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Wet curtain paper: how to choose the greenhouse flowers wet curtain fan system

Visits: Date:2014/11/5 14:56:09

Action principle

First of all, to understand the role of principle of fan. When the hot air is inhaled through the outdoor suction wet curtain full of water, water heat absorption and evaporation wet curtain paper on, thereby reducing the temperature of the air entering the greenhouse. Usually, by the wet, wet curtain curtain of water distribution system, the water pump and water tank is composed of "wet wall", continuously build along side wall of greenhouse, and the fan is arranged at the other side of central gable greenhouse. Wet curtain must be kept moist to ensure the evaporative cooling process is completed, according to the size of the greenhouse and the region, the selection of proper fan installed in the wet curtain wall opposite, to make the air flow smoothly through the greenhouse.

Evaporative cooling effect and air drying degree, and the wet bulb temperature of air associated with the dry bulb temperature difference. Wet and dry bulb temperature of air not only with the geographic and seasonal change, but the day has changed. Despite the change in one day dry bulb temperature could be as high as 14 degrees, but the amplitude of variation of wet bulb temperature only about dry bulb humidity 1/3. Therefore, in high humidity area at noon, evaporation system can still cooling, which is required for the production of greenhouse.

Selection principle

Selection principle of wet curtain size is should make wet curtain system to achieve the best results. Often used in flower production in greenhouse is 10 cm thick and 15 cm thick fiber wet curtain. 10 cm thick fiber wet curtain, through the wet curtain air velocity of 76 M / min operation best. 15 cm thick paper wet curtain requires air speed of 122 M / min.

The choice of the thickness of the wet curtain, in addition to considering the location, climate conditions, should also look at the temperature of indoor wet curtain and fan distance and flower crops on temperature sensitive degree. If the fan and a wet curtain the greater distance (more than 32 meters), recommend the use of 15 cm thick wet curtain; if the cultivation of flowers is more sensitive to the greenhouse temperature to high temperature tolerance ability is poor, it is recommended to use the 15 cm thick wet curtain. On the contrary, if the temperature of the indoor wet curtain and fan distance smaller or flower more sensitive to low temperature, you can use a 10 cm thick wet curtain.

Considered from the economic point of view, 10 cm thick wet curtain the price must be lower than the wet curtain thickness of 15 cm, only the price of 2/3.

In addition, the wet curtain air inlet size bigger is better. Because the air inlet size is too small to increase pressure, thereby greatly reducing the fan efficiency, increase power consumption.

The estimation method of the traditional greenhouse cooling equipment:

1 greenhouse necessary ventilation rate = length x width x 8cfm greenhouse (Note: CFM for air flow unit, cubic feet per minute), the ventilation quantity per unit floor area should be based on the altitude and light intensity adjustment.

Wet curtain area estimation needs 2. If the choice of 10 cm thick wet curtain, wet curtain area = greenhouse necessary ventilation rate / speed 250. If using a 15 cm thick wet curtain, wet curtain area = greenhouse necessary ventilation rate / speed 400. Using the calculated wet curtain area divided by the wet curtain covering the ventilation wall length, draw wet curtain height. In the humid climate area, fan air volume and wet screen size to increase 20%. In accordance with the hot air and cold air in principle in the wet curtain fan should be installed in the greenhouse above, so is the greenhouse built in early stage.

However, in recent years, the wind machine of high-end flower greenhouse wet curtain installation of continuous downward trend. Now in the greenhouse construction process, usually the blower mounted on the container height 1/3 below, 2/3 is installed in the seedbed surface above, wet curtain from 30 cm above the ground began to install, this installation is mainly based on the crop planting on the bed surface actually feel the temperature to design. Because although the greenhouse at the top of the temperature is very high, but the leaves of the plant feel, so it does not matter, there is no need to spend to reduce regional temperature plant reach the unnecessary energy consumption, while the fan is installed in the bed below, is conducive to the growth of plant roots.