greenhouse

greenhouse

Greenhouse, also known as greenhouse, refers to a room with cold proof, heating and light transmission facilities for cultivating thermophilic plants in winter. In the season not suitable for plant growth, it can provide growth period and increase yield. It is mostly used for cultivation or seedling raising of warm vegetables, flowers, trees and other plants in low temperature season. Greenhouse is a building that can control or partially control the environment of plant growth. It is mainly used for non seasonal or non regional plant cultivation, scientific research, additive breeding and ornamental plant cultivation.

Explanation of words

Warm house.

Han huankuan's "on salt and iron: take down" says: "the clothes are light and warm, and the fur is beautiful. They are in the greenhouse, and they don't know that those who ride in the border city and float in the Hu Dynasty, and those who live in the countryside are in danger."

Chen Shidao of the Song Dynasty wrote in Volume 2 of "talking about Cong in the back mountain": "Xia Ying Gong Fu, a greenhouse for daily accounts, gives up his clothes, and all the guests laugh."

"There is a greenhouse under the building and a bed in the middle. The system is different from that of ordinary people."

2. The name of the palace.

Ban Gu's biography of Huo guangzhuan in the history of the Han Dynasty: "a nine guest greenhouse was set up in the night alone, and my elder brother-in-law Changyi guanneihou was extended."

In the Southern Dynasty Liang Xiaotong's selected works Zuo Si's Ode to the capital of Wei: "Danqing binghuan, a unique greenhouse." Liu Liangzhu: "greenhouse, the name of the hall."

Zhang Lei of the Song Dynasty wrote in the biography of Madame Zhu: "I was lucky to be in fenyin. I lived in the back soil of the ancestral temple. I helped Fenshui and drank the minister. I wrote the poem of autumn wind. I went back to Weiyang and sat in the greenhouse. Since then, my wife has been a little spoiled."

He Jingming's poem "to Zhang Jisheng:" greenhouse Millennium trees, Penglai five color clouds. "

3. Houses for cultivating thermophilic plants in winter shall be equipped with cold proof, heating and light transmission equipment.

"In winter and October, orchid and jasmine enter the greenhouse," says Zhang Chao of the Qing Dynasty

Lu Xun's "morning and evening picking up Mr. Fujino": "as soon as you arrive in Beijing, please enter the greenhouse and call it" agave. "

Basic meaning

brief introduction

In the season not suitable for plant growth, it can provide growth period and increase yield. It is mostly used for cultivation or seedling raising of warm vegetables, flowers, trees and other plants in low temperature season. There are many kinds of greenhouses. According to different roof truss materials, lighting materials, shapes and heating conditions, they can be divided into many kinds, such as glass greenhouses, plastic polycarbonate greenhouses; single span greenhouses, multi span greenhouses; single roof greenhouses, double roof greenhouses; heating greenhouses, non heating greenhouses, etc. The structure of greenhouse should be sealed and insulated, but it should be convenient for ventilation and cooling. The modern greenhouse has the equipment to control the temperature, humidity, light and other conditions, and uses the computer to automatically control to create the best environmental conditions for plants.

Greenhouse is a kind of building which uses daylighting covering materials as all or part of the envelope materials, and can be used to cultivate plants in winter or other seasons that are not suitable for the growth of open plants.

Historical origin

The origin of greenhouses can be traced back to the first emperor of Qin Dynasty. According to Wei Hong, a scholar, in the preface to the imperial edict, it is recorded that "the Qin Dynasty burned books, fearing that the world would not change the method, but all the people who were born worshipped as lang. about 700 people planted melons in the middle temperature of Lishan mausoleum valley." He lived for more than 200 years. His records must be based on the history of public praise.

Yan shigu, a scholar of Tang Dynasty, said in the annotation of Hanshu, Volume 88, biography of scholars No. 58 that "the place of wet soup in Xinfeng County is called Zhuru township". Among them, "the place of wet soup" should be what Weihong called "the place of middle temperature in Lishan Linggu", which further consolidated Weihong's credibility. Wei Hong's records about Qin Shihuang reveal a valuable agricultural technology information, that is, in the Qin Shihuang period, the Chinese people had invented the greenhouse technology.

Main categories

According to the final use function of greenhouse, it can be divided into productive greenhouse, experimental (Educational) greenhouse and commercial greenhouse. The greenhouses for vegetable cultivation, flower cultivation and breeding are all productive greenhouses; the artificial climate room and greenhouse laboratory are experimental (Educational) greenhouses; various ornamental greenhouses, retail greenhouses and commodity wholesale greenhouses are commercial greenhouses.

According to the model, the greenhouses can be divided into glp622 single span / multi span combined 6-type combined 8-type gkw7430 film gsw8432 / 8430 / 825 greenhouse and PC board greenhouse.

According to the material, greenhouse can be divided into film greenhouse, glass greenhouse and plastic plate greenhouse.

