The basic introduction of solar greenhouse, the performance characteristics of solar greenhouse

Solar greenhouse is a relatively simple facility, making full use of solar energy, and generally does not heat up for overwintering vegetable cultivation in cold areas, while the cultivation facility for producing fresh vegetables has distinctive Chinese characteristics. It is a facility unique to our country. The structure of solar greenhouses varies from place to place, and there are many ways to classify them.

According to the wall material, it is mainly divided into dry soil greenhouse, masonry structure greenhouse, composite structure greenhouse, etc. According to the length of the rear roof, there are long back slope greenhouses and short back slope greenhouses; According to the form of the front roof, there are two-fold type, three-fold type, arch round type, micro arch type, etc. According to the structure, there are bamboo and wood structure, steel and wood structure, reinforced concrete structure, all-steel structure, all-reinforced concrete structure, suspension structure, hot-dip galvanized steel pipe assembly structure.

The front slope is covered with thermal insulation at night, and the east, west and north sides are the single-slope plastic greenhouses with enclosure walls, collectively known as solar greenhouses. Its prototype is a single-slope glass greenhouse, and the front slope light-transmitting covering material is replaced by plastic film instead of glass, which evolved into an early solar greenhouse. Solar greenhouses are characterized by good thermal insulation, low investment and energy saving, which are very suitable for use in China's economically underdeveloped rural areas.

The performance characteristics of the solar greenhouse, the lighting characteristics of the solar greenhouse are related to the season, time, weather, greenhouse orientation, structure, building materials, management technology and other natural factors. And it changes with the change of the above factors. The seasonal and diurnal trends of light intensity in the solar greenhouse are basically the same as those in the outdoor area, but the visible light is significantly weakened after the visible light enters the solar greenhouse through the plastic film, which is mainly due to the loss caused by light reflection, plastic film absorption, skeleton shading, aging of plastic film materials, dust pollution and water droplet reflection.

The middle of the greenhouse is the area with the best sunlight throughout the day. Due to the shading effect of the gables, two active low-light zones are formed at the east and west ends before noon and afternoon, which contract or expand with the change in the height of the sun and disappear at noon. In the vertical direction, the light intensity decreases from top to bottom.

In the north-south direction, the light intensity gradually weakened from south to north, and the ** pillar on the north side weakened significantly. Due to the need for heat preservation in winter and spring, the solar greenhouse is covered with straw and insulation, uncovered after sunrise and covered before sunset, artificially extending the indoor dark time. Generally, from December to February of the following year, the indoor light time is only 6-8h

After March, as the temperature rises, the covering and heat preservation time can be appropriately shortened, and the indoor light time can reach 8-loh. The spectral composition of the light chamber is related not only to the height of the sun, but also to the properties of the covering material. The ultraviolet transmittance of plastic film is relatively high, which is conducive to the robust growth of plants and promotes the synthesis of anthocyanins and VE.

The ultraviolet transmittance of PE film is higher than that of PVC film.

The performance characteristics of solar greenhouse, the light characteristics of solar greenhouse are related to natural factors such as season, time, weather and greenhouse orientation, structure, building materials, management technology, etc., and change with the changes of the above factors.

1) High or celebratory intensity.

The seasonal and diurnal trends of light intensity in the solar greenhouse are basically the same as those in the outdoor area, but the light intensity of visible light is significantly weakened after entering the solar greenhouse through the plastic film, mainly due to the loss caused by the reflection of light, the absorption of the covering, the blocking of the skeleton, the aging of the covering material, the dust pollution and the reflection of water droplets.

The middle part of the solar greenhouse is the area with the best sunlight throughout the day, and the east and west ends form two active low-light areas before and after afternoon due to the shading effect of the gable, which shrink or expand with the change of solar altitude and disappear at noon. , vertically, the light intensity decreases from top to bottom. In the north-south direction, the light intensity gradually weakened from south to north, and the central pillar on the north side weakened significantly.

2} Illumination time.

In winter and spring, the solar greenhouse is covered with straw and thermal insulation quilts, etc., and is unveiled after sunrise, covered before sunset, artificially prolongs the indoor night time. Generally, from December to February of the following year, the indoor light time is only 6-8h

After the collapse in March, with the increase of temperature, the covering and heat preservation time can be appropriately shortened, and the indoor light time can reach 8-loh.

3) Light quality. The spectral composition of the chamber is related to the nature of the covering material, in addition to the height of the sun. The ultraviolet transmittance rate of plastic thin film is relatively high, which is conducive to the healthy growth of plants, and also promotes the synthesis of anthocyanins and VE, among which the ultraviolet transmittance of PE film is higher than that of PVC film.

