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Advantages of agricultural plastic film greenhouse


2020-08-21


Hydroponics agricultural plastic film greenhouse is a common form of the greenhouse. Why do many people choose to use this type of greenhouse? What are the advantages of plastic greenhouses? Let me introduce it to you.

Advantages of agricultural plastic film greenhouse

Hydroponics agricultural plastic film greenhouse has thermal insulation properties. After covering the film, the turbidity in the greenhouse will increase with the increase of outside temperature, and decrease with the decrease of the outside temperature. And there are obvious seasonal changes and large temperature differences between day and night. The lower the temperature, the greater the temperature difference. Generally, the daily temperature increase in the greenhouse in the cold season can reach 3-6°C, and the temperature increase ability is only 1-2°C on cloudy days or night. In the warm spring season, the temperature difference between the shed and the open field gradually increases, and the temperature increase can reach 6-15 ℃. When the outside temperature rises, the temperature of the meat in the shed will increase, and the maximum temperature can be above 20℃. Therefore, there are high temperatures and freezing hazards in the shed, which requires manual adjustment. In the high-temperature season, the shed can produce a high temperature above 50℃. Ventilate the whole shed. Cover the outside of the shed with a straw curtain or build a “pergola”, which can be 1-2℃ lower than the open-air temperature. In the winter on a sunny day, the lowest temperature at night can be 1-3°C higher than that of the open field, and on a cloudy day, several branches are the same as the open field. Therefore, the main production seasons for greenhouses are spring, summer, and autumn. Through heat preservation and ventilation, the temperature of the shed can be kept at 15-30℃.

Hydroponics agricultural plastic film greenhouse, the light transmittance of the new plastic film can reach 80-90%, but during use, the light transmittance is reduced by 10-30% due to dust pollution, adsorption of water droplets, and film aging. The lighting conditions in the greenhouse are greatly different due to the season, weather conditions, covering methods (shed-shaped structure, orientation, scale, etc.), the types of films, and the degree of use of new and old. The higher the greenhouse, the greater the difference in radiant illuminance in the vertical direction in the shed, and the irradiance difference between the upper layer and the ground in the shed can reach 20-30%. In winter and spring, the east-west extended greenhouses have better lighting conditions, which are better than the north-south greenhouses, and the local lighting conditions are almost the same. However, the irradiance on the north and south sides of the extended greenhouse can be as much as 10-20%. Different shed structures have a great influence on the light inside the shed. Although the double-layer film cover has better thermal insulation performance, the light-receiving conditions can be reduced by about half compared with the single-layer film cover.

In addition, the hydroponics agricultural plastic film greenhouse and the use of different construction materials also have a great impact on light exposure. The single steel and hard plastic structure of the greenhouse receive better light, and only reduces the light transmittance by 28% compared to the open field. The multi-span shed receives poor light conditions. Therefore, when the materials used in the construction of the shed can withstand a certain load, light materials should be selected as much as possible and the structure should be simplified, which can not affect the light reception, but also protects and is strong, economical and practical. The amount of light received by different shed structures The type of shed light transmittance Lux (10,000) light transmittance (%) Single steel structure, single bamboo and wood structure, single rigid plastic structure, multi-span reinforced concrete open-field control 7.67 6.65 7.65 5.99 10.6472.0 62 .5 71.9 56.3 100 The light transmittance of the film will be greatly reduced due to dust pollution during the coverage period. After using the new film for two days, dust pollution can reduce the light transmittance by 14.5%. It will be reduced by 25% after 10 days, and by less than 28% after half a month.

Under normal circumstances, the light transmittance can be reduced by 10-20% due to dust contamination. When severely polluted, the amount of light received in the shed is only 7%, which makes it unusable. Generally, the film is easy to absorb water vapor and condenses into water droplets on the film, which reduces the light transmittance of the film by 10-30%. Therefore, preventing film contamination and preventing condensation of water droplets are important measures. Furthermore, during the use of the film, due to high temperature, low temperature, and the influence of sunlight and ultraviolet rays, the film “ages”. The light transmittance of the film decreases by 20-40% after aging, and even loses its use-value. Therefore, the film covered by the greenhouse should be a long-life film that is temperature-resistant, anti-aging, dust-free, and drip-free, so as to enhance the light reception in the greenhouse, increase the temperature, and extend the service life.