Design reference factors for ventilation system of multi-span greenhouse
Multi span film greenhouse is a kind of large greenhouse, its individual area can reach several hectares, so many people will pay attention to the temperature problem in the greenhouse, and how to design the greenhouse ventilation. So today I want to share with you the design reference factors for large multi-span film greenhouse ventilation systems.
1. The design of ventilation system should meet the needs of greenhouse crop temperature and humidity and carbon dioxide concentration control.
2. The larger capacity of the ventilation system design should be maintained under unfavorable external conditions during the proposed service period, and the indoor temperature, humidity and carbon dioxide concentration meet the requirements of suitable environmental conditions for crop growth.
3. The design of the ventilation system should consider the characteristics of the external environment in different seasons, showing the requirements of temperature, humidity and carbon dioxide concentration for the multi-storey greenhouse in different seasons. The design requirements of ventilation systems in different seasons should adopt one or more indicators. Winter should consider changing the closed film greenhouse caused by high humidity, low carbon dioxide and high concentration of harmful gases indoor environment. In summer, changing the indoor high temperature caused by the greenhouse should be considered, and other cooling measures should be taken.
4. Natural ventilation should be a better choice for greenhouse ventilation. When the natural ventilation system cannot meet the design requirements of the greenhouse, the fan ventilation system should be set up.
5. When the fan ventilation in summer cannot meet the requirements of crop growth temperature, other cooling measures should be taken at the same time.
6. When the ventilation volume is greater than 0.02m/ (5S+m2), other methods should not be used to supplement CO2.
7. In order to make the indoor temperature, humidity, CO concentration distribution uniform, indoor air flow rate conducive to crop growth, indoor should be installed some circulating fans.
8. Ventilation system design should be based on the geographical location of the greenhouse, climate type, structural type and use, determine the type, size, location of the ventilation hole and the type, number and arrangement of the fan.
9. The design scheme of the ventilation system should be determined by technical and economic comparison according to the use, scale, use characteristics, outdoor meteorological conditions and crop parameter requirements of the multi-span film greenhouse.
