(Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; 2 Institute of Modern Agricultural Science and Engineering, Tongji University, Shanghai 20(1)92) Comprehensive analysis of factors such as insulation performance, fracture strength and cost performance, density of 100g/m2 spunbond filament non-woven The cloth composite plastic film is an ideal greenhouse insulation material.
In recent years, China has made some progress in the development and development of facilities and horticultural covering materials, but mainly concentrated on the research and development of external thermal insulation materials. The internal thermal insulation materials have not received enough attention, and most of them still use traditional straw curtains, plastic films, and Puxi. , paper quilts, quilts, etc., but these materials are easy to break, the service life is short, and it is difficult to popularize. Insulation materials in developed countries mainly use aluminum foil insulation curtains with dual functions of heat preservation and shading, but they are expensive and unsuitable for large-scale use in China. China is a big textile country with abundant textile raw materials. How to deal with China's fund projects: Zhejiang Province's major scientific and technological research projects (021102543) facilities horticultural research u actual situation, the development of screening cheap, heat-insulating internal insulation materials, has an important significance. To this end, we have carried out screening and application tests for new types of greenhouse insulation materials, and the results are reported below.
1Materials and methods li for testing new materials for testing new materials for short-fiber or filament polyester non-woven fabrics alone and composite materials with plastic film, composite adhesive heating integrated composite and traditional seam compounding method, The composite film is a 12-wire plastic film. The control is a 12-wire plastic film (Table 1). Table 1 is a new type of greenhouse insulation material. New greenhouse insulation material. Single non-woven material 120g/m2 acupuncture staple fiber. Woven fabric 200g/m2 needled staple fiber line stitching reinforced non-woven fabric 100g/m2 spunbonded filament non-woven fabric 200g/m2 spunbonded filament non-woven fabric and plastic film 120g/m2 needled staple fiber Woven fabric joint film composite material 200g/m2 needle punched staple fiber non-woven fabric seam composite film 100g/m2 spunbond filament non-woven fabric composite film 200g/m2 spunbond filament non-woven fabric composite film 1.2 insulation Application test of materials From January 21st to January 29th, 2004, the first application test of thermal insulation covering materials was carried out in a 7-story plastic greenhouse in the north-south direction of the facility horticultural engineering center of Zhejiang Academy of Agricultural Sciences. In order to overcome the error, the experiment set up a small arch shed in the middle of the three buildings, and the two consecutive buildings on both sides were normal cultivation and production. In the middle of each test small arch shed (0. 20m), the temperature and humidity automatic recorder ZD-20 produced by Zhejiang University was set to record the temperature and humidity. The small arch shed opened all the insulation materials at 8:30 in the morning, covered the insulation materials at 16:30 in the afternoon, and began to record data.
The endowment time is from PM4:30 to AM8:30 on the next day, and the data recording interval is 30min. 120g/m2 short-fiber non-woven fabric stitching composite film, 200g/m2 is selected from the 8 kinds of new insulation materials for the first test. Short-fiber non-woven fabric seam composite film, 100g/m2 spunbond filament nonwoven fabric composite film and 200g/m2 spunbond filament nonwoven fabric composite film will be second from February 11th to March 10th. The application test of the secondary insulation material is based on the use of a layer of old 12-filament plastic film commonly used in production. The width and height of the small arch shed used in the test were the same as those in the first test, and the length was 40 m. The temperature record was the same as the first test, and the repetition was three times. The arrangement in the greenhouse was randomly arranged.
1.3 Insulation material performance test The insulation rate, heat transfer coefficient, Crow value and breaking strength of the four new insulation materials and the control plastic film tested in the second application of the insulation materials were tested. The test method for the breaking strength and thermal insulation property of the material is higher than the average temperature of the night in the small arch shed covered by the thermal insulation effect of the insulation material of the National People's Republic of China. 22nd to 23rd, 23rd to 24th, 27th to 28th, and 28th to 29th, the lower temperature night, whether it is needle-punched staple fiber or spunbonded filament nonwoven fabric, non-woven fabric and film The thermal insulation capacity of composite insulation materials is higher than that of single non-woven insulation materials (-A, B, C, D). On the night of January 27, there were 4 small 20d and 23d covering composite insulation materials of non-woven fabrics and films, and the temperature of the small-arched sheds of the old plastic film and the 120g/m2 short-fiber non-woven fabric was not significant. In addition to the difference, all the composite insulation materials of the remaining test days are significantly different from the old plastic film, but a variety of old insulation materials and a layer of old 12 silk plastic film plus a layer of old 100g/m2 acrylic fabric No significant difference (―A, B).
