Experimental study of an earth to air heat exchanger (EAHE) for warm humid climatic conditions

This work presents an experimental study of an Earth-Air Heat Exchanger (EAHE) under a warm humid weather conditions of Mexico. The EAHE has a horizontal configuration with three sections of 101.6 mm diameter PVC pipe, a horizontal pipe of 6 m long and two vertical sections of 3 m long for the inlet and outlet sections. It was buried at 2.5 m and to improve the performance of the EAHE, the outlet section was thermally insulated. We monitored for 6 months the soil temperature from 0 to 2.5 m in intervals of 0.25 m, and the air temperature at the inlet and the outlet. Specific heat was determined for five samples of soil analyzed using thermogravimetry. The average temperature of the soil at 2.5 m depth remained between 27-28 degrees C, and the obtained specific heat of the soil ranged between 0.726 and 0.910 Jg(-1)K(-1) showing a homogeneous behavior. The EAHE behaved as a cooler during the day and as a heater at night, except in the winter season that worked most of the time as a heater. The EAHE had a temperature difference as a cooler of 5.5 degrees C. The maximum energy removed as a cooler was of 4.438 kWh for August. The results show that with the EAHE it is possible to cool an airflow under humid-warm weather conditions.