In nature, it absorbs heat during the day and dissipates heat at night, but as far as decoration materials are concerned, this material should not exist yet.
Even if there is, it is very expensive, but at least I have never heard of this material.
Do not rule out high-tech machines
Greenhouse materials that absorb heat during the day and fan wind at night.
Take a look at the column 20 140522 of CCTV7 Science Park, and search the thermal storage wall of unpaved villa.
What does the greenhouse use to keep warm?
The heating equipment of greenhouse includes boiler, circulating motor, heat exchanger, etc.
Heating energy includes coal, natural gas, oil, geothermal energy or solar energy.
The thermal insulation equipment is provided with a roller shutter deceleration motor,
The insulation blanket material includes external insulation cotton, non-woven fabric or straw curtain, and internal insulation film.
What are the heating methods in the greenhouse?
Producing out-of-season vegetables in winter is one of the effective ways to ensure the annual vegetable supply. Mainly refers to the spring and summer vegetables postponed in autumn and produced in advance in spring. Cold-proof measures must be taken when planting to achieve the purpose of early listing.
(1) site selection
In areas where vegetables are produced out of season in winter, it is required to choose places with warm climate, abundant sunshine, low altitude or hills in plain areas, convenient water sources, suitable soil conditions and wind barriers (such as mountain barriers or other buildings in the north) to avoid direct attacks by cold air.
(2) Variety selection
Cold-resistant, disease-resistant and early-maturing varieties should be selected for off-season vegetable production in winter, and autumn-delayed varieties should also be heat-resistant at seedling stage. For example, there are Update No.4, Update No.5, Xiang Yan No.9, Xiang Yan 10, Xiang Yan 1 1, Guangjiao No.2, Layou No.4, Eggplant Fengqie 1 and Fengqie No.2, Cucumber Jinza No.3, Jinza No.4 and Jinchun No.4.
(3) High-quality and efficient cultivation techniques
Greenhouse vegetables keep warm and cold in winter.
Seedling raising in nutrition bowl: The black plastic nutrition bowl has the functions of absorbing heat during the day and protecting roots at night. When the outside temperature is about-10℃, the temperature in the border is about 6 ~ 7℃, and the temperature in the nutrition pot is about 10℃, the seedlings grow slowly and will not be frozen.
Preparation of hot nutrient soil: chicken manure is hot manure, cow manure is breathable manure and rich in mucus. After they are decomposed, 20% is taken away and 60% is mixed with fine soil. This nutrient soil has good heat absorption and power generation performance, good seedling ecological environment, developed root system, strong absorption capacity and strong plant frost resistance. Root irrigation with rooting element during seedling division: Rooting element is reasonably prepared from several nutrient elements related to long roots, such as calcium, phosphorus and zinc. Calcium determines the thickness of roots, phosphorus determines the number of roots, and zinc determines the growth speed and length of roots. After using rooting agent, the root system can be increased by about 70% and the deep root can be increased by 25%. The root system is developed and the absorption capacity is strong, and seedlings and vines will not be frostbitten because of poor cold resistance caused by lack of water and elements.
Heat preservation and anti-freezing: the specific heat of water is higher than that of air, and the heat dissipation is slow. In winter, the indoor soil moisture content is moderate, the pore cracks in the plough layer are fine, the roots are not suspended, the soil is warm, and the roots are not damaged by freezing. Therefore, the frost damage of seedlings is mostly caused by lack of water. Therefore, pouring enough water before winter or when the weather is fine (watering above 20℃) can prevent freezing injury.
Heat preservation and cold protection of intertillage: the ground is hard, and hot air is restricted from entering the plough layer during the day, so the soil stores less heat energy. In addition, the hardened soil has large and deep cracks, poor aggregate structure, easy heat dissipation in the first half of the night, and low room temperature in the second half of the night, which is easy to cause freezing damage. Shallow intertillage can break the ground and close the seam, which can not only control the transpiration of groundwater to take away heat energy, but also keep moisture, keep warm, prevent cold and protect seedlings. ?
