Research On Temperature Differential Ventilation System Of Greenhouse

More and more solar greenhouses exist in northern China, gradually becoming an important part of modern agriculture. The ventilation of solar greenhouse is an important part of its production and management, which is also the main means of environmental regulation in solar greenhouse. Ventilation not only can effectively control the temperature and humidity of the air, but also can increase the flow of air in the Sunlight greenhouse, increasing the concentration of carbon dioxide and photosynthesis and the yield of crop. At present, the ventilation mechanization level of sunlight greenhouse is low in our country. People often have to climb to the top of the greenhouse vents to control the switch, which is timeconsuming and laborious. Even if there is ventilation equipment in some areas, but the automation level is low, most of which also are of manual operation or blind mechanical operation, causing unreasonable ventilation time and unscientific ventilation affecting the production of crop. In view of the present situation and on the basis of drawing lessons from domestic and foreign research, this paper designs the temperature differential Sunlight greenhouse ventilation system, accomplishing the full automatic intelligent ventilation in Sunlight Greenhouse. The main research work and innovations are as follows:(1) Determined the overall scheme of differential sunlight greenhouse ventilation system. The system is mainly composed of mechanical part, detection and analysis part and control execution part. The mechanical part includes power system design, drive system design, execution system design and fixed frame design; The detection and analysis part includes the acquisition system design, differential analysis system design and the simulation debugging; The control execution section includes field control execution section and remote control execution section, and the field control execution section mainly includes communication system design, man-machine interactive system design, drive system design, overload protection system design and manual control system design, The remote control execution section mainly includes formulation of communication protocol, wireless transmission design and overall debugging of remote control system.(2) The mechanical part of the temperature differential sunlight greenhouse ventilation system was designed. The theoretical calculation and analysis of power system, transmission system and executive system are carried out. Using SolidWorks to assembly interference check between parts and using AutoCAD to draw the mechanical part of the system drawings and to make the prototype production..(3) A new type of detachable greenhouse ventilation volume rod fixing bracket was designed. The coiled rod of ventilation system in sunlight greenhouse can be fixed on the bearing column of the sunlight greenhouse to avoid the destruction of the bearing support. At last, the mechanical strength of the rolling rod and the fixing frame was checked.(4) A temperature differential type ventilation control method for solar greenhouse was proposed. Based on the calculation and analysis of the necessary ventilation rate and the internal temperature of greenhouse, the control system also can detect greenhouse environment. Then through differential analysis, it can calculate the optimal size of air vents.(5) The remote control execution part of the ventilation system in solar greenhouse was developed. The user can realize remote monitoring, data analysis and fault diagnosis function through the remote control server, and the user can monitor the change of greenhouse environmental and to control greenhouse vents opening and closing through the mobile client anywhere.The results showed that the temperature differential ventilation system of greenhouse can accurately control the temperature in the range of set value, speed up the warming process in the morning in the sunlight greenhouse, and slow down the cooling process in the afternoon. The night temperature can increase 2~4 degrees Celsius. The system can automatically adjust the size of the vents according to the difference of environment temperature between outdoor and indoor, so it can reduce temperature change and reduce the sudden temperature or decline phenomenon caused by the vents opening and closing.