Experimental study on cooling performance of underground pipe gallery ventilation enhanced by borehole heat exchanger

The underground pipe gallery (UPG) has the potential to provide pre-cooling for building ventilation. However, maintaining a stable air supply is challenging due to fluctuations in outdoor temperatures. To address this issue, a ventilation system that employs the UPG and the borehole heat exchanger (BHE) of a ground-source heat pump as integrated cooling sources is proposed in this study. The cooling performance and climate suitability of the newly designed system are experimentally evaluated by a full-scale setup. The results show the system has remarkable re-cooling effectiveness, maintaining room temperature below 28 °C even when outdoor temperatures exceed 40 °C. The BHE significantly cools the air from the UPG, thereby stabilizing air supply parameters. The temperature of the supplied air is consistently maintained between 18.7 °C and 20.9 °C, with a supply air flow rate ranging from 494.1 m³/h to 1982.9 m³/h. Based on the findings, the recommended ventilation rate is 494.1 m³/h, and the indoor thermal comfort satisfaction exceeds 60 % for occupants meeting the requirements (24 < T < 28 °C and 40 < RH < 70 %). The proposed system offers a viable alternative to traditional energy for building air conditioning with major technical benefits, particularly in arid regions.