Advantages of the solar greenhouse sedan car:

1. The lighting of the front and rear slopes of vegetables cultivated in the solar greenhouse is uniform and consistent;

2. The temperature change of the solar greenhouse is reasonable;

3. It is suitable for dense planting and repentance;

4. The greenhouse span is large, the scale is large, and the effective space is large;

Bique Liang 5, good thermal insulation effect;

6. Save energy and make full use of solar energy;

7. The measures are simple and easy to build;

8. The possibility of harm is small.

Fig.1 Basic structure of solar greenhouse.

1.Front roof 2Cold-proof ditch 3Straw curtain 4Rear roof 5North Wall.

1) North wall and east and west gables.

It is made of bricks, stones, or rammed earth, grass and mud. Opaque, the main function is to support the roof, prevent cold air from penetrating into the room, block the heat exchange between indoor and outdoor, and is the enclosure part of the greenhouse. There are two kinds of wall structures, one is a single wall, that is, it is built by a single brick, stone, tamped soil or grass and mud stack; The other is made of a variety of materials (bricks, soil, stone, cinders, polystyrene boards, etc.) layered and composite.

2) Front roofing.

Also known as daylighting roof, it is composed of transparent covering materials and supporting structures (arches, tie rods, columns, etc.). Its function is to let the daytime sunlight penetrate into the greenhouse, on the one hand, to meet the needs of horticultural crops photosynthesis, on the other hand, to meet the needs of greenhouse heat storage. At night, in order to prevent heat dissipation from the front roof, cover the outside of the roof with insulation covering materials such as straw, reed curtains, and thermal insulation quilts.

In the cold areas of the north, in order to enhance the thermal insulation capacity, the external thermal insulation covering material is set up in two layers, the first layer is the main covering layer, and more straw, reed curtain and thermal insulation quilt are used; The second layer is the auxiliary covering layer, which is padded between the light-transmitting covering material and the main covering layer when used, and uses several layers of kraft paper synthetic paper quilts, old plastic films, non-woven fabrics, etc. In some rainy areas in the south, in order to prevent the rain from wetting the straw curtain, prevent it from losing its heat preservation and prolong its service life, a layer of ordinary plastic film is added to the straw curtain. After sunrise in the morning, when the temperature rises, the outer covering layer is rolled up and placed on the back roof, so that sunlight can enter the room and the greenhouse accumulates heat; In the evening, when the indoor temperature drops to a certain level, put down the outer roof insulation material to keep warm.

There are two types of front roofs: single inclined and arched.

The function of the cold ditch is to prevent the heat from the interior from flowing out of the outdoors laterally through the soil.

3) Rear roofing.

It is composed of a bracket of a coffin, purlin and rafters, and is paved with straw, grass mud, cinder, grass or cement prefabricated slabs. The main functions are: connecting the front roof and the north wall, the east and west gables, and the insulation and load-bearing.

The skeleton of the greenhouse has bamboo, wood or steel pipes, steel bars, and cement steel reinforcement components. Rural or self-employed operators far from the city mainly use earthen walls, bamboo and wood structures. This type of greenhouse has a low one-time investment and is easy to build, but the ability to resist disasters (such as heavy rain, strong winds, etc.) is weak, and the service life is short, and it needs to be repaired every year.

In the suburbs of the city, collectively operated or state-run, the economic strength is dominated by brick walls and steel frames. This kind of greenhouse has a high cost, a large one-time investment, and is relatively complex to build, but it has strong disaster resistance, long service life, and does not need to be repaired every year. At present, there are all-cement structures in between, including gables and back walls made of cement and cement supports; There are also brick walls and cement supports.

This type of greenhouse investment is somewhere in between, and is an option in areas where the economy is not abundant, but there is some strength.

China's "annual vegetable production" – that is, agricultural production in spring, summer, autumn and winter that is not affected by the climate – can be basically summed up as "solar greenhouses in the north and plastic greenhouses in the south." "A plastic greenhouse is a long row of plastic greenhouses with a near-semicircular cross-section, with no supporting walls except for a curved skeleton. The low latitude in the south is convenient for sunlight to shine from the north and south, and the requirements for thermal insulation are not as high as those in the north, which is enough to meet the needs.

As for the solar greenhouse, its cross-section is relatively close to a quarter of the circle, the area is mostly half an acre to an acre, and it can be arranged quite densely, with a façade made of soil and straw, and the curved side facing south is covered with light-transmitting material. In this way, the southerly winter sunlight can be fully utilized, and the wall can also be used to absorb heat during the day and dissipate heat at night to ensure the stability of the indoor temperature. The solar greenhouse is a remarkable creation in China, highly adapted to winter agricultural production in the north temperate zone.

