The Effect of Soil Depth on the Performance of Earth Air Heat Exchanger for Climatic Condition of Baghdad, Iraq: Mathematical and Numerical Study

Geothermal energy is one of the important sources of renewable energy, so researchers are greatly interested in this type of energy. One of the advantages of this type of energy is its use to heat or cool buildings because the ground temperature is fairly constant throughout the year. The research focuses on understanding how soil depth affects the temperature difference, the rate of heat transfer, and the overall performance of the system in Baghdad, Iraq, throughout the year by conducting a mathematical test for the ground heat exchanger and determining the number of appropriate requirements during the study to reach an equation that simulates the distribution of temperatures at depth and time. The software package (CFD ANSYS FLUENT) version 17 was used for numerical analysis. The results showed that the heat transfer rate from air to soil for cooling purposes reached its highest value of-1375 watts during July at a depth of 6 m. As for heating purposes, the maximum value during January reached 579 watts at a depth of 10 m and 499 watts at a depth of 6m. Earth air heat exchanger effectiveness was highest possible at depths of 4 and 5 m, ranging from 0.9 to 0.92 over the year. The highest value of 0.98 for the exchanger effectiveness appeared during March. The results showed good agreement between the mathematical and numerical analysis and comparison with other studies, as the percentage of deviation ranged from 1.7% to 3.6% for depths from 1 m to 10 m.