Numerical analysis of the influence of operational and constructive parameters on the operation of earth-air heat exchangers

Abstract

The search for thermal comfort elevates the electric energy consumption, due the need of climatization to reach a pleasurable temperature: cooling at summer and heating at winter. Looking for the reduction of electric energy consumption by air conditioners, we reach the earth-air heat exchanger (EAHE), that uses the incident solar radiation over the surface of the soil as a source of clean and renewable energy. That way the flowing air of EAHE is directed toward edifications, providing a significant improvement of the thermal condition. This is possible due to the thermal inertia of the soil, which has milder temperatures compared to the air’s temperature. Thus, the goal of this study is numerically evaluate the influence of the air’s flow velocity in the duct and the spacing between the parallel ducts on the thermal performance of the TCSA. For that a computational model, verified and validated, developed in the software FLUENT, which is based on the finite volume method (MVF), was employed. The results show that during the hottest periods the lowest flow velocity imposes in a better thermal performance of the TCSA. It was also observed that after 1 m of spacing between ducts the thermal exchange between each duct and soil is not significantly affected.