Thermal heating of controlled environment greenhouse: a transient analysis

In this paper, an attempt has been made to maintain the plant and room air temperature of a controlled environment greenhouse by using a thermal storage north wall and an integration of a ground air collector. An analytical expression for the plant and room air temperature, based on energy balances for each component, have been derived in terms of climatic as well as design parameters. Numerical computation have been performed for a typical cold day of Delhi, for various temperatures and thermal load levelling. It has been observed that: (i) there is a significant effect of the thermal storage north wall and the ground air collector on the plant and room air temperatures and (ii) thermal load levelling decreases with the increase of the isothermal mass in the case of heating and vice versa for cooling, as per expectations. Experimental validation has also been done for a similar type of greenhouse with movable insulation. (C) 1999 Elsevier Science Ltd. All rights reserved.