液氮辅助制冷冻干机冷阱模拟分析及

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摘要

液氮辅助冻干机，以液氮作为冷源，通过液氮在换热器中膨胀相变吸热的制

冷方式，解决了常规压缩机制冷冻干机存在的降温速率较慢、冷阱极限温度不够

低等问题。而冷阱是冻干机设备的重要组成部分，其结构设计也是难点。冷阱通

导能力的好坏，冷阱内空间温度场的分布，直接影响水蒸气与冷阱盘管表面的碰

撞几率，影响捕水效率。

随着 CFD 技术的不断发展，其在流体内部温度场，流场的分布分析等应用日

益广泛。在进行冻干机冷阱设计过程中，若缺乏对冷阱室内气流组织的研究，很

可能设计出来的冷阱结构庞大，造价高，结构不合理，造成水汽凝结器结霜不均，

冷阱捕水能力下降。因此，本文通过采用 Fluent 模拟软件，对液氮辅助冷冻干燥

机冷阱内部温度场，流场进行模拟分析，以期为液氮冷阱的结构设计优化，提高

冷阱的捕水效能提供参考。具体工作如下：

（1）采用 Fluent 模拟软件对冷阱建立数学模型，进行网格划分，通过热力

与流体力学分析对整个冷阱模型进行边界条件设定和计算模型的选取。

（2）实验研究了间冷式和直冷式两种液氮冻干机。分别在冷阱盘管关键部

位点安装有温度传感器，在测试中对盘管温度进行监测统计，从而来反应整个冷

阱室内温度分布状况。通过 Fluent 软件分别对两种冻干机冷阱进行室内温度场数

值模拟，绘出温度分布图，并与测试中的实验数据进行对比，得到模拟温度场与

实验关键部位点监测统计数据基本上吻合。

（3）针对 Fluent 软件模拟出的液氮冻干机冷阱温度场分布图进行分析，找

出温度分布不均匀的原因，通过修改冷阱结构，添加导流板，增强蒸气扰动，从

而使温度均匀，管壁结霜均匀，以提高冷阱捕水能力。通过 Fluent 软件对修改后

的冷阱结构进行一步模拟分析，得到了冷阱最佳优化方案。

关键词：液氮冻干机冷阱数值模拟温度场

ABSTRACT

Freeze dryer cooled by liquid nitrogen, used the cold source by liquid nitrogen,and

this is through the expansion of liquid nitrogen in heat exchangers to cooling the case,

to solve the slow cooling rate of the conventional compressor refrigeration

lyophilizer,and the problem that the limit temperature of cold trap is not low enough .

The cold trap is the important component of the freezedryer equipment,and the diffcult

of structure design in the freeze dryer. The capability of the cold-traps' transport is good

and bad, it is at a uniform temperature distribution inside the cold-trap,these directly

influence the collision probability that air collides with the shell of pipe of the

cold-trap,and the vapor condensation characteristic.

As the technology of the CFD software continuous development mature, it

becomes feasible in a analysis of fluid temperature and flow field distribution. In a

actual design process,because it is the lack of the analysis of the air-flow organization

inside the cold-trap, it may design the large structures,the expensive cost and the

unreasonable structure,these cause the irregular condensation and the decrease of the

vapor condensation. As a result, by using the Fluent software in this paper, it could be

analyze the fluid temperature and flow field distribution,to restructure the cold-trap

design and enhance the capacity of water-capture. the main work of thes paper can be

concluded as follows:

(1) The fluent simulation software was used to establish the mathematical model

for the cold trap and mesh.Through heat and fluid dynamics analysis,the model of cold

trap is to set the control equation,and to choose the computation module.

(2) Experiment have two kinds of lyophilizers with the liquid nitrogen, including

the direct and indirect cooling freeze dryer with liquid nitrogen, installing the

temperature pickup on the key parts of the pipe coil of the cold trap，

monitoring the coil

temperature in the test, to show the temperature distribution of the cold trap. The fluent

simulation software was used to simulate the temperature distribution of the cold trap of

two Freezedryers, and to compare with the experimental data from the test, in order to

let the result data of numerical simulation coincide with the result data of the

experimental test basically.

(3) From analyzing the temperature distribution of the cold trap,this paper is to find

the cause of the nonuniform temperature of the cold trap, and to modifying the structure

of the cold trap and add the guide plate,to enhance steam disturbance, the uniform frost

of the pipe wall,to enhance the capacity of water-capture eventually. At last, the fluent

simulation software was used to simulate modified structure of cold trap and analyze,to

find the best optimization scheme.

