30 May 2005

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.