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

Taewon Lee,Jihyun Hwang,Doosam Song

doi:10.3390/en14010031

Abstract

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.

Highlights

There is a global trend toward zero-energy buildings in order to minimize buildings’energy consumption and reduce carbon dioxide emissions
Since 2004, the South Korean government has mandated the installation of renewable energy systems, whereby a part of a building’s energy demand in terms of new construction, extension, or renovation of public buildings of equal to or larger than 1000 m2 is realized by renewable energy; this percentage increased from 10% in 2011 to 30% in 2020
The power consumption was calculated as the sum of the heat and circulation pumps (TLT ) heat storage tank was higher than that of the ground heat exchanger (GHE) outlet water in the afternoon

Summary

Introduction

There is a global trend toward zero-energy buildings in order to minimize buildings’energy consumption and reduce carbon dioxide emissions. As of 2020, the South Korean government has mandated the construction of new buildings with a total floor area of. Zero-energy buildings are buildings that waste less energy by having improved insulation and air-tightness, and minimize energy consumption through energy production using renewable energies, such as solar and geothermal energies. Solar and geothermal energies are renewable and can significantly contribute to achieving zero-energy buildings by generating energy on-site or off-site. Since 2004, the South Korean government has mandated the installation of renewable energy systems, whereby a part of a building’s energy demand in terms of new construction, extension, or renovation of public buildings of equal to or larger than 1000 m2 is realized by renewable energy; this percentage increased from 10% in 2011 to 30% in 2020. In South Korea, the installation of a geothermal heat pump system as a renewable energy system [1]

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Conclusion