DESIGN AND OPTIMUM CONTROL OF A SWEDISH DUALSOURCE (AIR AND GROUND) HEAT PUMP SYSTEM
The objective of this work is to evaluate if the combination of ambient air and the ground as heat source for heat pumps is technical and economical advantageous for heating only purposes. The simulation results of this study are based upon the actual design of a dual-source heat pump plant for a residential association area in the southwest of Sweden. The main finding is that a dual-source concept is to prefer when compared to just using ambient air or the ground as heat source for heat pumps. The study also show that increasing the number of boreholes or the size of the ambient air heat exchanger of the actual plant could be technical and economical beneficial. The control strategy used regarding ambient air temperature when switching between ambient air and the ground as heat source has only a minor influence of the plant performance. Due to economical reasons a control strategy without any recharging of the ground is also most advantageous in this case.