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Types and functions of shading nets in greenhouses
Summer is coming soon, and our greenhouses also ushered in the phenomenon of excessively high temperature at noon. The method we usually use is to rely on natural ventilation and opening of the sunshade. Today I will introduce to you the classification and selection criteria of our smart greenhouse shading nets, as well as their functions.
The growth of all things depends on the sun, and the increase in the temperature inside the greenhouse is also due to the solar radiation inside the sun. The primary function of the greenhouse shading net is to block the rainy light from entering the interior of the greenhouse and reduce the temperature in the greenhouse. The use of the greenhouse shading net and the fan water curtain forced air cooling system can easily achieve the effect of the temperature within 30 degrees in the north. At the same time, the greenhouse shading net is also a cooling method with low energy consumption.
1. Classification of greenhouse shading nets: According to the layout, they can be divided into two categories: tiled and folded. It can be divided into indoor and outdoor according to use, and can be divided into thermal insulation type, shading type and thermal insulation shading type according to function. According to the main materials of sunshade, it can be divided into knitted mesh and aluminum foil mesh.
2. As long as the material of aluminum foil mesh is aluminum foil strip, polyester film, FDY polyester yarn, HDPE monofilament, it has the functions of shading and cooling, heat preservation and energy saving, humidity regulation, drip prevention and natural ventilation. Now the relatively high-grade aluminum foil mesh has also added a UV layer, which plays the role of anti-pollution, effectively absorbing ultraviolet rays, and enhancing wear resistance. At present, such nets are mainly used for indoor shading and thermal insulation of energy-saving high-end greenhouses in China. The shading rate is usually between 40% and 100%, and the shrinkage rate is not more than 1%. The normal use warranty period is not less than 5 years indoors and outdoor. Not less than 3 years, usually there are five auxiliary widths of 3.2m, 3.5m, 4.3m, 4.8m and 5.3m, and the length can be produced as required.
1. The choice of greenhouse shade net
a. Shading rate: The selection of the shading rate of the greenhouse shade net must fully consider the following aspects: greenhouse type, greenhouse covering material, local climatic conditions, and greenhouse crop varieties. Especially the light requirements of crop varieties, the light compensation point and light saturation point of photosynthesis of different crops in each growth stage are different. After fully considering many factors, the most suitable light intensity for the crop should be comprehensively compared. Reasonable greenhouse shade net.
2. Cooling effect: Under the conditions of ensuring the light requirements for crop growth, the more solar radiation reflected by the greenhouse shading net, the better the cooling effect. During the cooling process of the inner shading, part of the reflected solar radiation will be absorbed by the greenhouse shading net itself, resulting in an increase in the temperature of the shading net and heat exchange with the indoor air, increasing the temperature of the greenhouse. Therefore, in order to obtain a good cooling effect in indoor cooling, the selected greenhouse shading net must have a high reflection ability to solar radiation. In general, the aluminum foil in the aluminum foil mesh has a higher reflectivity to solar radiation, and the cooling effect is much higher than that of other types of meshes. The cooling effect of the external sunshade can ignore the part of the energy absorbed by the sunshade net itself, so the cooling effect of the outdoor sunshade is generally determined by the shading rate.
3. Service life: The service life of the greenhouse shading net is related to the influence of factors inside and outside the greenhouse, among which climate conditions, temperature, ultraviolet rays and chemical substances have a great influence. Excessive temperature will lead to the degradation of the polymer in the greenhouse sunshade net, reducing the service life of the greenhouse sunshade net. The warranty period of the national standard greenhouse shade net is five years, and the actual service life is about six or seven years. The intelligence of non-standard small factories reaches about three to five years.
