Study on optimization of winter operation characteristics of solar-ground source heat pump in Shanghai

Abstract

The operational characteristics of the combined solar-ground source heat pump system (referred to as SGSHPS) are influenced by local solar resources, climate characteristics, and operating modes. This paper aims to study the operational characteristics of SGSHPS in Shanghai under different operation modes, providing a reference for engineering applications of SGSHPS.Three operation modes were selected for this study: operation of the soil source heat pump, tandem operation mode 1, and tandem operation mode 2. The tandem operation mode 1 represents the heat pump source-side outlet fluid passing first through the buried pipe and then through the thermal storage tank, The tandem operation mode 2 represents the heat pump source-side outlet fluid passing first through the thermal storage tank and then through the buried pipe. The highest system COP was experimentally measured for tandem mode 1. TRNSYS software was used to construct the three oeration modes and obtain parameters such as unit COP, system COP, and buried pipe heat exchange.By comparing and analyzing the winter typical january month average system COP values obtained from experiments and simulations for each operation mode, The maximum error between the experimentally derived conclusions and the simulated conclusions is 9.9 %. The winter typical month january average system COP for the operation of the soil source heat pump was 3.26, while for tandem mode 1 it was 3.5, and for tandem mode 2 it was 3.44. Tandem mode 1 exhibited a 7 % higher system COP compared to the operation of the soil source heat pump, and a 1.7 % higher system COP compared to tandem mode 2. This indicates that the tandem operation of the solar-ground source heat pump is more energy-efficient than the operation of the soil source heat pump system. Therefore, tandem mode 1 is considered the optimal operating mode for SGSHPS in Shanghai during winter.