【作者】 乔正卫；

【导师】 邹志荣；

【作者基本信息】 西北农林科技大学 ， 农业生物环境与能源工程， 2008， 硕士

【摘要】 日光温室热量总损失的70%以上是通过前屋面散失的。目前,日光温室外覆盖保温材料有草苫等传统材料和保温被,但存在质量不均、防水性差、污染薄膜或价格过高不易推广等问题。所以开发性能良好,价格低廉的新型保温被仍有必要。选择多种材料,制作保温被,通过室内试验测试其性能,根据其结果再制作保温被,采用室外试验检验其保温性。在室内试验中,首先选择毛毡、喷胶棉、粗羊毛和PE发泡材料作保温芯材,牛津布和单面涂层防雨布作面料,还准备了铝箔反射材料,制作了6种保温被。采用静态热箱法,以草帘和2 kg/m2的毛毡保温被作为对照,测试了6种保温被的保温性;采用重量法,土工布综合强力机和人工热风老化法测试了前3种保温被的防水性,机械强度和耐老化性。结果表明:(1)采用“外层材料+塑料薄膜+芯材+内层材料”结构的1号和3号保温被吸水率为3.88%和6.75%,较2号保温被吸水率17.66%小,此结构具有良好的防水性。(2)1号、2号和3号保温被的机械强度分别为324.8、216.4和172.7 N/cm,保温被的强度取决于内外层(防护层)材料的强度特性,牛津布和单面涂层防雨布具有较高的强度。(3)人工老化后3种保温被的强度依次降低10.2%、7.0%和11.3%,牛津布和单面涂层防雨布具有良好的耐老化性。(4)在21和37W热源功率下,两层喷胶棉制作的保温被的传热系数为3.10和3.26 W/(m2·K),较草帘(3.52和3.61 W/(m2·K))和对照保温被(3.22和3.28 W/(m2·K))小,600 g/m2羊毛制作的保温被为3.42和3.49 W/(m2·K),也小于草帘(3.69和3.60 W/(m2·K))和对照保温被(3.64和3.53 W/(m2·K)),采用400 g/m2喷胶棉或600 g/m2以上羊毛制作保温被,其保温性超过草帘和对照保温被。选用牛津布作内外层材料,采用“外层材料+塑料薄膜+芯材+内层材料”结构制作了含600 g/m2羊毛的羊毛保温被和含400 g/m2羊毛夹层的毛毡羊毛保温被,通过室外小拱棚试验,以1 kg/m2和2 kg/m2的毛毡保温被作为对照,测试了其保温性。结果表明:(1)羊毛保温被覆盖的小拱棚的平均棚内气温为23.1℃、平均土温为27.7℃,通过羊毛保温被的平均热流为-11.53 W/m2,其平均传热系数为1.45 W/(m2·K),1 kg/m2毛毡保温被覆盖的平均棚内气温为22.4℃、平均土温为27.6℃,通过此保温被的平均热流为-15.91 W/m2,其平均传热系数为2.43 W/(m2·K),羊毛保温被的保温性优于1 kg/m2的毛毡保温被。(2)毛毡羊毛保温被覆盖的小拱棚的平均棚内气温为24.3℃、平均土温为27.6℃,其平均传热系数为1.35 W/(m2·K);2 kg/m2毛毡保温被覆盖的平均棚内气温为23.9℃、平均土温为27.5℃,其平均传热系数为1.39 W/(m2·K),毛毡羊毛保温被的保温性超过2 kg/m2的毛毡保温被。成本分析表明,羊毛保温被为11.7元/m2,毛毡羊毛保温被为14.3元/m2,分别比1 kg/m2毛毡保温被12.2元/m2和2 kg/m2毛毡保温被16元/m2低,羊毛芯保温被可替代现有的毛毡保温被。更多还原

