A Parallelized Model For Simulating A Vertical Closed-Loop Geothermal Heat Pump System

Abstract

A borehole heat exchanger (BHE) is one of the important factors that can affect performance of the vertical closed-loop geothermal heat pump (GHP) system. Its construction costs are also a large percentage of the overall initial costs of the GHP system. When constructing BHEs, several parameters should be determined, such as length of the borehole heat exchanger, the number of the BHEs, and spacing between BHEs. Numerical simulation can be used to find optimal parameters. However, it takes a long time to find optimal parameters with a large domain. To reduce the calculation time, a massively parallel computing procedure is introduced into the serial simulator for the vertical closed-loop GHP system. It can simulate temperature changes in the BHE with circulating fluid through the U-tubes and compute groundwater flow and aquifer temperature changes. By increasing the number of processors, the total execution time was reduced from 7,031 seconds using two processors to 1,145 seconds using 32 processors. The total execution time of the serial model is 13,902 seconds.