Long-term energy and exergy analysis of heat pumps with different types of ground and air heat exchangers

Abstract

Heat pumps as the only end-use cooling/heating technology with a Coefficient of Performance (COP) greater than one, have attracted a great deal of attention over the past decade. In this study, the long-term energy and exergy analysis of four different types of heat pump systems: a common Air Source Heat Pump (ASHP), an ASHP with Ground Air Heat Exchanger (GAHE), a Ground Source Heat Pump (GSHP) with Horizontal Ground Water Heat Exchanger (HGWHE), and a GSHP with Vertical Ground Water Heat Exchanger (VGWHE) is performed. It is considered that all systems are used for space cooling and heating of a residential building. A mathematical model that takes into account the variations of building loads, ambient air temperature, soil temperature and COP of the system is developed for this purpose. The COP, the compressor work, and the exergy efficiency of the simulated systems are evaluated and compared over a thirty-year operating period. The obtained results indicated that the GSHP with the VGWHE demonstrated the best performance followed by the GSHP with the HGWHE, the ASHP with the GAHE and the common ASHP. Furthermore, the exergy destruction of each component of the simulated systems is evaluated and compared over a thirty-year operating period.