Developing a model for a geothermal heat pump

Abstract

Geothermal heat pump (GHP) systems represent a promising solution for sustainable heating and cooling applications, leveraging the stable temperature of the earth’s subsurface. However, these systems encounter two main drawbacks: high initial capital costs and the complexity involved in designing models to accurately predict system performance. Various models exist for vertical heat exchangers (VHEs), including analytical and numerical approaches. Analytical models rely on fundamental heat transfer principles and approximate boreholes as a single heat source, which limits their ability to accurately predict the outlet temperature of the heat exchanger. In contrast to analytical models, numerical methods, particularly 3D simulation software, provide better insights into modeling the complexity of vertical heat exchangers (VHEs). Although these programs can simulate heat exchanger outlet temperatures, they often require significant time and expertise, making them an unattractive choice for quick system analysis. This dissertation focuses on the development and validation of an intuitive computational model that can be used without the need of extensive research and aimed at accurately predicting the performance of a coaxial vertical heat exchanger(VHE). The developed model utilizes time and space discretization techniques to simulate the thermal process of the system and allows for the calculation of both the heat exchanger outlet temperature and also the temperature of the surrounding environment at very short time step intervals.