Abstract
Evaporative cooling systems are the currently used technology for providing cooling to greenhouses in arid regions where typically the greenhouse is ventilated. However, they consume a large quantity of water to cool the air. A closed greenhouse is proposed that uses earth-air heat exchangers (EAHE) and fogging to control the interior temperature and relative humidity in a water-efficient manner. A numerical model has been developed for the greenhouse and EAHE, and have been validated against experimental data collected from literature. Simulations are performed to compare the proposed closed greenhouse performance against the fan-pad system in a ventilated greenhouse in maintaining a suitable temperature and humidity, and to estimate the water usages. The EAHE reduced the water consumed by the fogging system by 50 % and the maximum interior temperature from 50 °C to 35 °C. The temperature reduction was found comparable to a fan-pad system with a ventilation rate of 20 air changes per hour, however, with a more stable relative humidity at approximately 75 %. Furthermore, water used for cooling was lower by one tenth of that of the fan-pad system, reducing it from 53 litre/day to 5 litre/day.
•Use of a closed greenhouse to limit water loss is studied.•Model of a closed greenhouse in an arid environment is presented.•Comparison of different cooling strategies was conducted.•Water usage and cooling effectiveness of various cooling strategies are analysed.•EAHE is promising for greenhouse temperature regulation and minimization of water usage.