Effect of operational strategy on thermal response of a model energy diaphragm wall

The development of energy diaphragm walls (wall heat exchangers) provides a new perspective for the shallow geothermal energy exploitation. This study conducted a series of thermal performance tests on a model energy diaphragm wall, focusing on the effects of different relative temperature differences and operation modes, which closely aligned with the practical use of ground-source heat pump systems. The results indicate that increasing the relative temperature difference from 15 °C to 30 °C enhanced the wall's thermal efficiency and total heat exchange by 108.2 % and 116.2 %, respectively. Importantly, intermittent operation achieved a 35.7% maximum improvement in thermal efficiency compared to continuous operation. Thermal response analysis further revealed uneven temperature distribution across the wall and intense thermal coupling with the adjacent excavation space. Finally, the study proposes recommendations to optimize experimental designs and advance practical implementations of energy wall systems in geothermal projects.