A transient two-dimensional finite volume model for the simulation of vertical U-tube ground heat exchangers

The ability to predict both the long-term and short-term behavior of ground loop heat exchangers is critical to the design and energy analysis of ground source heat pump systems. A numerical model for the simulation of transient heat transfer in vertical ground loop heat exchangers is presented. The model is based on a two-dimensional fully implicit finite volume formulation. Numerical grids have been generated for different pipe sizes, shank spacing and bore-hole sizes using an automated parametric grid generation algorithm. The numerical method and grid generation tech-niques have been validated against an analytical model. The model has been developed with two main purposes in mind. The first application is use in a parameter estimation tech-nique used to find the borehole thermal properties from short time scale test data. The second application is the calculation of nondimensional temperature response factors for short time scales that can be used in annual energy simulation.