【Abstract】 The heat loss through the front roof accounts for mort than 70% of the total heat loss of sunlight greenhouse. At present, outside covering materials for heat preservation of sunlight greenhouse include traditional materials, such as straws, and heat preservation quilts. But there are problems of quality unevenness, poor waterproof and pollution to the film, or high price and difficulty in popularization. So the research and development of novel heat preservation quilts (HPQ) of good performance and low cost becomes a necessity.In this study, various materials were selected to make HPQs, and their performances were tested in laboratory. After getting the test results in laboratory, HPQs were remade and their heat preservation performance was tested by field experiment. In the lab test, six HPQs were made, adopting felt, spray-bonded unwoven fabric, coarse wool and Puffed PE as thermal insulation materials, using oxford and waterproof cloth with coat as covering materials, and using aluminum foil as reflecting material. The heat preservation of six HPQs was tested with static hot-box experiment to compare with that of straws and felt quilt with a flat density of 2kg/m2. The waterproof, mechanical strength and resistance to aging of the first three HPQs were tested with weighing method, strength tester and artificial aging. The results were listed as following:(1) HPQ 1 and HPQ 3 whose structure was“outside material + plastic film + core + inside material”showed a better waterproof with water absorption of 3.88% and 6.75%, less than that of HPQ 2, 17.66%. The structure had a perfect property of waterproof.(2) The mechanical strength of HPQ 1, HPQ 2 and HPQ 3 was 324.8, 216.4 and 172.7 N/cm, respectively. The mechanical strength of HPQ depended on the mechanical property of its inside and outside materials (defending layer). Oxford and waterproof cloth with coat had good performance in mechanical strength.(3) The mechanical strength of the first three HPQs declined by 10.2%, 7.0% and 11.3% in turn after the artificial aging. Oxford and waterproof cloth had nicer resistance to aging.(4) The heat-transfer coefficients of the HPQ made of spray-bonded unwoven fabric with a flat density of 400 g/m2 were 3.10 and 3.26 W/(m2·K), less than those of straws (3.52 and 3.61 W/(m2·K)) and those of contrasting HPQ (3.22 and 3.28 W/(m2·K)), under the heating power of 21 and 37 W. The heat-transfer coefficients of the HPQ made of wool with a flat density of 600 g/m2 were 3.42 and 3.49 W/(m2·K), also less than those of straws (3.69 and 3.60 W/(m2·K)) and those of contrasting HPQ (3.64 and 3.53 W/(m2·K)). The HPQ made of spray-bonded unwoven fabric with a flat density of 400 g/m2 or wool with a flat density of 600 g/m2 exceeded straws and the contrasting HPQ in heat preservation.Choosing oxford as inside and outside materials and adopting the structure of“outside material + plastic film + core + inside material”, wool HPQ including wool with a flat density of 600 g/m2 and felt wool HPQ including wool interlayer with a flat density of 600 g/m2 were made. Their heat preservation was tested by field small arch greenhouse experiment, compared with felt HPQ with a flat density of 1 kg/m2 and felt HPQ with a flat density of 2 kg/m2, and following results were obtained:(1) The small arch greenhouses covered with the wool HPQ got an average air temperature of 23.1℃and an average soil temperature of 27.7℃, and average heat flow through the wool HPQ was -11.53 W/m2 while its average heat-transfer coefficient was 1.45 W/(m2·K). The ones covered with the felt HPQ with a flat density of 1kg/m2 got the air temperature of 22.4℃and the soil temperature of 27.6℃, and the heat flow through the HPQ was -15.91 W/m2 while its heat-transfer coefficient was 2.43 W/(m2·K). The wool HPQ had a better heat preservation than the felt HPQ with a flat density of 1 kg/m2.(2) The ones covered with the felt wool HPQ got the air temperature of 24.3℃and the soil temperature of 27.6℃, and the heat-transfer coefficient of the HPQ was 1.35 W/(m2·K). The ones covered with the felt HPQ with a flat density of 2 kg/m2 got the air temperature of 23.9℃and the soil temperature of 27.5℃, and the heat-transfer coefficient of the HPQ was 1.39 W/(m2·K). Therefore the felt wool HPQ had a better heat preservation than the felt HPQ with a flat density of 2 kg/m2.Cost analysis indicated that, the cost of wool HPQ and felt wool HPQ was 11.7 $/m2 and 14.3 $/m2, lower than that of felt HPQ with a flat density of 1 kg/m2 and felt HPQ with a flat density of 2 kg/m2, 12.2 $/m2 and 16 $/m2, respectively. HPQs with wool core can act as substitutes to the current felt HPQs.更多还原