Experimental investigation and control optimization of a ground source heat pump system

This paper presents an experimental investigation and control optimization of a ground source heat pump (GSHP) system. A set of experimental tests was first carried out to examine the performance of the GSHP system under different ground loop differential pressure set-points and different configurations of the ground heat exchangers (GHEs). A model-based optimization strategy was then developed to determine the optimal operating speed of the variable speed pumps in the ground loop system, in which a hybrid optimization technique integrating a performance map-based near-optimal strategy and the exhaustive search method was used to search for the optimal solutions of the optimization problem. The results from the experiments showed that, for the GSHP tested, the coefficient of performance (COP) of the heat pump units increased while that of the whole GSHP system decreased with the increase of the ground loop differential pressure set-point. The GSHP system with GHEs in the parallel operation outperformed that in the series operation. Using the proposed model-based strategy, energy savings of 8.0% during the heating period, and 9.0% during the cooling period can be achieved in comparison to a rule-based strategy with two-stage control for variable speed pumps