Pompes a chaleur geothermiques utilisant des banques thermiques a materiau a changement de phase

A detailed calculation methodology for the sizing of a vertical, closed loop geothermal borefield based on the ASHRAE method is presented. A building under construction located in Montreal is used as an example. This simple calculation procedure allows design engineers to conveniently size a geothermal heat exchanger without the use of specialized software.;The same building is used to estimate the impact of water tanks, used as short term thermal storage, on geothermal systems. The results of this study show that the length can be reduced by 15 % but that the impact on energy consumption is negligible. A new model of thermal storage tanks using phase change materials (PCM) is proposed for use within the TRNSYS environment. This one-dimensional transient model is based on the " enthalpy " method and considers a rectangular container filled with PCM. These containers are stacked such as to allow a heat transfer fluid to pass through them. The model is verified with analytical solutions and an inter model comparison is achieved with the " heat capacity " method. These verification tests show a very good agreement between the results. Finally, the proposed model is used to evaluate the impact of PCM thermal storage tanks on geothermal systems. TRNSYS simulations are run using the same building loads. Performances of the proposed PCM thermal storage tanks are compared to those of the water tanks previously studied. When compare to water tanks, PCM tanks can achieve a volume reduction of 69 %. The heat transfer processes between the PCM and the heat transfer fluid as well as within the PCM itself are also analyzed. Temperature distribution within the PCM at the entrance and exit of the tank and its influence on the heat transfer fluid for different times is presented.