2.2 Insulation performance and breaking strength of composite thermal insulation materials The thermal insulation rate and Crow value of four composite thermal insulation materials are about 3 times and 5 times higher than that of 12-filament plastic film, and the heat transfer coefficient is only about 20%. Compared with the thermal insulation performance of the composite thermal insulation material, the spunbonded filament nonwoven composite film is superior to the staple fiber non-woven composite film. Whether it is straight or transverse fracture strength, the four composite insulation materials should be much higher than the control. The spunbonded filament nonwoven fabric composite film should also be shown in Table 2. Composite insulation material insulation performance and fracture strength measurement items and indicators 12 silk Plastic fiber stitching laminating filaments overall laminating film insulation performance insulation rate /% heat transfer coefficient / W. Crowe value breaking strength (N) straight lateral B: comparison of line stitching lamination control D: no longer suspending Comparison of membrane and control 12 silk fort material thin abdomen â–¡ acupuncture staple fiber 200 rows m reinforced non-membrane acupuncture staple fiber 120 rows of seam reinforcement non-film continuous greenhouse greenhouse covered with different insulation materials small arch shed in the night average temperature ( 01―21~01―29) p/诹è¡æ™¡ The night average temperature difference in the small arch shed covered with different insulation materials in the greenhouse at the lowest temperature (01-27~01-28) The fiber non-woven fabric stitching composite film is about 2 times higher (Table 2).
3 Discussion The performance of the internal thermal insulation material is mainly considered from the aspects of heat preservation, strength, durability, service life and cost. In addition, due to the mechanical film coating device in the facility gardening production application, the mechanical operation adaptability is also one of the selection indicators. The conduction heat loss in the small arch shed is closely related to the thermal conductivity of the covering material and the thickness of the covering material. By increasing the thickness of the covering material and selecting a material with a small heat transfer coefficient, the purpose of reducing the conduction heat loss can be achieved.
This test found that the composite insulation material with a density of 100g/m2 or more in the southern greenhouse can play a certain role in heat preservation. The increase in thickness of the cover causes the greenhouse load, the labor intensity of the uncovering, the power of the mechanical film and the production cost, etc. Therefore, the use of transmission, more real temperature materials, more is the application of needle felt, blanket scrap and polypropylene and other materials, its low price, but low fiber strength, poor weather resistance, especially for mechanical film, large pull, easy The rolling bag phenomenon occurs, and the heat preservation performance of the heat preservation is weakened. Polyester material has high strength, good weather resistance and moderate price. The composite insulation material made of non-woven fabric and plastic film made of it has good thermal insulation performance and mechanical strength. At present, the heat preservation is processed, and more is made by a simple sewing process. The process is simple and low in cost, but there are problems such as water seepage at the needle eye of the sewing, which causes the heat preservation performance to be weakened, and the burden of the mechanical winding mechanism increases. This test also found that the composite insulation material made by the seaming process is difficult to cut, and the wire is peeled off after cutting or even the separation of the film and the nonwoven fabric. The composite thermal insulation material produced by the integral bonding process can well overcome the shortcomings of the insulation process, and the production process is simple and worth promoting.
The price/performance ratio of agricultural insulation materials affects an important factor in its promotion and application. At present, the most popular aluminum foil used in modern greenhouses is the most expensive. The lowest price is also above 15 yuan/m2. The price of common grasshoppers is low, about 1.8 yuan/m2, but it can only be used for 1 year and consumes 1.8 yuan per year. /m2. The insulation material of the 100g/m2 spunbonded filament monolithic composite film produced by this test is expected to be about 2 yuan/m2 after mass production of single-layer laminating film.
The price of double-layer laminating film is about 3 yuan/m2, which can be used for 5 years, and the average annual consumption is 0.4 yuan/m2 to 0.6 yuan/m2, which has outstanding cost performance.
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