Experimental and numerical analysis of an earth–air heat exchanger

The need to develop new technologies that allow the use of sustainable alternative sources of energy is increasingly evident. Thus, this work presents an experimental and numerical study of earth–air heat exchangers, which are used to reduce consumption of conventional energy for heating and cooling of built environments through the use of thermal energy contained in the soil. The experiment was conducted in southern Brazil in the city of Viamão, and its results were used to validate the computational modeling of heat exchangers. In the present work, the variation of air temperature inside the ducts, to an annual cycle, was investigated. The numerical solution of the conservation equations of the problem is performed with a commercial code (FLUENT) which is based on the Finite Volume Method (FVM). Turbulence is tackled with the Reynolds Stress Model (RSM). The transient temperature fields predicted numerically was compared with the experimental ones, the highest difference found was lower than 15%. The results showed the validity and effectiveness of the employed computational model, enabling its use for future researches and projects developments about earth–air heat exchangers.

► Experimental and numerical studies for sustainable alternative sources of energy. ► Earth–air heat exchangers used for heating and cooling of built environments. ► Potential for heating the air that circulates in buried ducts higher than 8 °C. ► Potential for cooling can reach to approximately 4 °C. ► The experimental and numerical results had good agreement.