Spraying nutrients on leaves to resist cold: the temperature is low in winter, the light is weak, and the absorption capacity of roots is weak. Spraying photosynthetic micro-fertilizer on leaves can supplement the element deficiency caused by insufficient absorption of nutrients by roots. Spraying rice vinegar on leaves can inhibit bacteria and repel insects, and mixing with white sugar and calcium superphosphate can increase the sugar content and hardness of mesophyll and improve the cold resistance. After freezing injury, the leaf surface is alkaline atrophy, and spraying vinegar can reduce the degree of injury. It is advisable to use 100 ~ 300 times liquid, and use less or no growth hormone to prevent the cold resistance from decreasing.
Repeated drying in sunny days: the maximum temperature in the shed can reach above 32℃ in sunny morning in winter. At this time, it is necessary to dry it repeatedly, reduce the temperature difference between indoor and outdoor, and let the plants slowly adapt to the environment and grow healthily. Beware of sudden growth in one day and sudden cold in ten days, causing flash seedlings and freezing damage.
Supplementing carbon dioxide: the ratio of carbon and nitrogen to crop yield is 1: 1, and the demand for carbon and nitrogen ratio is 30: 1. At present, most farmers have realized the influence of nitrogen on crop yield, but neglected the influence of carbon on crop yield. In winter, vegetables in greenhouses grow yellow easily. The carbon dioxide produced by crop respiration and soil microbial decomposition at night can be absorbed after the sun comes out 1 hour, and it will be in a state of carbon hunger about 12 hours. When the temperature is high, the greenhouse film can be opened and closed to release external carbon dioxide and improve resistance and yield. When the temperature is low, closing the greenhouse and artificially supplementing carbon dioxide can enhance the cold resistance of crops and greatly increase the yield.
Cover in time to keep warm: in general greenhouses, heat is absorbed and stored during the day, and energy is released at night, accounting for 50% ~ 60% of the indoor total; Soil heat absorption and release accounts for 20% ~ 30%; Space thermal storage accounts for 20% ~ 30%. Depending on the temperature of the day, after covering 1 hour, the room temperature may remain around 18℃. It can be covered later when it is higher than 18℃, and earlier when it is lower than 18℃.
......& gt& gt
What are the heating methods for planting anti-season vegetables in greenhouses in winter?
Personally, I think it's cold in winter, so I can warm myself up and put a few coal stoves in it. . .
The regulation of temperature in greenhouse mainly refers to two aspects: heat preservation and cooling. Greenhouse heat preservation mainly occurs in late autumn, winter and spring, and generally ends from 10 to the middle and late April. Heating and insulation are usually carried out by adjusting methods such as modulating heat, stove, electric heating wire, water heating, air heating, steam and covering. In practice, sometimes several methods need to be used together.
First, rational layout
When building a greenhouse, it is necessary to have conditions that can fully accept sunlight and avoid shading. When choosing agricultural film, it is best to choose a film that does not drip. The roof film of greenhouse must use new film, not old film. The larger the greenhouse area, the slower the cooling and the better the heat preservation effect.
Second, multi-layer coverage
When the frost comes, when the daily minimum temperature is 0℃-4℃, build a small arch shed in the greenhouse and cover it with sunshade net or non-woven fabric. When the lowest temperature outside the greenhouse drops below 0℃, the skirts around the greenhouse are covered with grass pieces, the small arch shed in the greenhouse is covered with two layers of films, a sunshade net or non-woven fabric is sandwiched between the two layers of films, and the small arch shed near the two sides of the greenhouse is covered with a layer of grass pieces. If the temperature is still too low, you can cover a sunshade net on the top film of the greenhouse, or even cover another film at a distance of 10-20 cm from the top film in the greenhouse.
Third, temporary heating.
When the outside temperature is extremely low and the multi-layer coverage cannot meet the requirements, temporary heating measures should be considered. These methods are:
1. Open flame heating Open flame heating cannot burn firewood or coal in greenhouse facilities, but charcoal can be used for heating, but attention should be paid to the harm of toxic gases such as carbon monoxide.
2. Heating with electric heating wire Bury the electric heating wire in the greenhouse soil, and heat it with electric heating wire to raise the soil temperature. This method is widely used in seedling raising and protected cultivation in winter and spring, with good effect, but the use cost is high.