In the 1920s, the Japanese first introduced a greenhouse similar to the structure of a solar greenhouse in Liaoning, among which the more representative is the "Anshan Type 1" greenhouse, the wall is mainly a brick wall, and the covering material is mostly glass, which can be seen as a high-end goods, only a few people can enjoy the products in the greenhouse, mainly used to produce vegetables such as leeks in winter. After the 1960s, with the gradual development of petrochemical industry, North China began to have a "solar greenhouse" with plastic film as the covering material, and the structure was basically the same as that of the early greenhouse in Liaoning, but the cost was greatly reduced. The wall is made of mud, straw mixture, the effect of maintaining the temperature is better, to this day, the solar greenhouse in Shandong has become the main production place of winter vegetables, the more representative is the "Shouguang 5 type" solar greenhouse.

The galvanized steel skeleton mentioned by the technician is a structure such as trusses and columns that are used to support the curved covering material. Galvanized steel is the mainstream frame material for all types of greenhouses in China, and is popular because of its low cost, corrosion resistance and other characteristics. The steel material of galvanized steel is mostly ** material.

Solar greenhouse is the abbreviation of energy-saving solar greenhouse, also known as greenhouse, is a type of greenhouse unique in northern China. This is a type of greenhouse that is not heated indoors, and even in the coldest season, it relies only on sunlight to maintain a certain temperature level indoors to meet the needs of vegetable crop growth. The solar greenhouse is composed of three parts: the enclosure wall, the rear roof and the front roof.

The front roof adopts transparent covering material, uses solar radiation energy as the heat source, has the function of heat storage and heat preservation, and can be used in the cultivation facilities for vegetable production in the cold season of winter and spring without artificial heating or a very small amount of artificial heating. It has the characteristics of simple structure, low cost and energy saving, and is a unique horticultural plant cultivation facility in China. Orientation of the greenhouseThe orientation of the greenhouse refers to the direction of the ridge of the greenhouse.

Greenhouses are generally located in the north facing south, extending from east to west, and the lighting surface is facing due south to fully illuminate. Northeast region winter morning temperature is low, greenhouse can not be unveiled after sunrise to see the light, greenhouse direction can be appropriately inclined to the south and west to extend the afternoon light time, in order to accumulate heat, increase the night temperature in the greenhouse, but should be controlled within 10 °, otherwise the adverse effect on other seasons lighting. The shape of the lighting surface is the front roof.

The inclination angle of the daylighting surface needs to be increased in winter, and the combination of circle and parabola is currently the most used. There must be enough space at the foot of the roof before the distance, which is convenient for personnel to operate, and is suitable for the growth of tall crops. Considering the above factors, the lighting surface should be built with a radius of 4m arc, that is, the greenhouse with an arch or parabolic roof effect is good.

The elevation angle and width of the rear roof are also called back slopes.

Introduction: Solar greenhouse is the abbreviation of energy-saving solar greenhouse, also known as greenhouse, which is the northern region of China.

A unique type of greenhouse. It is a kind of greenhouse that is not heated indoors, and even in the coldest season, it only relies on sunlight to maintain a certain temperature level indoors to meet the needs of vegetable crop growth. Performance:

The light transmittance of energy-saving solar greenhouses is generally more than 60% and 80%, and the temperature difference between indoor and outdoor can be maintained at 21 to 25 degrees Celsius.

Above. Daylighting, on the one hand, solar radiation.

It is the most important energy to maintain the temperature of a solar greenhouse or to maintain heat balance**; On the other hand, solar radiation is the photosynthesis of crops.

of the only light source. Historical origins: The origins of greenhouses can be traced back to Qin Shi Huang.

Period, according to the scholar Wei Hong in the "Preface to the Ancient Civil Servant Book of the Edict", it was recorded that "Qin burned the book, fearing that the world would not change the law, and all the people who came to worship the lang, 700 people before and after, and it was a dense melon planted in the middle temperature of the Lishan Mausoleum Valley." "The era in which he lived was based on the burning of books and the pit of Confucianism for more than 200 years, and his records must be based on word-of-mouth history. Yan Shigu, a scholar of the Tang Dynasty, said in the annotation of "Hanshu, Volume 88, Confucianism Biography 58": "Now Xinfeng County.

The place of wet soup is called "Confucian Township", where the "place of wet soup" should be what Wei Hong said, "the middle temperature of Lishan Linggu", which further consolidated Wei Hong's credibility. Wei Hong's account of Qin Shi Huang reveals a valuable piece of agricultural technical information, that is, during the Qin Shi Huang period, the Chinese had invented greenhouse technology.