glass greenhouse

Glass greenhouse is a glass as the main greenhouse, pervious to light cover material is a kind of greenhouses.  Long service life, suitable for a variety of regions and climates, to plant different plants divided into a variety of different greenhouse  

Glass greenhouse ventilation  
Glass greenhouse ventilation purpose is mainly in order to eliminate the greenhouse waste heat and greenhouse water, adjust the greenhouse air composition, eliminate harmful gases, so that the greenhouse environmental temperature, humidity and air conditions suitable for plant growth requirements.  
1 natural ventilation glass greenhouse most of the time rely on natural ventilation to adjust the indoor environment.  The structural form of large productive glass greenhouse is generally double-slope terrace greenhouse, and the ventilation form is to set ventilation Windows on the side wall and roof ridge.  The total ventilation area is not less than 15% of the greenhouse area, preferably more than 30%.  When the ridge window is opened, it is best to tilt the sash upwards more than the horizontal plane. When fully opened, it forms 100 angles with the horizontal plane, so that good ventilation can be obtained.  The ventilation volume of natural ventilation is related to wind speed, wind direction, location of ventilation window, area of ventilation window and temperature difference between inside and outside greenhouse.  When the total ventilation window area is 27% of the indoor floor area, if only the ridge ventilation, even if the outdoor wind speed reaches 10 km/h, the ideal ventilation rate of 0. 75 times per minute is not reached.  When the ridge ventilation Windows and side wall ventilation Windows are all open, the ventilation rate can reach 0.68 times/min in almost no wind, close to the normal recommended 0.75 times/min ventilation rate.  

2 forced ventilation glass greenhouse although most of the time rely on natural ventilation to adjust the environment, but in the summer temperature is higher, especially the outdoor temperature of more than 33℃ hot weather, it is difficult to meet the requirements of greenhouse cooling by natural ventilation alone, forced ventilation and with other measures to cool is commonly used in production means.  Forced ventilation is the use of fans to convert electrical energy or other mechanical energy into wind energy, forcing air flow to carry out greenhouse ventilation and achieve cooling effect.  The theoretical cooling limit of forced ventilation is that the indoor air temperature equals the outdoor air temperature.  Because, the temperature difference between inside and outside the greenhouse at this time is zero, ventilation is infinite, in practical application is impossible, due to mechanical equipment and plant physiological reasons, the general greenhouse ventilation intensity is 0.75 ~ 1.5 times per minute, can control the temperature difference between inside and outside the greenhouse within 5℃.  

3.Shading and cooling is to use opaque or low light transmittance materials to shade and reduce light, prevent excess solar radiation from entering the greenhouse, not only ensure the normal growth of crops, but also reduce the temperature of the greenhouse.  Due to the difference of shading materials and installation methods, the greenhouse temperature can be reduced by 3℃ ~ 10℃.  Shade methods include indoor shade and outdoor shade.  Indoor shading system is a support system made of metal wire or plastic wire in the greenhouse skeleton, and the shading net is installed on the supporting film line.  Generally use electric control or manual control.  Outdoor shade system is installed outside the greenhouse skeleton of a shade skeleton, the shade net is installed on the skeleton, the shade net can be used to pull the curtain mechanism or roll the film mechanism to drive, free open and close.  The outdoor installation of sunshade net has a good cooling effect, which can directly block the solar energy outside the greenhouse. All kinds of sunshade nets can be used