3. Hot stove heating is near power plants or factories with boilers, and the waste heat can be used for heating. This method has low cost and good effect, and is especially suitable for multi-span greenhouses or long-span greenhouses.
4. Hot water bag The hot water bag is placed in the greenhouse during the day. Water has a large specific heat, which can absorb solar energy during the day and convert it into heat energy for storage, and gradually release heat energy when it cools down at night, thus increasing the temperature of the greenhouse.
5. Water heating and heating The water is sent to the boiler for heating, so that the water becomes steam, hot water or warm water, and is introduced into the iron pipe or radiator in the protection facility through the conveying iron pipe for heating. After cooling, it will return to the boiler from return pipe for reheating and continue the cycle.
Fourth, fill up the brewing heat.
When preparing soil, making border or making seedbed, the soil is full of brewing heat, such as fresh garbage, manure, cow dung, pig manure and so on. Then the garden soil is buried, and the temperature of soil and air is increased by using the heat released by brewing thermal fermentation. This method has a good effect on seedling raising of fruits and vegetables in winter and early-maturing cultivation of leafy vegetables such as spinach and sunflower. Pig cow dung is often used as brewing heat in rural areas of our province, mixed with some chicken, sheep dung or human urine. Hot drinks must be fresh, and they should be stepped on the bed in layers, with a thickness of 20-30 cm and a water content of about 70%.
Verb (abbreviation of verb) ecological heat insulation
30 days before sowing or planting in winter and spring, soil preparation, application of base fertilizer, covering with plastic film 10-30 days, preheating the greenhouse, and raising the soil temperature. Open a cold ditch with a width of 25-30 cm around the shed, and fill it with horse manure, chicken manure, sheep manure, sawdust and firewood. And covered with soil slightly higher than the ground. When planting seedlings, the seedlings should be flat or slightly higher than the ground, and it is not advisable to plant seedlings too deeply. After planting, root water should be poured quickly, and it is best to use deep well water to promote slow seedling. If there is no plastic film, it is necessary to turn the soil between rows many times in the early stage of growth, which can improve the ground temperature and preserve moisture.
Six, timely antifreeze
Before the arrival of the cold wave, if there is no condition to build a greenhouse, irrigation can be carried out when the soil is dry, which has a certain antifreeze effect. When the temperature outside the shed is -3℃-4℃, the seedlings in the shed will not be frozen. Before frost, smoking outside the shed can increase the temperature around the shed by 1℃-2℃, and the temperature inside the shed will also increase accordingly. In addition, cr-6 plant cold-resistant agent can be sprayed 75 times, combined with soaking seeds with 50 times solution before sowing, soaking roots with 100 times solution during transplanting, or spraying on leaves. When pepper seedlings have 3-4 leaves, spraying 0.5% calcium chloride solution twice continuously for 7 days 1 time has good antifreeze effect.
Are there any special precautions for making a greenhouse?
1 building
A greenhouse is a facility for cultivating plants in a season that is not suitable for their growth. The basic feature of greenhouse is that it can transmit light and keep warm, so as to meet the needs of plant growth. There are many kinds of greenhouses, which are divided into glass greenhouses and plastic greenhouses according to different materials and heating conditions. Single greenhouse and multi-span greenhouse; Single-roof greenhouse and double-roof greenhouse; Heated greenhouse, unheated greenhouse, etc. According to different functions, greenhouses can be divided into planting greenhouses, breeding greenhouses, ornamental greenhouses and commercial greenhouses. Now the most mentioned is the vegetable greenhouse.
The technicians of Daewoo Shunlong Agricultural Equipment Technical Service Co., Ltd. put forward several aspects that should be paid attention to in greenhouse construction:
First, strengthen the heat preservation of the greenhouse.
The heat stored in the greenhouse is mainly the ground, three walls and the back slope. Therefore, in order to improve the thermal insulation performance of greenhouse, we need to pay attention to the following points:
1. In order to raise the soil temperature, a semi-underground boundary was built. When building a greenhouse, the indoor frame should be 30 ~ 40 cm lower than the outdoor ground, so that the indoor soil temperature drops more slowly than the outdoor and the heat preservation effect is better.
