| 摘要: |
| 本文利用数值模拟结合实验验证的方法对比了170 Pa和190 Pa两种压力条件下，3种不同结构的V型条缝喷嘴对冲击式速冻设备换热情况的影响，分别从喷嘴出口风速、横流方向风速以及努塞尔数（Nu）3个方面进行研究分析。结果表明：喷嘴延伸段长度K较大的喷嘴出口风速较大、流场较为均匀，但较大的喷嘴延伸段长度K反而会削弱对流换热的强度；喷嘴渐缩段与延伸段之间的夹角α较小的喷嘴在横流方向上的风速较小、均匀度较高，受横流影响较小，但对提高对流换热强度的作用不明显；当V型条缝喷嘴延伸段长度K=10 mm，喷嘴渐缩段与延伸段之间的夹角α=165°时，平均努塞尔数最高，对流换热的强度最大。 |
| 关键词: 冻结食品 冲击式速冻技术 计算流体力学 喷嘴结构 |
| DOI： |
| 投稿时间：2018-12-27 修订日期：2019-05-05
|
| 基金项目:国家“十三五”重点研发（2018YFD0400605），上海市教育委员会和上海市教育发展基金会“晨光计划”（16CG55）和上海海洋大学科技发展专项基金（A2-0203-17-100207）资助项目。 |
|
| Effect of Slit Nozzles of Different Structures on the Heat Transfer of Impinging Jets |
|
Shu Zhitao, Xie Jing, Yang Dazhang
|
| (Shanghai Professional Technology Service Platform on Cold Chain Equipment Performance and Energy Saving Evaluation, Shanghai Engineering Research Center of Aquatic Product Processing & Preservation, College of Food Science and Technology, Shanghai Ocean University) |
| Abstract: |
| In this study, the effects of three types of V-shaped slit nozzles of different structures on the heat transfer of impingement quick-freezing equipment under 170-Pa and 190-Pa pressure conditions are compared by both numerical simulation and experiment. The outlet wind velocity, cross flow wind velocity and Nussel number (Nu) are investigated under different conditions. The results show that the nozzle outlet with a longerK, nozzle extension length, has a higher wind speed and more uniform flow field. However, the longer K will weaken the convective heat transfer intensity. The nozzle with a smaller angle α between the nozzle shrinking and extension sections has a lower wind speed and higher uniformity in the transverse flow direction and is less affected by the transverse flow; however, it has no obvious effect on improving the convective heat transfer intensity. When the length of the K of the V-shaped slit nozzle is 10 mm and the angle α between the nozzle contraction and extension sections is 165°, the average Nussel number and the convective heat transfer intensity are at a maximum. |
| Key words: frozen food impingement quick-freezing technology computational fluid dynamics nozzle structure |
