石蜡基碳纳米管复合相变材料的制备及在冷藏陈列柜中的应用研究

发布时间：2018-02-01 09:25

  本文关键词： 冷藏陈列柜 复合相变材料 多壁碳纳米管 强化传热 复合搁架 食品包　出处：《郑州轻工业学院》2017年硕士论文　论文类型：学位论文

【摘要】：立式敞开式食品冷藏陈列柜作为食品冷链的末端设备,对保证食品品质和安全起到重要作用。但其普遍存在柜内风幕冷量外溢、柜内温度分布不均、融霜过程中食品温度回升较大等缺点,因此本文从优化风幕回风口结构、强化柜内食品传热、改善复合搁架温度均匀性、减少融霜期间食品温度回升等方面开展理论与实验研究,本文主要研究内容和结论如下:1.通过添加挡风板和增加底板长度来克服冷藏陈列柜风幕回风口冷量外溢问题。结果表明:添加挡风板和增加底板长度能有效减小风幕回风口处的冷量外溢。添加挡风板使下侧食品包温度可以减小0.16~0.65K;底板长度增加0~200mm可以降低底板上食品包温度,同时可冷却底板上增加的食品包,保证其满足冷藏温度要求。2.实验条件对差示扫描量热仪测试相变材料热物性有较大影响,通过改变升温速率、样品质量、气氛流量等实验条件对其进行了实验研究。结果表明:升温速率和样品质量对样品相变温度和相变潜热影响较大,气氛流量对其影响较小,为了保证实验结果准确性,样品质量应在10.0mg左右,并采用较低(≤5K/min)的升温速率。3.为提高石蜡RT4的导热性能,制备了六种多壁碳纳米管添加量的复合相变材料,并对其热物性及稳定性进行实验研究。结果表明:随着多壁碳纳米管添加量的增加,复合相变材料的相变温度基本不变,相变潜热逐渐减小,导热系数逐渐增大。在添加量为5%时,复合相变材料的融化和凝固潜热比纯石蜡相对减小了15.5%和13.8%;固态和液态导热系数比纯石蜡相对提高了39.5%和40.3%,同时具有较好的循环稳定性。4.构造了添加RT4-3%MWCNT复合相变材料的冷藏陈列柜复合搁架,对比分析了其对柜内食品包温度分布的影响。结果表明:复合搁架具有较好蓄冷性能,能有效地降低柜内食品包温度和融霜期间食品包的温度波动。相比普通搁架,RT4复合搁架上左右侧和前后排食品包温差分别减小80.0%和7.6%;RT4-3%MWCNT复合搁架上左右侧和前后排食品包温差分别减小92.0%和12.2%。论文的研究也表明添加复合相变材料能增强复合搁架的传热和提升冷藏陈列柜性能。
[Abstract]:As the end equipment of food cold chain, vertical open food refrigerated display cabinets play an important role in ensuring food quality and safety. In the process of defrosting, the temperature of the food rises to a large extent, so this paper optimizes the structure of the air curtain return tuyere, strengthens the heat transfer of the food in the cabinet, and improves the temperature uniformity of the composite shelf. Theoretical and experimental studies were carried out to reduce the recovery of food temperature during defrosting. The main contents and conclusions of this paper are as follows: 1. By adding the windshield and increasing the length of the bottom plate to overcome the cold overflow problem of the air curtain return tuyere of the refrigerated display cabinet, the results show that:. Adding the windshield and increasing the length of the bottom plate can effectively reduce the cold overflow at the air curtain return tuyere, and the temperature of the lower side food package can be reduced by 0.16 ~ 0.65K by adding the windshield. The temperature of the food package on the bottom plate can be reduced by increasing the length of the bottom plate by 0 ~ 200mm, and the food package on the bottom plate can be cooled at the same time. The experimental conditions have great influence on the thermal properties of phase change materials measured by differential scanning calorimeter (DSC). By changing the heating rate, the quality of the samples is improved. The experimental results show that the temperature and mass of the sample have great influence on the phase transition temperature and latent heat of the sample, and the influence of the flow rate of atmosphere on the temperature and latent heat of phase transition is small. In order to ensure the accuracy of the experimental results, the sample mass should be about 10.0mg and the heating rate of paraffin RT4 should be lower (鈮，

本文编号：1481518