Computational modeling of an earth-air heat exchanger using different modeling for turbulence

Abstract

Solar radiation is a source of renewable energy and its thermal energy can be exploited by using earth-air heat exchanger (EAHE) in built environments, could be an alternative to reduce electricity consumption. These devices consist of ducts buried in the soil, where the ambient air flow occurs. The air is cooled/heated by the soil in hot/cold periods can be used for cooling/heating of built environments. To numerically simulate the thermal and fluid dynamic behavior of an EAHE is necessary to use some modeling for turbulence. Thus, this work aims to study different turbulence modeling for approach of numerical approach of turbulence into URANS framework: RSM (Reynolds Stress Model), k-ε standard, k-ω standard and Spalart Allmaras in the study of the main operational principle of an EAHE with a straight duct, in order to propose a recommendation about the most suitable models for this kind of application. The computational modeling was performed using the FLUENT software which is based on the finite volume method (FVM). The numerical results obtained with URANS models were in agreement with those depicted previously in literature. Furthermore, the Spalart Allmaras and k - ω standard models led to a reduction of almost 40 % in time processing when compared with RSM, being that models recommended for this kind of application in EAHE.