论文总字数：23648字

摘 要

当前果蔬大规模化的种植的前提下，果蔬的干制加工产业，不仅可提高蔬菜的附加值，还能解决果蔬保存问题。但是，由于我国国内干制果蔬加工方式以及设备都存在问题，冷却时间过程过长，加热不均，缺乏实时监控的问题，导致干制果蔬的质量整体不是很理想。本课题根据果干加工膨化过程后期对快速冷却性能的要求而提出的题目。针对果蔬干燥膨化后期果蔬品质以及生产效率受到冷却速率的影响的问题，我们将对果蔬加工工艺流程进行改善，并采用热管传热元件，对设备加以改进。分析了果蔬干燥冷却过程、干燥冷却原理和热质传递特性。本文进行5 kg果蔬干燥冷却热量和果干切片表面积的计算，确定系统干燥冷却温度和压力的工作范围，选定相应的热管结构，进行热管结构设计和内部传热能力校核，进行了热管内外径、热段长度、根数、加热段换热面积、冷却换热面积、热管冷却时间的计算。研究设计如下：

1. 选定5kg苹果，其含水量为60%，作为研究对象，介绍了原苹果干燥工艺流程，重新分布各阶段的水分析出量。
2. 计算了各阶段的吸热量，选定吸液芯热管作为加热以及冷却阶段的换热设备，并根据要求设计和校核了热管的结构。
3. 我在冷却阶段运用了减压冷却技术，在真空泵的连续抽吸形成了低压的情况下，果干温度迅速降低至34℃，用时仅为1.2小时。
4. 后期通过热管冷却技术，算出了热管对空气的换热系数，果干对空气的换热系数，以及热管传热功率，将果干从34℃降低至20℃，用时45分钟。
5. 通过以上两种方式，冷却时间大大缩短，由原有的4-6小时缩短为2-3小时，生产效率大大提高。

关键词：果蔬干制 冷却技术 翅片热管

Research and design of fast cooler for 5kg fruit and vegetable processing

Abstract

The task was put forward according to the performance requirements of rapid cooling of dried fruit during later processing and expanding process.In view of the problem of the effect of cooling rate on fruit and vegetable quality and production efficiency in the late stage of fruit and vegetable processing and expanding process,We will improve the processing technology of fruit and vegetable processing and use the heat pipe heat transfer element to improve the equipment.We can master the cooling process of fruit and vegetable drying and drying cooling principle and heat and mass transfer characteristics from it.This paper calculates the heat of cooling and drying of 5 kg fruits and vegetables and dried fruit slice surface area.We will determine the operating range of the system's dry cooling temperature and pressure and chose the corresponding heat pipe structure ,and the heat pipe structure design and check the internal heat transfer capability.Then,we caculate the internal and external diameter of the heat pipe, the length of the pipe and cold section, the number of the heat pipes, the heat exchange area of the heating section, the calculation of the cooling heat exchange area, and the cooling time of the heat pipe .Improved design is as follows：

（1） 5kg of apples, its water content was 60%, as the research object, introduced the original apple drying process and re arrangement the amount of water analysis in each stage .

（2） The heat absorption capacity of the various stages and wick heat tube has been selected as heating and cooling stage of heat transfer equipment, and I design and check the structure of the heat pipe according to the requirement.

（3） Pressure reducing technology in cooling stage has been used in this paper.With continuous suction of the vacuum pump,low pressure is formed.The temperature of Dried fruit rapidly reduce to 34℃.The time of this stage is about 1hours.

（4） Combined with the heat pipe cooling technology, heat transfer coefficient of the heat pipe to the air is calculated, the heat transfer coefficient between air and dried fruit and heat transfer power of heat pipe.The temperature of Dried fruit rapidly reduce to 20℃.The time of this stage is about 45 minutes.

（5） Through the above two ways, the cooling time is greatly shortened. The initial time of cooling stage changes into 2-3 hours.The production efficiency is greatly improved.

Key Words: Fruit and vegetable drying system Finned heat pipe Cooler

目 录

摘要…………………………………………………………………………………… I

ABSTRACT ……………………………………………………………………… II

第一章 绪论 ……………………………………………………………………… 1

1.1 背景 ………………………………………………………………………… 1

1.1.1 干制果蔬发展历史景 ………………………………………………… 1

1.1.2 干制果蔬加工技术背景 ……………………………………………… 1

1.2 果蔬干制加工流程、设备及技术 ………………………………………… 1

1.2.1 果蔬干制加工流程 …………………………………………………… 1

1.2.2 果蔬干燥加工设备 …………………………………………………… 2

1.2.3 果蔬干燥技术 ………………………………………………………… 3

1.3 果蔬品质影响因素 ………………………………………………………… 4

1.4 冷却技术及换热元件介绍 ………………………………………………… 5

1.4.1 冷却方式分类 ………………………………………………………… 5

1.4.2 冷却换热元件介绍 …………………………………………………… 5

1.4.3 热管的多种型式 ……………………………………………………… 6

1.5 国内外冷却技术以及热管研究状况 ……………………………………… 9

1.5.1冷却技术研究现状 …………………………………………………… 9

1.5.2热管的研究现状 ……………………………………………………… 10

1.6 果蔬加工冷却未来发展 …………………………………………………… 10

1.7 课题来源 …………………………………………………………………… 11

1.8 研究思路和技术方法 ……………………………………………………… 11

第二章 工艺流程描述…………………………………………………………… 13

2.1 原果蔬干制加工流程及存在问题 ………………………………………… 13

2.1.1 原加工设备描述 ……………………………………………………… 13

2.1.2 果蔬干制加工干燥步骤 ……………………………………………… 13

2.1.3 果蔬干燥膨化后期冷却存在问题 …………………………………… 13

2.2 果蔬干燥工艺过程改善 …………………………………………………… 14

2.2.1 改进后换热设备的描述 ……………………………………………… 14

2.2.2 果蔬干燥工艺改良步骤 ……………………………………………… 14

第三章 热力计算及换热设备选取 …………………………………………… 15

3.1 各阶段果蔬传热传质热力计算与传热时间计算 ………………………… 15

3.1.1加热阶段的热力计算 ………………………………………………… 15

3.1.2热管结构型式选取及热力校核 ……………………………………… 16

3.2 减压冷却过程热管传热传质热量及时间计算 …………………………… 22

3.2.1减压冷却过程传热传质计算 ………………………………………… 22

3.2.2后期冷却过程传热过程及时间计算 ………………………………… 25

第四章 结论与展望 ……………………………………………………………… 27

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