Multi-layer covering technology and application effect of plastic greenhouse
With the continuous expansion of the planting area of ​​protected vegetables, the level of planting is getting higher and higher. Compared with multi-layered coverage in plastic sheds, the gap in production efficiency is increasing.
The so-called multi-layer coverage refers to the use of plastic greenhouses for three, four or more layers of film coverage, so that the cultivation of vegetables, can very clearly play the early spring morning city, late winter pull effect, thereby increasing the price of vegetables ,increase income.
First, multilayer covering technology 1 outer membrane. That is, the outermost layer of plastic greenhouse film. The outer membrane of the greenhouse is generally made of 6-8-thick polyethylene non-drip membrane.
2 inner membrane. The inner membrane is covered with at least two layers. The inner membrane may be covered with a 1.5-3 thick film. The inner membrane is 20 centimeters away from the outer membrane of the greenhouse. The inner membrane is 20 centimeters away from the inner membrane. , And so on, are covered with a layer of 20 cm interval is appropriate, in case of a column in the middle if the clip can be used to clamp the film tightly, must be formed between the two inner membrane confined space, the only way to really play insulation effect.
3 small arch and mulch. When a multi-layer inner film is set above, a small shed is also set below, and the ground film is covered with a plastic film. As a number of relatively independent enclosed spaces are formed in the greenhouse to prevent the flow of cold air, a good thermal insulation effect is achieved.
Second, multi-layer covering effect is covered with a layer of film plastic greenhouse, or take multiple layers to cover the outermost layer of space temperature, due to more solid when the fixed film, so the temperature difference between the outside of the shed is not large, the outside temperature At 0 °C, only 1 °C in the shed can only play a role in preventing frost. The greenhouse covered by the second floor, which forms a closed space inside the greenhouse, can achieve an insulation effect of about 4°C. When the outside temperature reaches -2°C, the greenhouse can still reach a temperature of 1°C above zero; a greenhouse covered with three layers can be used. , that is, two confined spaces are formed inside a greenhouse, and the heat insulation effect can reach about 8°C. When the outside temperature reaches -3°C, the temperature inside the greenhouse still reaches a zero-to-zero temperature of 5°C; a greenhouse covered with four layers covers the outer membrane of the greenhouse. Two layers of intima, and then under a small arch shed, forming three confined spaces, the insulation effect can reach 13 °C, when the outside temperature reaches -5 °C, the temperature inside the small arch shed is still maintained at 8 °C above zero.
Due to the strict sealing after the use of multiple layers, it is easy to cause humidity in the greenhouse. Therefore, it is required that both mulching in advance in early spring and delaying cultivation in autumn and winter. Under normal circumstances, when there is wind outside, the difference in temperature outside the shed will increase, and when the snow is cloudy for a long time, the difference in temperature outside the shed will decrease.
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