Investigation of the Influence of Cross-Seasonal Heat Replenishment by a Cooling Tower on the Operational Characteristics of a Heating-Only Ground-Source Heat Pump System
DOI:
https://doi.org/10.65582/ec.2026.004Keywords:
Ground-source heat pump, Cooling tower, Heat replenishment, Hybrid system, Soil temperature, Thermal balance, Control strategyAbstract
To address soil cold accumulation in heating-only ground-source heat pump (GSHP) systems, this study proposes a cooling tower-assisted cross-seasonal heat replenishment method during the non-heating period. A residential district in Weifang was selected as the case study, and simulation models of both a heating-only GSHP system and a cooling tower-assisted hybrid GSHP system were established in TRNSYS. The long-term variations in soil temperature, borehole outlet water temperature, unit coefficient of performance (COP), and total system energy consumption were analyzed. In addition, two control strategies, namely time-based control and wet-bulb temperature difference control, were compared. The results show that cross-seasonal heat replenishment by the cooling tower can effectively slow the decline in soil temperature and improve the long-term operating conditions of the GSHP system. After 10 years of operation, the soil temperature of the hybrid system remained above 14 °C. Compared with the time-based control strategy, the wet-bulb temperature difference control strategy resulted in lower total system energy consumption, while both strategies maintained relatively stable heat pump performance. Under the conditions considered in this study, Strategy A4 showed a comparatively better overall balance between underground thermal maintenance and long-term energy consumption. These results provide a reference for the retrofit and operation optimization of heating-only GSHP systems in cold regions.
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