Modeling and Experimental Study for Winter Performance of an Earth to Air Heat Exchanger: An Alternative Energy Source for Greenhouse

M. K. Ghosal, S. Nayak, G. N. Tiwari


A complete numerical model has been developed to investigate the potential of using the stored
thermal energy of ground for space heating with the help of an earth to air heat exchanger
(EAHE) system integrated with the greenhouse located in the premises of IIT, Delhi, India. The
analysis was based on quasi-steady state condition. Experiments were conducted extensively
during winter period from November 2002 to March 2003, but the model, developed, was
validated against the clear and sunny days. The performance of the system was evaluated in
terms of total heating potential obtained from EAHE, coefficient of performance (COP) and
thermal load leveling. The heating potential of the system has also been standardized by the
characteristic curve for greenhouse similar to that of flat plate collector. Temperatures of
greenhouse air were found to be on an average 7-8 0C more than the same greenhouse when
operating without earth air heat exchanger. The temperature fluctuations of greenhouse air were
also less when operated with EAHE as compared to without EAHE. Predicted and measured
values of greenhouse air temperature in the model developed, exhibited fair agreement.

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