1. In summer, late spring and early autumn, due to the strong solar irradiance and the greenhouse effect, the temperature in the greenhouse during the day is often as high as 40°C, which is much higher than the optimum temperature for plant survival. In order to create and maintain an environmental temperature suitable for crop needs in the facility, it is necessary to take cooling measures. No matter what measures are taken, it is necessary to grasp or calculate the air exchange rate and air exchange rate of the facility.
2. The use of mechanical forced cooling is to use fans, cooling negative pressure fans, air coolers, air-conditioning fans, etc. to reduce the temperature. The purchase of fan equipment can be designed according to the cooling range. If the cooling conditions are strict, a powerful fan can be used. The low pressure and high flow of high-quality cooling fan equipment can be used without noise.
When natural ventilation in the greenhouse cannot meet the requirements of crop cultivation, forced ventilation can be used to cool down. Usually, this method is to open the windows on the north side for 1:3 cold wind, and install a fan on the south side to draw air out to cool the large amount of cold air in the room. The design of forced ventilation is mainly to determine the opening area and the window area of the ventilation window. Select the ventilation volume of the fan under the design pressure. Generally, the area of the designed air intake window is equal to 3-4 times of the outlet area of the fan, and the ventilation volume of the fan is selected to be slightly larger than the designed ventilation volume.
3, heat exchange cooling, the heat originally needed to be removed by various cooling measures, but it can be temporarily stored in water through the air-water heat exchange method, and the temperature drops at the same time. When the temperature in the greenhouse is too low in the evening after sunset or at night, the heat will be returned to the greenhouse through the water-air heat exchange.
4. The water curtain wet curtain fan cools down, especially used in the greenhouse flower planting, when the outside temperature exceeds 35. For E, they require room temperature to be lower than 28°C. In this case, neither natural nor forced ventilation can meet the requirements. At this time, water curtain and fan facilities should be used to cool down.
Install a fan in a well-sealed shed, and install a water curtain (that is, a wet curtain) on the other side (opposite side). In order to keep the water curtain always in a wet state, the water curtain is continuously supplied with water by a circulating pool, a water pump and a circulating pipe.
