Thermal performance simulations of Earth-Air Heat Exchangers for different soils of a coastal city using in-situ data

Abstract

Earth-Air Heat Exchangers (EAHE) work blowing the air through buried ducts to employ the soil as a heat/cold sink. Thus the thermal energy contained in the soil can meet heating/cooling needs of buildings and reduce the conventional consumption of energy. In Brazil, recent research about these devices has been done considering its south region where a subtropical climate prevails. However, there is a lack of studies addressing the thermal performance of EAHE in coastal cities, where one can find the soil very sandy and the water table near the ground surface. In particular, this paper studies numerically the installation of EAHE in three different places located in the coastal south Brazilian city of Rio Grande, where the geotechnical profiles of the soil were obtained in-situ through standard penetration tests (SPT), aiming to promote thermal performance analysis for EAHE. In the simulations presented here, the influence of the water in the soil and a shortage of clayey layers in some sites relatively reduced their performance in more than 60%. Moreover, for these sites, the thermal potential for EAHE is poorly affected by placing the ducts at depths below 2.0 m.