A TRNSYS/GROCS Simulation of a Horizontal Coil Ground-Coupled Heat Pump

The ground-coupled heat pump system in TECH House I at the University of Tennessee has been modelled using TRNSYS/GROCS and the results have been compared with actual performance data for both the 1982–83 heating season and the 1983 cooling season. Hourly measurements of various ground temperatures, conditioned space temperatures, power requirements and heat transferred to or from the ground and the conditioned space were made. Results indicate that the model prediction is within 5 percent of the measured seasonal performance factor for both the summer and winter season. Parametric studies were undertaken to examine the effect of ground coil length, soil thermal conductivity, and the heat pump performance rating on the overall seasonal performance of the system. Overall performance is shown to increase with improved performance and increased soil thermal conductivity while the coil length shows an optimum value due to the increase of pumping power with length.