Enhancing thermal efficiency of earth-air tunnel heat exchangers (EATHE) through response surface methodology

Abstract

This study investigates the optimization of Earth-Air Tunnel Heat Exchanger (EATHE) systems for maximizing air temperature reduction in Algeria's Timimoun region. Employing a Response Surface Methodology approach and Ansys Fluent 16.2 software, we meticulously analyze the influence of critical parameters on air temperature reduction: pipe depth, length, air velocity, and thermal conductivity of PVC and high-density polyethylene (HDPE) pipes. twenty-six simulations were conducted to optimize these parameters. The results reveal a significant influence of all investigated factors on air temperature reduction. Pipe depth emerged as the most influential factor, accounting for (56.22 %) of the temperature variance. This was followed by pipe length (28.26 %), air velocity (4.88 %), and pipe thermal conductivity (4.21 %). Based on these findings, we recommend prioritizing deeper placements (4 m), longer pipes (18 to 20 m), and air velocities below 3 m/s. For moderate-temperature applications, HDPE pipes offer a favorable choice.