The Effect of Coupling Solar Thermal System and Geothermal Heat Pump Systems in Areas with Unbalanced Heating and Cooling Demand

• Main Authors: Jihyun Hwang, Doosam Song, Taewon Lee
• Format: Article
• Language: English
• Published: MDPI AG 2021-12-01
• Series: Energies
• Subjects: geothermal source heat pump; solar thermal system; heating; coupling; performance analysis
• Online Access: https://www.mdpi.com/1996-1073/14/1/31

Geothermal source heat pump (GSHP) systems as renewable energy systems are being more frequently installed as part of the zero-energy building drive. However, in South Korea, where a large amount of heating load can be required, maintaining high system performance by using only a GSHP is difficult owing to the gradual degradation of its thermal performance. The performance of a solar-assisted GSHP system was therefore experimentally analyzed and compared with a GSHP-only system. The results showed that the heating coefficient of performance of the GSHP-only operation was 5.4, while that of the solar-assisted GSHP operation was 7.0. In the case of the GSHP-only system, the maximum temperature of the heat pump water supply on the heat source side was initially 13.1 °C, but this rapidly decreased to 11.4 °C during operation. For the solar-assisted GSHP system, the temperature of the water supply to the heat source side of the heat pump was controlled at 15–20.9 °C, and the power consumption for system operation was reduced by about 20% compared with that for the GSHP-only system. Much higher temperatures could be supplied when solar heat is used instead of ground heat, as solar heat contributes to the performance improvement of the heat pump system.