Developing Control Logic for a High-Pressure Fog Cooling System Operation for a Naturally Ventilated Greenhouse

Abstract

An effective control logic for a high-pressure fog cooling system for a naturally ventilated greenhouse has been developed. A suitable duration of the fog cooling system operating time is estimated using weather data and the target relative humidity inside the greenhouse with a computational model based on mass and thermal balances of the greenhouse air. The program has three main tasks: (1) to read the dry bulb temperature set point inside the greenhouse for fogging system operation and the target relative humidity defined by the user; (2) to compute a suitable duration of the fog cooling system operation; and (3) to display relevant output information to the user. The duration of fog cooling system operation decreased as the water vapor pressure deficit inside the greenhouse decreased. The control logic of the fog cooling system would be used to lower dry bulb temperature by increasing the relative humidity to the target value. Our results prove that implementing this control logic for greenhouse fog cooling system is technically feasible.