Development of Simplified Numerical Model for Evaluation of the Influence of Soil-Air Heat Exchanger Installation Depth over Its Thermal Potential

The main purpose of the present study is the numerical investigation of the influence of installation depth over the thermal potential of a soil-air heat exchanger for a clay soil of southern of Brazil. The problem is based on the numerical solution of conservation equations of mass, momentum and energy for a three-dimensional simplified domain. The equations are solved with the finite volume method (FVM). The turbulent flow in the duct of the device is tackled with the Reynolds Stress Model (RSM). The transient temperature fields predicted by the simplified numerical model were compared with numerical and experimental results of literature. The highest difference between the present results and the experimental predictions was nearly 11%. The results for several profundities showed that the installation depth of the buried duct has a significantly influence over the thermal potential of soil-air heat exchanger. It was also observed the augmentation and reduction of the air temperature, for a duct buried at a depth of 3m, in comparison with the external environment temperature of nearly 17% (3°C) and 25% (8°C) for two typical days of winter and summer, respectively.