Investigation on the thermal performance of the diaphragm wall in deep buried engineering: a simulation study

Abstract

Ground source heat pump technology is widely used in buildings’ to meet the cooling and heating demand. As a special form of the buried pipe, diaphragm wall has received increasing interests due to high energy-efficiency and relatively low costs. Previous studies investigated the thermal behavior of diaphragm wall in underground tunnels or underground parking while very few studies were carried out on deep-buried engineering with the air-conditioned adjacent indoor environment. In this study, the effects of buried pipes on the heat transfer regulation of the diaphragm wall and the indoor load are analyzed. Simulation results indicated that average energy exchange through the pipe in the diaphragm wall is 78.1% compared with that of the conventional buried pipe for the ground heat pump. The heat exchange capacity of the buried pipe in the diaphragm wall in intermittent mode is 1.2 times of that in the non-intermittent mode in 14h. For the underground engineering boundary with pipes buried in the concrete layer, heat transfer through the inner surface reduced 3.8W/m2, which would consequently add to the indoor cooling load. In order to reduce the heat transfer back to the indoor environment through the inner surface, insulation of the diaphragm wall are analyzed. This study can provide a reference for the analysis of the feasibility and application of diaphragm wall in deep-buried engineering.