Study of the parameters influencing the thermal performances of an earth-to-air heat exchanger used in cooling mode

The geothermic low temperature can be used to produce the fresh air with the help of an adequate heat exchanger. This last one is often constructed from a pipe in PVC buried in soil and in which we make circulate the ambient hot air. Certainly, the air outlet temperature depends on the climatic conditions of the site and the geometric and dynamic parameters of the heat exchanger. In this work, we present a study led on an earth-to-air heat exchanger (EAHE) operated under the climatic conditions of Algeria Sahara. A dynamic modeling of the system has been presented in detail and the effect of pipe extremities has also been taken into account in this study. Results indicate that the air outlet temperature decreases with increasing of the length of buried pipe whereas it increases with increasing of the pipe section and the air velocity. However the daily mean efficiency increases when the pipe length increases but it decreases if the pipe section or the air speed increases. In addition, the effect of the pipe thickness is also studied in this work and it was found that the performances of the EAHE are weakly affected by this last parameter.