed considering their evolution with materials ages, temperature…(iii) Thermal properties where measurement of specific heat and thermal conductivity were performed. The result of the study highlighted the limits of deterministic approaches after their confrontation with the obtained results using the probabilistic one developed in this work.