Performance of a solar ground source heat pump used for energy supply of a separated building

Abstract

In order to achieve the carbon peak and carbon neutrality strategy in China, A SAGSHP (solar-assisted ground source heat pump) system is developed and four partition operation schemes of quarterly multi-mode switching buried pipe were designed in this research. Four types of buried pipe interconnection were schemed including central type, N type, H type, diagonal type, and the field tests were conducted. The system performance, soil heat balance, economic characteristics of the SAGSHP system were analyzed and compared with the ASHP&CFB (Air source heat pump & Coal-fired boiler) system. The results show that the energy supply by the SAGSHP system can meet the heating, cooling and domestic hot water needs of separated buildings after adopting the partitioned multi-mode switching operation scheme. Meanwhile, the system's heat loss is decreased, soil heat balance is well maintained, and the system flexibility is improved. The graded use of solar and soil energy is well realized. The COPs of SAGSHP system in heating period and cooling period were 3.62 and 5.76 respectively under the control of the central zoning operation scheme of buried pipes. Solar energy can provide 49.97 % of the total heat supply of the system. Compared with the ASHP&CFB system, the SAGSHP system can save 9.84 t of standard coal after operating 13 years, and the equivalent reductions of CO2, SO2, and dust are 26.568 t, 0.1968 t, and 0.1476 t, respectively. The system economy is the most sensitive to the project's initial cost whereas the least sensitive to electricity prices. The research in this paper provides a feasible alternative for the energy supply of separated office buildings in Chinese the severely cold regions of China.