The temperature regulation control in glass greenhouses and other greenhouse equipment includes three aspects: heat preservation, heating and cooling. The heat preservation method appropriately lowers the height of the glass greenhouse, reduces the surface area of the protective structure, and reduces the heat dissipation area of the greenhouse, which is conducive to improving the temperature. For the selection of the masking material, the first consideration is the transparency of the masking material to solar radiant energy in daytime and the barrier to long-wave radiation at night.
In the selection of concealment methods, the thermal insulation effect of multi-layer concealment is obviously better than that of single-layer concealment. In recent years, the first generation of plastic greenhouses in the Yangtze River Basin has promoted the "three sheds and five scenes" multiple concealment insulation methods, which is the use of large sheds + middle sheds + small sheds. , Plus a layer of grass thatch or thick non-woven fabric to cover the outside of the small arch shed, so that the temperature-loving fruits and vegetables in this area can be cultivated in winter and spring, which significantly improves the utilization rate of the greenhouse and adds economy.
Heating methods Glass greenhouses and other greenhouse equipment can be heated by hot air heating, hot water heating, electric heating, radiant heating and other methods, and their heating effects, equipment costs, and operating costs are very different. The effect of hot water heating is stable, but the one-time investment is large, and it is used for heating of large-scale smart greenhouses; the one-time investment of hot air heating is only about 1/5 of that of hot water heating, but the operating cost is relatively high, and it is suitable for various types of plastics. shed.
Electric heating has higher thermal efficiency, but consumes a lot of electricity, and is mainly suitable for seedling nursery; radiant heating is a method of heating with liquefied petroleum gas burning, which consumes more gas, and is only suitable for temporary auxiliary heating. The cooling method reduces the solar radiant energy entering the greenhouse through shading. In summer, under strong sunlight conditions, shading 20% to 30% can reduce the temperature in the greenhouse by 4 to 6°C. The glass greenhouse is equipped with two sets of curtain systems inside and outside, and the cooling effect of the external sunshade is better than that of the internal sunshade.