Key Words: Liquid Nitrogen, Freezedryer, Cold-trap, Numerical

simulation, Temperature field

中文摘要

ABSTRACT

第一章绪论 ...................................................................................................................1

§1.1 本课题研究的背景及意义 ................................................................................... 1

§1.2 真空冷冻干燥原理 ............................................................................................... 2

§1.2.1 真空冷冻干燥原理 .........................................................................................2

§1.2.2 真空冷冻干燥技术的应用 .............................................................................3

§1.3 真空冷冻干燥技术研究进展 .............................................................................. 4

§1.3.1 国外真空冷冻干燥技术研究进展 .................................................................4

§1.3.2 国内真空冷冻干燥技术研究进展 .................................................................5

§1.3.3 冻干机冷阱壁面结霜问题研究 .....................................................................6

§1.3.4 冻干机冷阱模拟的研究进展 .........................................................................7

§1.4 本课题的主要研究内容 ...................................................................................... 8

第二章数值模拟的理论基础与方法 .............................................................................9

§2.1 数值模拟的理论基础 ........................................................................................... 9

§2.1.1 数值模拟的研究进展 .....................................................................................9

§2.1.2.湍流的数值模拟方法 ...................................................................................10

§2.1.3 流体与流动的基本特性 ...............................................................................16

§2.2 数值模型建立方法 ............................................................................................. 17

§2.2.1 物理模型建立及其假设 ...............................................................................17

§2.2.2 控制方程相关方法 .......................................................................................17

§2.2.3 边界条件相关建议 .......................................................................................19

§2.2.4 网格单元的划分 ...........................................................................................20

§2.2.5 Fluent 模拟求解流程 ................................................................................... 21

§2.3 本章小结 ............................................................................................................ 22

第三章液氮辅助冻干机结构设计 .............................................................................23

§3.1 液氮冻干机国内外研究进展 ............................................................................. 23

§3.2 液氮冻干机结构设计与分析 ............................................................................. 23

§3.2.1 冻干箱 ...........................................................................................................24

§3.2.2 冷阱 ...............................................................................................................25

§3.2.3 真空系统 .......................................................................................................26

§3.2.4 液压压塞系统 ...............................................................................................27

§3.2.5 在位清洗（CIP）及灭菌(SIP)系统 ............................................................27

§3.2.6 液氮制冷、循环系统 ...................................................................................28

§3.3 液氮冻干工艺流程 ............................................................................................. 29

§3.4 液氮冻干机优点及应用 ..................................................................................... 30

§3.5 本章小节 ............................................................................................................ 31

第四章液氮辅助冻干机冷阱模拟分析及优化 ...........................................................32

§4.1 间冷式液氮辅助冻干机冷阱温度场模拟分析 ................................................ 32

§4.1.1 间冷式冻干机冷阱几何模型 .......................................................................32

§4.1.2 数学模型建立 ...............................................................................................33

§4.1.3 边界条件的设定 ...........................................................................................34

§4.1.4 数值模拟操作步骤 .......................................................................................34

§4.1.5 模拟结果分析及优化 ...................................................................................35

§4.2 直冷式液氮辅助冻干机冷阱温度场模拟分析 ................................................ 38

§4.2.1 直冷式冻干机冷阱几何模型 .......................................................................38

§4.2.2 数学模型 .......................................................................................................40

§4.2.3 边界条件的设定 ...........................................................................................42

§4.2.4 数值模拟操作步骤 .......................................................................................42

§4.2.5 模拟结果分析及优化 ...................................................................................43

§4.3 本章小结 ............................................................................................................ 47

第五章液氮辅助冻干机冷阱改进模拟分析 ...............................................................49

§5.1 间冷式液氮辅助冻干机改进冷阱温度场模拟分析 ......................................... 49

§5.1.1 优化间冷式液氮辅助冻干机冷阱结构 .......................................................49

§5.1.2 改进前后温度分布对比 ...............................................................................50

§5.2 直冷式液氮辅助冻干机改进冷阱温度场模拟分析 ......................................... 52

§5.2.1 优化直冷式液氮辅助冻干机冷阱结构 .......................................................52

§5.2.2 改进前后温度分布对比 ...............................................................................53

§5.3 本章小结 ............................................................................................................ 56

第六章结论与展望 .......................................................................................................57

§6.1 主要结论 ............................................................................................................ 57

§6.2 进一步研究建议 ................................................................................................ 58

参考文献 .........................................................................................................................59

在读期间公开发表的论文和承担科研项目及取得成果 .............................................63

致谢 .................................................................................................................................64

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摘要：

摘要液氮辅助冻干机，以液氮作为冷源，通过液氮在换热器中膨胀相变吸热的制冷方式，解决了常规压缩机制冷冻干机存在的降温速率较慢、冷阱极限温度不够低等问题。而冷阱是冻干机设备的重要组成部分，其结构设计也是难点。冷阱通导能力的好坏，冷阱内空间温度场的分布，直接影响水蒸气与冷阱盘管表面的碰撞几率，影响捕水效率。随着CFD技术的不断发展，其在流体内部温度场，流场的分布分析等应用日益广泛。在进行冻干机冷阱设计过程中，若缺乏对冷阱室内气流组织的研究，很可能设计出来的冷阱结构庞大，造价高，结构不合理，造成水汽凝结器结霜不均，冷阱捕水能力下降。因此，本文通过采用Fluent模拟软件，对液氮辅助冷冻干燥机冷阱内部温...

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