Glass greenhouse ventilation
Glass greenhouse ventilation purpose is mainly to eliminate the waste heat and the moisture inside the greenhouse of greenhouse to adjust air composition in greenhouse, eliminate harmful gas, make the environment temperature, humidity and air inside the greenhouse condition such as suitable for plant growth.
1. Natural ventilation glass greenhouse relies on natural ventilation to regulate indoor environment most of the time.The structure of large producer glass glasshouse is generally a double slope surface connecting house greenhouse, ventilated form for the side wall and the roof of the ventilation window.The total ventilation area is not less than 15% of the greenhouse area, preferably more than 30%.When the roof of the roof of the roof opens, the window fan is better than the horizontal plane, when the full opening and the water plane form 100 angles, the good ventilation effect can be obtained.The ventilation volume of natural ventilation is related to wind speed, wind direction, ventilation window position, ventilation window area and temperature difference of greenhouse.When the total area of the ventilation window is 27% of the indoor area, if only the roof of the roof is ventilated, even if the outdoor wind speed is up to 10km/h, it can not reach the ideal gas exchange rate of 0.75 times per minute;When the roof ventilation window and side wall ventilating window are fully opened, the ventilation rate can reach 0.68 times/min in almost no wind, close to the normal recommended 0.75 / minute ventilation rate.
2. Although forced ventilation glass greenhouse rely on natural ventilation to regulate the environment most of the time, but in summer the temperature is high, especially outdoor temperature more than 33 ℃ hot weather, natural ventilation alone is difficult to meet the requirements of greenhouse cooling, the use of forced ventilation and in combination with other measures to cool is commonly used in the production.Forced ventilation is used to convert electrical energy or other mechanical energy into wind power, forcing air flow to make the greenhouse gas and cooling effect.The theoretical cooling limit for forced ventilation is that indoor air temperature is equal to outdoor air temperature.Because, at this time of the greenhouse inside and outside temperature difference is zero, ventilation rate for infinity, in the actual application is impossible, because of mechanical equipment and plant physiology, general strength of greenhouse ventilation ventilation per minute 0.75 ~ 1. 5 times, can control the temperature difference between inside and outside greenhouse within 5 ℃.
