Ground-source heat pumps, coupled to vertical geothermal boreholes, are an energy-efficient method to meet the heating and cooling loads of buildings. In cold climates, ground-source heat pumps will gradually exhaust the ground thermal energy stores, resulting in lower returning fluid temperatures from the boreholes. A colder returning fluid temperature will typically cause a drop in heat pump efficiency. If the fluid temperature drops too low, the heat pump will no longer be able to operate safely or efficiently. A similar effect is seen in cooling-dominated buildings, where returning fluid temperatures gradually rise. The simulation of ground-source heat pump systems aims at predicting the returning fluid temperatures from geothermal boreholes and the ground temperatures in the bore field. The accurate prediction of these temperatures is critical to the evaluation of the ground-source heat pump performance and to the proper design of the system, i.e. the evaluation of the required borehole length and bore field layout to satisfy the building thermal demand.
The heat transfer process in bore fields evolves over several time and spatial scales. At short time scales (i.e. from minutes to hours), the effects of the transit of the fluid through the boreholes and transient heat conduction through the grouting material dominate the heat transfer process. At medium time scales (i.e. from weeks to months), thermal interference between the boreholes becomes significant. At long time scales (i.e. after several years), heat conduction in the ground becomes three-dimensional and boreholes see significant axial temperature variations. This seminar presents recent developments in simulation techniques for ground-source heat pump systems and demonstrates how these techniques are deployed to create accurate and computationally efficient simulation models.
Short biography of dr. ir. Massimo Cimmino
Ph.D. Massimo Cimmino is an Assistant Professor in the Department of Mechanical Engineering at Polytechnique Montréal (Canada). He has been conducting research on the topic of ground-source heat pump systems since 2011. His PhD work focused on model development and model validation of long-term heat transfer in geothermal heat exchangers. His current research interests are heat pumps & refrigeration, thermal energy storage, thermal energy networks, energy simulation tools, and geothermal energy. He recently received the ASHRAE Kirk T. Mescher