Performance analysis of a brine-to-water heat pump and of its boreholes' temperature change during three years of operation

In the paper the analysis of a brine-to-water heat pump installation work for the central heating of an office building have been presented. The analysis covers three years of the system operation. The heat source of the system are vertical boreholes regenerated using various methods (passive and active). The measured data include the heating, electrical and cooling energy, the brine temperature and the sink temperature. In the paper, the impact of the regeneration method of the brine-to-water heat pump bore holes on the long-term boreholes' temperature changes was presented. The data showed that in the tested system the borehole without the active regeneration cools down about 0.8 K per year. The regenerated borehole does not cool down. Basing on the gathered data, the operation characteristic of the heat pump system efficiency was calculated. It was used in the simulations of the system's operation in two scenarios: with and without the active regeneration of the boreholes. The simulations showed a positive impact of the regeneration on the final efficiency of the tested heat pump system work at the level of 3% and 4% annually in the second and the third year of operation respectively. (C) 2017 Elsevier Ltd. All rights reserved.