The southern provinces of Guangxi, Guangdong, Fujian and other provinces belong to the southern subtropical climate zone, with hot and humid seasons, especially from June to September. The monthly average maximum temperature is above 30 °C, and the average relative humidity is over 80%. In the meantime, due to the greenhouse effect The indoor temperature is as high as 40 ° C -45 ° C, 10 cm below the roof, the temperature can reach up to 60 ° C. The relative humidity is over 90%. The normal temperature of vegetables is 23°C-30°C (short-term can withstand 35°C-40°C high temperature), and the suitable humidity is 50%-80%. Such high temperature and humidity are extremely strong for vegetable growth. Unfavorable, leading to serious occurrence of a variety of vegetable diseases, and some even lost. For the southern region, greenhouse ventilation and cooling work is more important than thermal insulation. Practice has proved that as long as the greenhouse design is reasonable, ventilation and cooling measures are appropriate, even in the most sultry July and August at noon, the temperature in the greenhouse can also be The control is between 28 ° C and 32 ° C, and the relative humidity is controlled at about 80%. Now combined with the work and design of my design and construction in recent years, I will talk about some technical problems of greenhouse ventilation and cooling in the south. 1 The choice of greenhouse type ventilation and cooling are closely related, the better the ventilation effect, the stronger the cooling and dehumidification capacity. Ventilation is available in both natural and forced ventilation. Most of the greenhouse relies on natural ventilation to regulate the indoor environment. The indoor temperature of the natural ventilation is basically controlled to be only 3-5 °C higher than the outdoor temperature. Therefore, it is necessary for the southern greenhouse to have a simple and effective natural ventilation system. The structure and type of the greenhouse directly affect the natural ventilation effect. When selecting materials during construction, the following two factors should be considered.
The size of the greenhouse is generally small, the size of a simple plastic greenhouse is small (about 180 square meters per shed), and it is narrow and rectangular. The film of the rubber injection molding machine on both sides is well ventilated. The greenhouses generally have an area of ​​2000-5000 square meters, and an area that is too large is not conducive to summer cooling. The maximum width of a naturally ventilated townhouse greenhouse is generally less than 50 meters, preferably about 30 meters. If forced ventilation is provided, the maximum width can be extended to 60 meters and the length is not strictly required. It is best not to exceed 100 meters. The universal joint greenhouse has a span of 6-12 meters per arch, a 4m opening, and a shoulder height (sink height) of 3-4 meters. It is more suitable, with good effect, low material and low cost.
Greenhouse roofing and window-opening greenhouses can be divided into three types according to the roof shape: arch dome, zigzag and roof window. Most of the single plastic greenhouses are arched dome greenhouses, while the multi-span greenhouses have more forms, with arch domes as well. The zigzag and roof window greenhouses are fixed vertical vertical windows. The hot air always moves upwards, and the external wind pressure on the roof is also large. If combined with the side wall ventilation, the hot pressure ventilation height difference is not large. Therefore, under the same window opening area, the roof window has better ventilation capacity than other ventilation windows. On one side of the greenhouse, the ventilation effect is greatly affected by the wind direction; the dome-shaped greenhouse with the top window is basically unaffected, and the window opening area can be made very large (accounting for 40%-50% of the roof area). In the windless state, the ventilation cooling capacity is much stronger than the other two. This kind of greenhouse has reasonable force, less material, simple manufacturing, smooth lines, small wind resistance and strong weather resistance. It does not produce the top heat accumulation (saw-shaped greenhouse shadow area) like the zigzag greenhouse.
Wood Sander / Sanding Machine is used for
Cabinet doors, sliding doors, structural section, soorframe,
wood doors, baseboard, photo frame, window-blinds
Wood, MDF, Blockboard, multilayer
Main configuration:
four sets of sand disc swing sanding + two sets of horizontal sand swing sanding + two sets of twill rollers
Structured frame, stable and firm
Hangzhou Xiaoshan reducer Taizhou summer motor
Delta inverter
Chuangwei stepper motor and driver
Xinjie touch screen operation
PLC control system
Imported sisal
Original imported PEK slider
Rail slider automatic lubrication
Heavy conveyor belt
Each set of sand rollers is independently lifted and lowered.
Sand roller and sand disc are pulled independently. It is convenient to change sandpaper.
Door Sander Machine,Wood Sander Machine,Cabinet Sanding Machine,Wooden Door Sander Machine
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