Temperature and Relative Humidity Control in a Greenhouse Evaporative Cooling-pad system
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Abstract
This research aimed to study the control of temperature and relative humidity of the air inside a greenhouse equipped with an evaporative cooling pad system. The control system was divided into 3 systems: The temperature control system at 25°C, the relative humidity control system at 70% RH, and the vapor pressure deficit (VPD) control system at 0.85 kPa. It was found that on a cool day, the temperature control system can maintain an average temperature of about 25°C. However, on a hot day, the system cannot effectively control or reduce the average temperature inside the greenhouse to the required value. Nonetheless, it can successfully control the average temperature inside the greenhouse to be about 5-7°C lower than outside the greenhouse. The relative humidity control system maintained the average relative humidity inside the greenhouse at about 70% RH every day of the test, but the average temperature inside the greenhouse was about 28-35°C. The VPD control system can be maintained at the specified value for some time; it varies according to the temperature and relative humidity of the air. However, the average temperature and relative humidity inside the greenhouse were still within the suitable range for growing plants in the greenhouse. The water and electricity consumption of the system depends mainly on the weather conditions and the operation of the control system. The relative humidity control system consumes the lowest electrical consumption, while the temperature control system has the highest electrical consumption, Therefore, the temperature control system has the highest cost compared with the relative humidity control system and the vapor pressure deficit control system.
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ลิขสิทธ์ ของมหาวิทยาลัยเทคโนโลยีราชมงคลพระนครReferences
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