Validation of CFD model for simulation of multi-pipe earth-to-air heat exchangers (EAHEs) flow performance

In this paper the experimentally obtained flow characteristics of multi-pipe earth-to-air heat exchangers (EAHEs) were used to validate the EAHE flow performance numerical model prepared by means of CFD software Ansys Fluent. The cut-cell meshing and the k-e realizable turbulence model with default coefficients values and enhanced wall treatment were used. The total pressure losses and airflow in each pipe of multi-pipe exchangers was investigated both experimentally and numerically. The results show that airflow in each pipe of the multi-pipe EAHE structures is not equal. The validated numerical model can be used for a proper designing of multi-pipe EAHEs from the point of view of the flow characteristics. The influence of EAHEs geometrical parameters on the total pressure losses and airflow division between the exchanger pipes can also be analyzed. Usage of CFD for a designing process of EAHEs can be helpful for HVAC engineers (Heating Ventilation and Air Conditioning). It can also be helpful for optimizing the geometrical structure of multi-pipe EAHEs in order to save the energy and decrease operational costs of low-energy buildings.