New generation of a highly compact solar heat pump system with boosted energetic efficiency

Abstract

In this work a new highly compact solar thermal heat pump system for space heating and domestic hot water preparation will be presented in detail. It was developed within the European project “MacSheep”. The aim of the project is to build four different solar heat pump systems, which achieve 25 % electric energy savings compared to the state of the art solar heat pump heating systems, while still being cost-competitive. Within the MacSheep project, four different developing groups developed different system concepts to reach this project goal. The system, which is presented in this paper, was developed and designed by the following partners; Energie Solaire SA (industrial partner), Institute of Thermal Engineering (research partner) and the Institute for Solar Technology SPF (research partner). A key component of the system is a novel brine-to-water heat pump prototype with a speed controlled compressor, an economizer refrigerant cycle and a desuperheater. The heat pump was optimized for low source temperatures, in order to be compatible with concepts that use only unglazed selective collectors as heat source. A key element was the integration of heat pump, storage, and hydraulic connections into one compact system design. Further developments are: a combi-storage, which is optimized for heat pump use, and selective unglazed c ollectors with a new selective coating. The compact designed heat storage, heat pump and hydraulic solution is placed under one high performing insulating shell built of vacuum insulation panels. The annual simulation results, which were validated with component tests in the lab, show very promising results for the whole system. The electric savings compared with the state of the art system are expected around 28 % and the improvement of the seasonal performance factor (SPF) of the whole system is around + 40 %. These values will be compared with a whole system hardware in the loop benchmark test in autumn 2015.