In most parts of my country, the summer is hot and the temperature is relatively high. When the outdoor temperature is above 30°C, the temperature inside the greenhouse exceeds this 40°C. If only by ventilation, the temperature in the greenhouse is still above 35℃, normal production cannot be carried out in the greenhouse, and other cooling methods must be used to reduce the indoor temperature. The main greenhouse cooling methods used in daily production are
1. Shading and cooling is the use of opaque or low light transmittance materials to shade and reduce light to prevent excess solar radiation from entering the greenhouse, which not only ensures the normal growth of crops, but also reduces the temperature of the greenhouse. Due to the difference in shading materials and installation methods, the greenhouse temperature can generally be reduced by 3℃～10℃. Shading methods include indoor shading and outdoor shading. The indoor shading system is a support system made by pulling metal wires or plastic netting wires on the greenhouse framework, and installing the shading net on the supporting film line. Generally adopt electric control or manual control. The outdoor shading system is to install a shading framework outside the greenhouse framework, and install the shading net on the framework. The shading net can be driven by a curtain pulling mechanism or a film rolling mechanism, and it can be opened and closed freely. The sunshade net is installed outdoors and has a good cooling effect. It can directly block the solar energy outside the greenhouse. Various types of sunshade nets can be used.
2. Evaporative cooling: Evaporative cooling uses the unsaturation of air and the latent heat of evaporation of water to cool down. When the moisture in the air is not saturated, the moisture will evaporate and become water vapor into the air. While the water evaporates, it absorbs the heat in the air, reduces the air temperature and increases the air humidity. In the process of evaporative cooling, the air flow inside and outside the greenhouse must be ensured, the high temperature and high humidity in the greenhouse must be discharged out of the greenhouse, and fresh air must be added, so forced ventilation must be adopted. At present, the method of cooling by evaporation is wet curtain-fan cooling and spray cooling.
3. Roof spray cooling system is to spray water evenly on the roof of the glass greenhouse to reduce the temperature of the greenhouse. When water flows on the roof of the glass greenhouse, the water exchanges heat with the glass of the greenhouse roof to take away the heat in the greenhouse. In addition, when the thickness of the water film is greater than 0.2 mm, all the energy of solar radiation is absorbed and carried by the water film. Go, this point is equivalent to shade.
indoor greenhouse glass