發(fā)布時間：2018-02-01 09:25

  本文關鍵詞： 冷藏陳列柜 復合相變材料 多壁碳納米管 強化傳熱 復合擱架 食品包　出處：《鄭州輕工業(yè)學院》2017年碩士論文　論文類型：學位論文

【摘要】：立式敞開式食品冷藏陳列柜作為食品冷鏈的末端設備,對保證食品品質(zhì)和安全起到重要作用。但其普遍存在柜內(nèi)風幕冷量外溢、柜內(nèi)溫度分布不均、融霜過程中食品溫度回升較大等缺點,因此本文從優(yōu)化風幕回風口結(jié)構(gòu)、強化柜內(nèi)食品傳熱、改善復合擱架溫度均勻性、減少融霜期間食品溫度回升等方面開展理論與實驗研究,本文主要研究內(nèi)容和結(jié)論如下:1.通過添加擋風板和增加底板長度來克服冷藏陳列柜風幕回風口冷量外溢問題。結(jié)果表明:添加擋風板和增加底板長度能有效減小風幕回風口處的冷量外溢。添加擋風板使下側(cè)食品包溫度可以減小0.16~0.65K;底板長度增加0~200mm可以降低底板上食品包溫度,同時可冷卻底板上增加的食品包,保證其滿足冷藏溫度要求。2.實驗條件對差示掃描量熱儀測試相變材料熱物性有較大影響,通過改變升溫速率、樣品質(zhì)量、氣氛流量等實驗條件對其進行了實驗研究。結(jié)果表明:升溫速率和樣品質(zhì)量對樣品相變溫度和相變潛熱影響較大,氣氛流量對其影響較小,為了保證實驗結(jié)果準確性,樣品質(zhì)量應在10.0mg左右,并采用較低(≤5K/min)的升溫速率。3.為提高石蠟RT4的導熱性能,制備了六種多壁碳納米管添加量的復合相變材料,并對其熱物性及穩(wěn)定性進行實驗研究。結(jié)果表明:隨著多壁碳納米管添加量的增加,復合相變材料的相變溫度基本不變,相變潛熱逐漸減小,導熱系數(shù)逐漸增大。在添加量為5%時,復合相變材料的融化和凝固潛熱比純石蠟相對減小了15.5%和13.8%;固態(tài)和液態(tài)導熱系數(shù)比純石蠟相對提高了39.5%和40.3%,同時具有較好的循環(huán)穩(wěn)定性。4.構(gòu)造了添加RT4-3%MWCNT復合相變材料的冷藏陳列柜復合擱架,對比分析了其對柜內(nèi)食品包溫度分布的影響。結(jié)果表明:復合擱架具有較好蓄冷性能,能有效地降低柜內(nèi)食品包溫度和融霜期間食品包的溫度波動。相比普通擱架,RT4復合擱架上左右側(cè)和前后排食品包溫差分別減小80.0%和7.6%;RT4-3%MWCNT復合擱架上左右側(cè)和前后排食品包溫差分別減小92.0%和12.2%。論文的研究也表明添加復合相變材料能增強復合擱架的傳熱和提升冷藏陳列柜性能。
[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，

本文編號：1481518