Experimental investigation of the performance of earth-to-air heat exchangers in arid environments

Earth-to-air heat exchanger (EAHE) is used for heating and/or cooling of dwelling and buildings in arid regions. In the present paper, experiments are performed to investigate the efficiency of an earth-to-air heat exchanger without external devices (fans, air blowers, etc.). The climatic conditions of the region of Bechar, which is located in the Southwest of Algeria, are considered. The EAHE is made of a PVC pipe with 66 m in length and 0.11 m in diameter. It was buried at a depth of 1.5 m in the agricultural zone, where the annual undisturbed subsoil temperature at 1.5 m is 28 degrees C. An increase of 19% in the relative humidity (RH) of EAHE has been observed in the humidification regime. While a decrease of 27% in RH has been reached in the dehumidification regime. For the hygrometric regime, the daily working regime was 62.5% of dehumidification (from 00 h to 09 h and from 18 h to 23 h) and 37.5% of humidification (from 10 h to 17 h). The EAHE technique has excellent potential for the enhancement of building hygrometry in arid regions.