A method of cooling greenhouses by controlling both the rates of fog generation and forced ventilation
Continuous fog spraying reduces the variations in the temperature and humidity, thereby reducing the adverse effects of intermittent spraying. A rate-controllable fog-generation method can be used to produce continuous fog spraying. The fog-generation rate can be easily controlled by controlling the pressure of a compressor with an inverter. The ventilation rate is also an important factor for controlling fogging systems because the air cooling and evaporation rate of the fog are affected by the ventilation rate. Control of the fog-generation and ventilation rates can efficiently decrease the air temperature in a greenhouse. However, there are few studies using both a rate-controllable fog-generation method and forced ventilation. In this study, we controlled both the fog-generation rate and the rate of forced ventilation. An experimental greenhouse installed with a fog cooling system and fans was used in the experiment. The fog-generation rate and fan speed were controlled by inverters connected to each device on the basis of the environmental conditions outside and inside the greenhouse, and the target air temperature inside the greenhouse. As a result, a rate-controllable fog-generation method that controls both the fogging and ventilation rates can produce continuous fog spraying and control the air temperature inside the greenhouse with low water and energy consumption.
Ishigami, Y., Asai, T. and Goto, E. 2017. A method of cooling greenhouses by controlling both the rates of fog generation and forced ventilation. Acta Hort. (ISHS) 1170:277-282
air temperature, electric frequency, energy consumption, evaporation ratio, greenhouse environment