Plastic material

Large scale multi span plastic greenhouse is a kind of greenhouse type which appears and develops rapidly in recent ten years. Compared with the glass greenhouse, it has the advantages of light weight, less skeleton materials, low shading rate of structural parts, low cost and long service life. Its environmental control ability can basically reach the same level as the glass greenhouse. The user acceptance ability of plastic greenhouse is far higher than that of glass greenhouse all over the world, and it has become the mainstream of modern greenhouse development.

Structure of plastic greenhouse

1. Overall dimension of plastic greenhouse

Such greenhouses have different structural sizes in different countries. But on the whole, the span of general greenhouse is 6m ~ 12M, the bay is about 4m, and the eaves height is 3 ~ 4m. For the multi span greenhouse with natural ventilation, the maximum width of the greenhouse should be limited within 50m, preferably around 30m, when the side window and ridge window are used together; for the multi span greenhouse with mechanical ventilation, the maximum width of the greenhouse can be expanded to 60m, but preferably around 50m; for the length of the temperature chamber, it is better to limit within 100m, but not strictly The requirements of the government.

2. Main structure

The main structure of plastic greenhouse generally uses hot-dip galvanized steel pipe as the main bearing structure, factory production and on-site installation. Because of its light weight and weak resistance to wind and snow load, the overall stability of the structure should be fully considered. Generally, vertical diagonal bracing should be set in the second span or the second bay indoors, and necessary space support should also be set in the external protection structure and roof of the greenhouse. It is better to have diagonal support (diagonal tie rod) anchored to the foundation to form a spatial stress system.

The main structure of plastic greenhouse should have the ability to resist at least 8 levels of wind, and it is generally required to have the ability to resist 10 levels of wind.

The snow load bearing capacity of the main structure should be determined according to the actual snowfall conditions in the construction area and the winter use of the greenhouse. When used in the north, the design snow load should not be less than 0.35kn/m2.

For the annual operation of plastic greenhouse, many load factors such as equipment weight, plant lifting, maintenance and so on should also be considered.

Glass material

Glass greenhouse is a greenhouse with glass as transparent covering material.

design requirement

In addition to meeting the strength requirements, the foundation design should also have sufficient stability and resistance to uneven settlement. The foundation connected with the support between columns should also have sufficient function of transferring horizontal force and spatial stability. The bottom of the greenhouse should be located below the frozen soil layer, and the influence of heating on the frozen depth of the foundation can be considered according to the climate and soil conditions. Generally, the bottom of the foundation should be more than 0.5m lower than the outdoor ground, and the distance between the top of the foundation and the outdoor ground should be more than 0.1M, so as to prevent the exposure of the foundation and adverse effects on cultivation. Except for special requirements, the distance between the top of greenhouse foundation and indoor ground should be more than 0.4m.

Independent foundation. Reinforced concrete is usually used.

Strip foundation. Masonry structure (brick and stone) is usually used, and the construction is also carried out by on-site masonry. A reinforced concrete ring beam is often set on the top of the foundation to install embedded parts and increase the strength of the foundation.

The steel structure mainly includes: greenhouse load-bearing structure and the support, connector and solid parts to ensure the stability of the structure.

The design of glass greenhouse steel structure in China mainly refers to the greenhouse design codes of Holland, Japan and the United States. But in the design, we must consider the structural strength, structural rigidity, structural integrity and structural durability.

Classification: glass greenhouse can be generally divided into Wenluo type and big ridge type, the top is mostly made of tempered glass, surrounded by ordinary float glass or insulating glass, there are also glass greenhouses, the top is made of sunlight plate, surrounded by glass, etc.

performance

Transparence

Greenhouse is a daylighting building, so the transmittance is the most basic index to evaluate the transmittance of greenhouse. Transmittance refers to the percentage of the amount of light penetrating into the temperature room and the amount of light outside. The light transmittance of greenhouse is affected by the light transmittance of greenhouse covering materials and the shadow rate of greenhouse skeleton, and the light transmittance of greenhouse changes at any time with different solar radiation angles in different seasons. The light transmittance of greenhouse has become a direct factor for crop growth and selection of crop varieties. Generally, the light transmittance of multi span plastic greenhouse is 50% ~ 60%, that of glass greenhouse is 60% ~ 70%, and that of solar greenhouse is more than 70%.

Heat preservation

Heating energy consumption is the main obstacle of greenhouse operation in winter. Improving the heat preservation performance of greenhouse and reducing energy consumption are the most direct means to improve greenhouse production efficiency. The heat preservation ratio of greenhouse is a basic index to measure the heat preservation performance of greenhouse. The heat preservation ratio of greenhouse refers to the ratio of the area covered by transparent materials with low thermal resistance to the total area covered by envelope with high thermal resistance. The larger the heat preservation ratio, the better the heat preservation of greenhouse

Chinese PinYin : Wen Shi