Simulation of a convectively-cooled unventilated greenhouse

Abstract

A simulation is presented to evaluate a novel cooling system for an unventilated greenhouse. The greenhouse is cooled during the day by transferring heat in the greenhouse air into a reservoir of water using an unpressurized droplet system. During the night and morning the accumulated reservoir heat is discharged to the outside air through an air-to-air heat exchanger comprised of a bank of thin-walled plastic tubes. Experiments have informed the simulation on the heat and mass transfer to falling droplets and on the heat transfer through a plastic tube with a wall thickness of 0.3 mm. If the minimum ambient temperature is 12 °C, the simulation predicts that the energy requirement of the cooling system to discharge the accumulated heat in the reservoir is 6.9 times less than the energy required for an air-cooled chiller with a coefficient of performance of 4.