Analysis of the soil domain size for simulations of ground-air heat exchangers.

Resumo

Based on the fact that climatization systems are responsible for a large portion of electricity consumption
worldwide, the present work was dedicated to analyzing the domain soil size required to simulate a Ground-Air
Heat Exchanger (GAHE): a passive air conditioning system that uses the soil as a heat exchanger, heating or
cooling buildings according to climatic conditions. In transient simulations, the computational time used for the
analysis depends directly on the size of the domain imposed on the soil. However, if the dimensions of this domain
are not adequate, large discrepancies can occur in the results obtained. To obtain the optimized dimensions of this
domain, simulations using CFD (Computational Fluid Dynamics) were performed. First, the best time step was
verified. After, the domain of soil and finally the installation depth of the exchanger were obtained, all under the
same external condition. Sinusoidal equations representing the climatic conditions of the city of Ponta Grossa -
PR were used in this study. The optimized values obtained were 8 hours of the time step, 4 m of soil domain width,
and 2.5 m of pipe depth.