CFD-Based Thermal Analysis and Experimental Validation of Pipe Materials in Earth Air Heat Exchangers for Energy-Efficient Buildings

The Earth Air Heat Exchanger (EAHE) harnesses geothermal energy to reduce cooling needs in the summer and heating demands in the winter. A heat transfer analysis was conducted using CFD Fluent's heating and cooling models to evaluate the performance of EAHE systems made from different pipe materials. The model is validated through experimental data collected from a test setup located in Ajmer, Western India, showing a strong correlation between simulation and real-world results. The thermal efficiency of helical pipe configurations made from various materials was assessed using CFD, focusing on changes in air temperature, the extent of heat exchange between the air and surrounding soil, and the thermal behavior at the knee point. During heating mode, a maximum air temperature rise of 13.56ºC was observed for air through copper and steel pipes, while a minimum temperature rise of 12.32ºC was achieved by air through an asbestos cement pipe. On the other hand, during the cooling of air maximum temperature drop of 19.68ºC was observed through the steel pipe, whereas a minimum temperature drop of 17.91ºC was observed for air through the asbestos pipe. During heating, the difference in temperature rise of the air through the poorest and best performing pipes is 1.24ºC, while during cooling, the difference in temperature drop of the worst performing and best performing pipes is 1.77ºC.