论文总字数：18935字

摘 要

果蔬是人们的食物中不可或缺的，它含有丰富的营养成分，对人们的身体健康有很重要的作用。我国的果蔬资源丰富，果蔬产业发展迅速。但是,果蔬中含有的很多水分，这导致果蔬在储存、运输等方面很麻烦，稍有不慎就会造成巨大损失。而传统的干燥过程由于脱水的温度高而且时间长，会破坏果蔬内部的营养和组织结构且生产效率较低，而高品质的生产设备往往价格过高，导致性价比不乐观。因此，干燥果蔬的研究势在必行，这对果蔬行业的发展有很重要的作用。

本课题研究用100℃水蒸气作为热源的热管加热干燥苹果片。首先，介绍了原干燥过程并对原干燥过程进行了改进。然后，设计了翅片热管的各种尺寸参数和苹果切片之后的各种参数。之后，计算了热管在加热加压和膨化过程中的各种参数并对这两个过程中的能量传递进行了分析计算。最后，使用Gmabit和Fluent软件对干燥过程进行建模及模拟，得出温度场分布图。

本课题得出在1.4MPa压力下，在41分钟内，苹果片失去0.268kg左右水分。当罐内压力由1.4MPa降低到0.02MPa，热蒸汽瞬间膨化蒸发，苹果片中散出3.572kg水分，体积膨胀。

关键词： 果蔬干燥 热管 换热系数 模拟

Analysis and Simulation of heat and mass transfer process in the heating and drying of fruits and vegetables

ABSTRACT

Fruits and vegetables are an integral part of people's food, it contains rich nutrients and has very important effects on people's physical health. Our country is rich in fruits and vegetables, and the fruit and vegetable industry is developing rapidly. However, it contains a lot of water, which leads to fruits and vegetables during storage and transportation is very troublesome, the slightest mistake will cause huge losses. Because of high dehydration temperature and the long time. It will destroy the nutritional and organizational structure of the fruits and vegetables, and the production efficiency is low. And because high quality production equipment is usually high price, leading to the price is not optimistic. Because of this, it is necessary to study the drying of fruits and vegetables, which has a very important role in the development of the fruit and vegetable industry.

In this research, we use 100 water vapor as the heat source to heat the tube to heat the dried apple slices. First of all, this paper introduces the original drying process and improves the original drying process. Then, various parameters of fin heat pipe and various parameters of apple slices were designed. After that, the parameters of the heat pipe in the process of heating and pressure were calculated, and the energy transfer in these two processes was calculated. Finally, the drying process is modeled and simulated by using Gmabit and Fluent, and the distribution of temperature field is obtained.

The subject that in 1.4Mpa under pressure. In 41 minutes. Slice of Apple lost about 0.268kg water. When tank pressure by 1.4Mpa reduced to 0.02MPa. Heat instant steam puffing evaporation, apple slices in shed water 3.572kg, volume expansion. In 1.4Mpa pressure

Key words: Fruit and vegetable; Drying heat pipe; Heat transfer; Coefficient simulation

目录

摘要……………………………………………………………………………………………Ⅰ

Abstract………………………………………………………………………………………Ⅱ

第一章 绪论…………………………………………………………………………………1

1.1 背景意义…………………………………………………………………………1

1.2 现有技术……………………………………………………………………………1

1.2.1 微波干燥技术…………………………………………………………………2

1.2.2 远红外干燥技术………………………………………………………………2

1.2.3 真空冷冻干燥技术……………………………………………………………2

1.2.4 联合干燥技术…………………………………………………………………2

1.3 热管概况及研究现状………………………………………………………………2

1.3.1热管元件的结构及工作原理…………………………………………………2

1.3.2 热管种类及分类………………………………………………………………4

1.4传热传质过程模拟软件及方法简介…………………………………………………6

1.5 国内外研究状况……………………………………………………………………6

1.6 课题研究内容及步骤………………………………………………………………8

第二章 干燥工艺分析及计算……………………………………………………………9

2.1 原工艺的缺点和改进方法…………………………………………………………9

2.1.1 原干燥工艺过程………………………………………………………………9

2.1.2 改进后苹果片干燥过程具体工艺流程………………………………………9

2.2 初始工艺参数确定…………………………………………………………………10

2.2.1 干燥罐参数………………………………………………………………………10

2.2.2 苹果片参数…………………………………………………………………10

2.3 热管与翅片设计……………………………………………………………………11

2.3.1 热管内工作液体的选择……………………………………………………11

2.3.2 壳体材料的选择及强度计算………………………………………………12

2.3.3 翅片选择……………………………………………………………………13

2.4 热管的换热系数确定………………………………………………………………13

2.4.1 加热加压过程…………………………………………………………………13

2.4.2 膨化过程………………………………………………………………………14

2.5 加热加压过程热管壁面换热计算…………………………………………………15

2.6 加热加压过程分析…………………………………………………………………16

2.7 膨化过程的分析……………………………………………………………………17

第三章 建模及模拟……………………………………………………………19

3.1 Gambit软件建模……………………………………………………………………19

3.2 Fluent软件温度场模拟……………………………………………………………20

第四章 结论与未来展望………………………………………………………………23

4.1 结论………………………………………………………………………………23

4.2 未来展望…………………………………………………………………………23

参考文献……………………………………………………………………………………24

致谢…………………………………………………………………………………………26

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