Performance enhancement of earth air tunnel heat exchanger using evaporative cooling

Abstract

A thermal model has been developed to investigate the potential of using the storage capacity of the ground for cooling with the help of an earth to air heat exchanger (EAHE) system integrated with evaporative cooler. Parametric studies performed for the EAHE coupled with the evaporative cooler illustrate the effects of buried pipe length, pipe diameter, volumetric flow rate of air, number of pipes and surface-to-volume (S/V) ratio on the outlet temperature of the EAHE. An analytical solution has been derived by considering the fundamental equation of energy, heat transfer and psychrometry, for predicting the temperature at the outlet of EAHE. The results of the EAHE coupled with evaporative cooling are compared with that of EAHE without evaporative cooling for different S/V ratio and bypass factor. It is observed that the length of the EAHE pipe is reduced significantly as much as 93.5% for obtaining desired temperature at the outlet of the EAHE by the integration of evaporative cooling with EAHE. Reduction in the length of buried pipe is also noted with decrease in bypass factor of evaporator cooler. © The Author 2009. Published by Oxford University Press.