Experimental Study of the Annual Operation of an Air-soil Heat Exchanger in Ouagadougou

The use of air-soil heat exchangers for cooling habitats has developed considerably in recent years. An air-soil heat exchanger (ASHE) is a geothermal system that uses the thermal inertia of the soil to heat or cool part of the air to renew a habitat. It is sometimes called a Canadian well or a Provencal well. In this present work, we have presented the experimental prototype implemented in Ouagadougou. It is an air-soil heat exchanger consisting of a U-shaped PVC pipe of horizontal length 15 m, diameter 16 cm and placed at a depth of 1.5m (slope of about 2%) in floor. The experimental work consists in measuring, on the one hand, the temperature of the air from the inlet of the tube to the outlet in steps of 2 m in length and, on the other hand, the temperatures of the ambient air, air in the habitat and soil at 1 m and 1.5 m depth. This study has allowed analyzing the evolution of air temperatures in the system. The thermals performances of air-soil heat exchanger have been also evaluated and his influence on air temperature in the habitat. The results show that the experimental setup is of good quality. In practice, the thermal efficiency is between 20% and 70%.