| Abstract | The purpose of this study is to conduct an experimental performance evaluation applying renewable heat sources to the cascade heat pump system compared to the air source in the winter. The renewable heat sources applied are geothermal and solar heat sources. The cascade heat pump supplies hot water from a high-cycle heat pump and air heating from a low-cycle heat pump. For the experiment, the cascade heat pump was manufactured and installed on the basement floor of the experimental building. The air source was supplied by an outdoor unit, the geothermal source by a geothermal simulator, and the solar source by a photovoltaic-thermal panel. The average value of the measured values for 10 minutes after the system was stabilized was used. The experimental results showed that applying renewable heat sources resulted in improved results in terms of heat capacity and supply fluid temperature, and the system COP was confirmed to have a performance improvement effect of 10.7% for the geothermal source and 6.1% for the solar source compared to the air source. This is the result of improved system performance while satisfying both the indoor heating load and the domestic hot water load flow rate. On the other hand, the temperature of the solar heat source was higher than that of the geothermal source, but low performance was derived. This is because the circulation flow of the solar heat source was circulated at 27% of that of the geothermal source, so relatively little heat was supplied to the heat pump. The cascade heat pump system of this study was installed with the indoor unit after the intermediate heat exchanger for domestic hot water. Therefore, a large amount of heat was supplied to the domestic hot water side. The performance of heating and domestic hot water can be affected depending on the installation order of the heat exchanger, regardless of the type and supply temperature of the heat source. |
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