2. Strengthen the thickness of greenhouse wall and back slope. Practice has proved that in order to resist the disastrous weather in winter, the bottom of the greenhouse soil wall should be 2 meters wide and the top should be 1.5 meters wide, which is trapezoidal. If the brick wall is built, the thickness should be no less than 1.2m, that is, 50cm inside is the heat absorption layer, 80cm inside is filled with baled wheat straw as the thermal insulation layer, and 18cm outside is the cold protection layer. In winter, 30 cm thick corn stalks should be used outside the wall.
3. Set the elevation angle of the back slope of the greenhouse.
Generally speaking, the back slope faces north. The elevation angle of the back slope is about 45 degrees, which can enhance the light receiving and heat storage capacity of the back slope. Enhance thermal insulation.
Second, increase the usable area of the greenhouse.
The investment in greenhouses is generally relatively high, so how to achieve small investment and high income? By appropriately increasing the span and thickness, the indoor area can be expanded a lot with only a small amount of investment. For example, a greenhouse with a length of 100 m and a width of 10 m can increase its usable area by 11%if the greenhouse extends to the south. The ideal roof angle can be achieved only by increasing the height of the roof by 20 cm. Increasing the length of greenhouse is also a way to reduce investment and expand planting area. More importantly, after the indoor space increases, the temperature changes smoothly, especially at night.
Third, plastic film mulching in greenhouses should be well protected.
When exposed to sunlight during the day, the temperature area covered by film is the largest, and the heat dissipation surface covered by film is the largest at night. Because of the large area of film mulching, the insulation effect of film mulching is very important. Therefore, it is necessary to protect the coverage of movies.
Misunderstandings and improvement measures of arch shed construction
Because of the high land utilization rate and simple construction, many vegetable farmers who used to grow open-air vegetables began to build arch sheds. However, many vegetable farmers have some misunderstandings when building arched sheds, such as: all the columns in the arched shed are vertical to the ground, the shed surface is straight, and there are no water retaining walls on both sides of the arched shed. So how can vegetable farmers improve these misunderstandings? Here, Daewoo Shunlong Agricultural Equipment Technical Service Agriculture Co., Ltd. introduces some methods, hoping to help vegetable farmers.
The vertical embedding of columns at both sides and ends of the arched shed is changed to inclined embedding.
Vegetable farmers are used to burying all the columns in the arch shed vertically when installing columns in the arch shed. When the arched shed encounters strong wind, it will tilt when it is blown by the wind, which will lead to broken columns and the collapse of the arched shed in serious cases. Practice has proved that the compressive capacity of arched shed with inclined concealed columns can be significantly improved. Therefore, when vegetable farmers decide to build an arched shed, they should bury a row of columns vertically in the middle of the arched shed, and other columns on both sides of the arched shed should be buried obliquely. Take the arch shed built in north-south direction as an example. If the number of columns required for arch shed construction is odd, a row of columns in the middle of the arch shed should be set vertically. For the column near the east side of the middle column, vegetable farmers should lean to the east side, and the inclination angle of the column is getting bigger and bigger. But vegetable farmers should also pay attention to the fact that the inclination angle of the outermost column of the shed should not exceed 2 degrees. The column on the west side of the column in the arch shed should be inclined to the west when buried, and the inclination angle should be symmetrical with the column on the east side. For the columns at the north and south ends of the arch shed, they should also be slightly tilted outward. When these columns are connected into a whole with bamboo poles, their mutual support ability is enhanced, which can greatly improve the wind resistance and compression resistance of the arch shed. After this improvement, if there is a west wind, stand on the west side of the greenhouse ... >; & gt
What is the principle of greenhouse?
Adopt the principle of heat absorption and heat preservation. On the one hand, the materials in the greenhouse can absorb light and heat, on the other hand, they can also keep warm and prevent heat loss.
Also, the greenhouse can use heating equipment, the most commonly used is heating, and the most commonly used greenhouse is round wing heating, because it is cheaper. Solar greenhouse has better thermal insulation performance and lower cost.
Why is the vegetable greenhouse hot?
The air circulation is poor, forming a microclimate, and the film is an endothermic material, so heat is formed.
