CFD Analysis of Thermal influence Zone of Earth Air Tunnel Heat Exchanger Under Transient Conditions

Thermal performance of Earth Air Tunnel Heat Exchanger (EATHE) under transient operating conditions depends upon the shape of thermal influence zone within the soil domain around the buried pipe. A detailed parametric analysis has been carried out using experimental and computational fluid dynamics (CFD) modeling to investigate the effect of time duration of continuous operation and thermal conductivity of soil on thermal influence zone under transient conditions. Results show that by giving due consideration on the thermal influence zone profile, excavation and back filling cost of EATHE trench may be reduced substantially. Study reveals that while laying the multiple pipes of EATHE one should not bury them in parallel configuration, rather depending upon soil thermal conductivity value and maximum duration of continuous operation, centre distance between two pipes must gradually decrease along the length.