Numerical study of earth-to-air heat exchanger for three different climates

Abstract

A numerical study was conducted for prediction the thermal behavior of an Earth-to-Air Heat Exchanger (EAHE) for three cities in México. The climate conditions correspond to an extreme heat in summer and low temperature in winter (Cd. Juárez, Chihuahua), mild weather (México city) and hot weather (Mérida, Yucatán). A Computational Fluid Dynamics code based on the Finite Volume Method has been developed in order to model the EAHE. Simulations have been conducted for sand, silt and clay soil textures for the cities of Cd. Juárez, México city and Mérida, respectively. Also, for different Reynolds numbers, Re = 100, 500, 1000, 1500 through one year. For Cd. Juárez, and México city, simulation results reveal that the thermal performance of the EAHE is better in summer than in winter, decreasing the air temperature in an average of 6.6 and 3.2 °C for summer and increasing it in 2.1 and 2.7 °C for winter, respectively. By contrast for Mérida, EAHE had its best thermal performance in winter, increasing the air temperature in 3.8 °C. It is concluded that the use of EAHEs is appropriate for heating or cooling of buildings in lands of extreme and moderate temperatures where the thermal inertia effect in soil is higher.