论文总字数：26164字

摘 要

我国的果蔬种类非常丰富、资源也多、而且果蔬质量优良、价格也较低。果蔬中含有大量无机盐、碳水化合物以及人体所需的微量元素，因此果蔬我们日常食物的重要来源和必不可少的食物。

本课题研究的意义是新鲜的果蔬由于季节性强，不宜存放，且生产地一般远离城市，运输经费高，在运输途中会出现水果磕碰，损坏，变质腐烂等情况，因此将新鲜果蔬脱水干制逐渐成为商家加工果蔬的一种主要方式。

果蔬干燥过程是通过干燥物与果蔬之间发生热质交换的过程，干燥物通过果蔬表面把热量传递到果蔬内部，果蔬的水分通过果蔬表面传递到物体外，使果蔬变干。干燥物和湿物之间的温度差，是水从果蔬内部扩散果蔬外部环境的主要动力。

由于在干燥过程中温度场的不均匀导致果蔬的品质受到很大的影响。本课题通过研究5kg苹果的干燥过程找出果蔬干燥过程中导致温度场不均匀的原因，经过分析，苹果在加热加压阶段的所扩散出来的水分为0.43kg，因为当蒸汽达到饱和压力时，继续给苹果提供热量也无法使果蔬中的水分析出。干燥器内部的温度场可以通过fluent模拟软件进行模拟，在用fluent软件模拟前需要用Gambit进行建模，模型包括蒸汽管道的排布和果蔬的排布。建模完成后需要对模型设置边界条件以及相应的冷源和热源，即苹果片和空气为冷源，蒸汽管壁为容器内壁为热源。

用fluent模拟软件模拟模拟的结果显示，苹果片的排列方式的不同、蒸汽管道的排列方式的不同以及热源温度不同均会导致苹果片干燥器内部温度场的不同，所以，经过多次模拟的出热源温度为100℃时 ,蒸汽管道为20根的时候干燥容内部的温度场最均匀。

关键词：果蔬干燥；模拟；温度场

Analysis and Simulation of the drying process

of fruits and vegetable

abstract

China's fruits and vegetables are very rich in species, resources are also more, and the quality of fruits and vegetables is good, the price is low. Fruits and vegetables contain a large number of inorganic salts, carbohydrates and trace elements needed by the human body, so the important source of our daily food and essential food.

The significance of this study is the fresh of the fruits and vegetables because of the strong seasonal, should not be stored, and production is usually far from the city, transportation funding, in transit will appear fruit bump, damage, rot and so on. Therefore, the fresh fruit and vegetable dehydration gradually become a main mode of business and industry and trade of fruits and vegetables.

In the drying process of fruit and vegetables is the heat and mass transfer process between the dry matter of fruit and vegetable, dry matter through the surface of fruits and vegetables to transfer heat to fruits and vegetables, fruits and vegetables in water through the surface of the fruit and vegetable transfer to the outside of the object, so that the fruits and vegetables dry. The temperature difference between the dry and wet things is the main driving force of the water diffusion from fruits and vegetables.

The quality of fruits and vegetables is greatly affected by the uneven temperature field during the drying process. This topic through the drying process of Apple 5kg research found in the drying process of fruit and vegetables lead to cause uneven temperature field. After analysis, the apple in the heating pressurization phase of the spread out of the water for 0.43kg, because when the steam saturation pressure is reached, continue to provide heat to the Apple could not make fruits and vegetables in water analysis. Inside the dryer temperature field was simulated by fluent simulation software, before the use of FLUENT software simulation to gambit is used for the modeling. The model includes the arrangement of the steam pipe arrangement and fruits and vegetables. After modeling, the boundary condition of the model is set and the corresponding cooling source and heat source are set, that is, the apple slices and air are cold source, the steam pipe wall is the heat source of the inner wall of the container.

With fluent simulation software to simulate the results of the simulations show, different arrangement of apple slices, steam pipe arrangement and different heat source temperature will lead to Apple chip dryer interior temperature field is different, so after many simulation the the heat source temperature is 100 DEG C, steam pipe for 20 root dry internal temperature distribution is most uniform.

Keyword ：Fruit and vegetable drying; simulation; temperature field.

目录

摘要.................................................................................................................................ǀ

Abstract...........................................................................................................................ǁ

1. 绪论..................................................................................................................1

1.1我国果蔬存在的一些问题..............................................................................1

1.2果蔬干燥原理..................................................................................................1

1.3果蔬干燥技术..................................................................................................1

1.3.1真空干燥技术.........................................................................................1

1.3.2微波－热风联合干燥.............................................................................2

1.3.3冷冻－热风联合干燥.............................................................................2

1.3.4渗透脱水－热风联合干燥.....................................................................2

1.3.5低压过热蒸汽－远红外联合干燥.........................................................3

1.3.6热泵－热风联合干燥.............................................................................3

1.3.7微波真空－热风联合干燥.....................................................................3

1.3.8微波真空干燥.........................................................................................3

1.3.9热管干燥技术.........................................................................................4

1.4 果蔬干燥国内外研究现状.............................................................................5

1.5果蔬干燥传热传质过程的分析......................................................................5

1.5.1果蔬内部的传热传质过程.....................................................................6

1.5.2果蔬内部的传质过程..............................................................................6

1.6.果蔬干燥过程的热质传递模型及模拟..........................................................6

1.6.1建立模拟物理模型..................................................................................6

1.6.2 热质传递模拟模型.................................................................................7

1.6.3 边界条件................................................................................................7

1.6.4 模拟模型的求解....................................................................................8

1.7果蔬品质的影响因素.......................................................................................8

1.8Fluent模拟软件的介绍.....................................................................................9

1.8.1Fluent软件的模块组成....................................................................9

1.8.2FLUENT软件的优点............................................................................10

1.9结论................................................................................................................10

第二章 果蔬干燥的热力计算....................................................................................11

2.1原干燥设备工艺过程....................................................................................11

2.2果蔬干燥膨化工艺过程分析及参数确定....................................................11

2.3苹果的表面积................................................................................................12

2.4果蔬加压干燥阶段的热力分析及计算........................................................12

2.4.1干燥过程需求热量的计算.....................................................................12

2.4.2加热饱和水蒸气的流量计算.................................................................14

2.4.3蒸汽加热式容器壁内部传热分析.........................................................14

2.4.4厚度的计算强度校核.............................................................................16

2.4.5内部蒸汽加热管的传热分析.................................................................17

请支付后下载全文，论文总字数：26164字