What kinds of thermal insulation materials are covered outside the solar greenhouse?
The thermal insulation covering materials of solar greenhouse can be divided into two categories: one is the external thermal insulation covering materials, including grass (curtain), paper quilt, quilt, etc., which are mainly used for the external covering of greenhouse; The other kind is internal hanging insulation covering materials, including agricultural non-woven fabrics (also known as non-woven fabrics or harvesting cloths) and plastic films, which are mainly used for hanging insulation curtains (also known as hot curtains or secondary curtains) or adding small and medium-sized arches in greenhouses.
The requirements of external thermal insulation materials in solar greenhouse are high thermal insulation, non-heat absorption, light weight, durability and low cost; The requirements of internal thermal insulation covering materials are high thermal insulation, fog drop prevention, light weight, durability, easy folding and reasonable price.
(1) Caocao (curtain): Caocao is the most widely used insulation covering material in solar greenhouse production in China at present. The thermal insulation effect of straw mats is generally 5 ~ 6℃, which varies greatly due to the weaving thickness and density of straw mats and the dry and wet degree of materials used, and is also affected by indoor and outdoor temperature difference and weather conditions. The thicker and denser the straw mat is woven, the drier the material is, and the better the insulation effect is. A thatched roof can be made of straw, cattail, cereal grass and Lu Hua. And most of them are thatched with straw. However, no matter which kind of raw material is selected, it is required that the careless weaving should be dense, the gap should be small and the thickness should reach 6~8 cm. The weaving width of grass is generally 1.2~ 1.6 m, and a larger width is beneficial to improve its thermal insulation effect. The characteristics of grass quilt are good thermal insulation effect, convenient material acquisition and low cost, but the preparation of grass quilt is labor-intensive and its durability is not ideal, and it can only be used for about 3 years. Coupled with the weight of grass, it is time-consuming and laborious to roll up at ordinary times, and the weight is further increased after being absorbed by rain and snow, which makes it more difficult to roll up and it is difficult to realize automatic operation. Nevertheless, there is still a lack of other materials with good thermal insulation performance, low cost and suitable for mechanized operation to replace kusnezoff monkshood.
(2) Paper quilt: In cold season or cold area, in order to make up for the lack of thermal insulation ability of grass, a layer of paper quilt can be covered under the grass. Paper quilt is usually sewn with 4~6 layers of old cement bag paper or new kraft paper into a kind of thermal insulation covering material similar to grass size. According to the observation in Shenyang, the thermal insulation effect of the paper quilt made of four layers of kraft paper can reach 6.8℃, while the thermal insulation capacity of one layer of grass is 10℃ under the same conditions. After covering the grass with paper, it not only increases the air isolation layer, but also makes up for the loose grass and high heat transfer rate, so it has a significant effect on improving the indoor temperature. According to estimates, adding a layer of paper quilt made of four layers of kraft paper under the grass can increase the indoor temperature by 3 ~ 5℃. Although the paper quilt has good thermal insulation effect, it has high investment and is easy to be damaged by moisture in rainy and snowy areas in winter and early spring, so some places use old films instead of paper quilts.
(3) Quilts: In the northeast, northwest and cold regions, quilts are also used for greenhouse coverage in winter. The quilt is made of cotton cloth (or packaging cloth) and cotton wadding (cotton or short-staple cotton with the same outer flowers can be used), which has good thermal insulation performance, and it is about 10℃ in cold regions, which is higher than that of grass or paper quilts. The cost of quilts is very high. Although the one-time investment is large, the service life is long. In some places, in order to reduce costs, woven bags are used instead of cotton cloth, and asbestos or fiber cotton is used instead of cotton wool as insulation quilts, which can also play a good insulation effect.
(4) Agricultural non-woven fabrics: non-woven fabrics are non-woven fabrics made of polyester raw materials. The polyester fibers used are long and short, and the cross section is round or oval. Non-woven fabrics made of long fibers with oval cross-section have compact structure and good thermal insulation performance, but the thermal insulation capacity of non-woven fabrics with a weight of 20 grams per square meter is only 1.5℃, which is not as good as that of PVC films with a weight of 0.1mm.