Research on water–ice heat accumulator and analysis of its potential use as hybrid source heat pump for building heating

This paper presents an experimental and analytical study of the effects of the integration of a prototype heat accumulator using water–ice latent heat as an additional hybrid low-temperature heat source for an air source heat pump (HSHP). The study was conducted in two stages. The first stage involved experimental studies on the charging and discharging processes of the prototype accumulator. The second stage was the determination of the possible energy and economic effects of using the proposed hybrid heat source for a single-family building with a thermal output of 7.9 kW. The waste heat from ventilation and gray wastewater was used to charge the studied heat accumulator. A comparative analysis of the HSHP system with two classic solutions—an air source heat pump system (ASHP) and a ground source heat pump (GSHP)—was performed. The results indicated that the HSHP system had 21% and 5% lower electricity demand than ASHP and the GSHP, respectively. An additional benefit of the developed solution was the utilization of 58% of the waste heat of the building, which accounted for 33% heating demand coverage. Economic analysis suggested that the developed HSHP system was a lower cost solution than the GSHP in terms of the investment and operation costs.