A Study on Optimization of Grid-Layout Earth-to-Air Heat Exchangers (EAHEs) at Constant Total Heat Transfer Surface by using Taguchi Method

The earth-to-air heat exchanger (EAHE) is a remarkable passive system that utilizes the earth’s energy for ventilation of air circulating through buried tubes which can lead to a significant reduction in building energy consumption. EAHE’s thermal performance can be affected by the system configuration. The present study optimizes the thermal effectiveness and thermohydraulic performance factor (TPF) of U-type grid-layout EAHEs at constant total heat transfer surface using the Taguchi technique for cooling applications. For this purpose, four important factors were selected including the diameter of branch tube, diameter of main tube, number of branch tubes, and volumetric airflow rate that were taken at four different levels. The best combination for achieving maximum thermal effectiveness and TPF of U-type grid-layout EAHEs was obtained. The research results reveal that the highest effective factor for thermal effectiveness and TPF was the diameter of the branch tube with contributions of 72% and 40.6%. Also, the lowest effective factors were the volumetric airflow rate and diameter of the main tube with contributions of 1.1% and 14.7%, respectively.