A numerical study on heating performance of horizontal and vertical earth-air heat exchangers with equal pipe lengths

In this study, heating performances of horizontal and vertical earth-air heat exchangers with equal pipe lengths were evaluated in ANSYS FLUENT 19.2 simulation program based on CFD for the winter period of Bitlis, Turkey. Thermal per­formance analyses regarding vertical and horizontal 3-D-modeled earth-air heat exchangers were evaluated in steady-state condition of the simulation program for different values of Re = 5⋅103, 104, 2⋅104, 4⋅104, 6⋅104, 8⋅104, and 105 numbers by using standard k-ε turbulence model. Numerical results obtained from CFD based simulation program were compared with a numerical study in the literature, and it was determined that there was a consistency between the results. The pressure loss and fan power values of horizontal and vertical earth-air heat exchangers were also investigated in addition their thermal performances. A good agreement was found between the pressure loss values obtained from the theoretical and simulation calculations of both earth-air heat exchangers. Considering the temperature increases in both earth-air heat exchangers, the highest and lowest temperature increases were observed in vertical earth-air heat exchanger with 22.52 K and 10.67 K, respectively. The best thermal performance was observed in vertical earth-air heat exchanger for 5⋅103, 104, and 2⋅104 values of Reynolds number and in horizontal earth-air heat exchanger for 4⋅104, 6⋅104, 8⋅104, and 105 values of Reynolds number