Optimization of a Hybrid Ground Source Heat Pump using the Response Surface Method

A hybrid ground source heat pump (HGSHP) has been recommended as a low cost alternative of a ground source heat pump (GSHP) which has higher initial costs with increasing the size of ground heat exchanger (GHX) for imbalanced load conditions. HGSHP systems incorporate both GHX and supplemental equipments, such as cooling towers and/or boilers. The main issues of HGSHP are the optimal size design and control strategies of supplemental equipments. The objective of this paper is to optimize the size and control strategies using an optimization methodology called as the response surface method (RSM) to decrease the system’s total initial cost (IC) and/or life cycle cost (LCC) and/or annual energy use (AEU) of HGSHP systems. The simulation data used in this research was originated from Yavutzurk et al. and integrated with the RSM. Commercial software, which is Minitab 15, has been adopted to draw contour plots, surface plots and overlaid contour. With using response optimizer, the optimal size design and control strategies of supplemental equipments were determined individually and the results were compared with the results of Yavutzurk et al. The optimal size and control strategies have been successfully determined using the optimization tool of the RSM.