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云计算-CO2冷风机性能理论计算和实验研究.pdf
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云计算-CO2冷风机性能理论计算和实验研究.pdf
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II
对比中,理论计算值和实验值的最大误差为 25%左右,最小误差为 14.8%。
关键词:
CO
2
冷风机;静压箱;迎面风速;换热性能;
万方数据
III
ABSTRACT
Today, all of the word are facing the more and more environmental problems, such as
ozone hole and greenhouse effect. Refrigeration industry has an unshakable responsibility.
From the Montreal Protocol to the present Montreal Protocol-Kigali amendment, are
continuing to promote the use of environmentally friendly and efficient refrigerants. CO
2
,
as the earliest natural refrigerant, accessed by the refrigeration industry after abandoned
about hundred years. Although as refrigerant, CO
2
still has some technical problems, but its
superior environmental performance, thermal performance and low price makes it has a
very large space for development in the modern refrigeration industry. Air-cooler is the
most commonly used and most critical components in cold storage and other refrigeration
systems. Improving the performance of air-cooler has a significant effect on the
optimization and energy saving of refrigeration systems.
In this paper, the effect of geometrical parameters, air side parameters and the
refrigerant side parameters on the performance of the air-cooler are analyzed by theoretical
calculation and experimental study. The concrete research are as follows.
(1) According to the geometric structure and size of the CO
2
air-cooler, the steady - state
partitioning parameter model is established by referring to the empirical formula in the
relevant literature. Before the mathematic model is established, some factors that have little
effect on the calculation result are neglected, and the calculation model is more simple and
convenient.
(2) The heat transfer coefficient and the cooling capacity of the CO
2
air-cooler were
calculated by the mathematical model under different structural geometrical parameters,
different air side parameters and different refrigerant side parameters. The influence of the
geometric parameters of the air-cooler on its heat transfer coefficient and cooling capacity
is shown below. The heat transfer coefficient is proportional to the fin spacing and is
inversely proportional to the tube spacing. On the contrary, the cooling capacity is inversely
proportional to the fin spacing and proportional to the tube spacing. The influence of the air
side parameters on the chillers is as follows. Heat transfer coefficient and cooling capacity
are proportional to the temperature of the calibration tank; there is the best face velocity
(3.2-3.4 m/s) to make the performance of air-cooler to best. The influence of the refrigerant
side parameters on the air-cooler is as follows, the heat transfer coefficient of the air-cooler
is proportional to the circulation rate, and the best circulation rate is about three. In practical
application, it should be a comprehensive consideration of these factors, so that the effect of
the air-cooler to achieve the best.
(3) The influence of the plenum chamber width on the wind speed uniformity of the
windward and the influence of the plenum chamber width on the heat transfer coefficient of
万方数据
IV
the air-cooler were studied experimentally. The results show that when the plenum chamber
width changes from 320mm to 520mm, the wind speed uniformity of windward is getting
higher and higher. As the plenum chamber width reaching 520mm, the maximum wind
speed and the minimum wind speed difference is only 0.11m / s. The heat transfer
coefficient is proportional to the plenum chamber width. When the plenum chamber width
is 520mm and the calibration tank temperature is -20 ℃ , the heat transfer coefficient is
15.8W / m
2
• K.
(4) The experimental study on the performance of No. 1 air-cooler is studied
experimentally under different air side parameters and refrigerant side parameters. And the
experiment has the same trend with the theoretical calculation, the experimental data show
that the heat transfer coefficient and cooling capacity of air-cooler is proportional to the
calibration tank temperature. When the temperature of the calibration box is in the range of
-40 to -20℃, the variation range of the corresponding heat transfer coefficient is 14.9 to
16.5 W / m
2
• K, the cooling capacity variation range is 30.4-32.6kW, increase of 10.7%
and 7.2% respectively. When the circulation rate is changed and reaches 3, the value of the
heat transfer coefficient tends to be stable.
(5) Comparing the experimental value and the theoretical calculation value of the No. 1
air-cooler, verify the rationality of the mathematical model. The results show that the trend
of the experimental value and the theoretical calculation are consistent basically, the
theoretical calculation value is higher than the experimental value. In each comparison, the
maximum error value of the theoretical calculation and the experimental are about 25%, the
minimum error is 14.8%.
Key words:CO
2
Air-cooler,Plenum Chamber,Face Velocity,Heat Exchange Performance
万方数据
目录
摘要
..........................................................................................................................................
I
ABSTRACT
...........................................................................................................................
III
第一章绪论
.............................................................................................................................
1
1.1 课题研究背景及意义
......................................................................................................
1
1.2
国内外研究现状
..............................................................................................................
2
1.2.1 CO
2
作为制冷剂的研究现状
........................................................................................
2
1.2.2
冷风机的研究现状
.......................................................................................................
6
1.2.3 数值模拟的研究现状
...................................................................................................
8
1.3 本课题的研究内容
..........................................................................................................
9
1.4 本章小结
..........................................................................................................................
9
第二章冷风机仿真模型的建立
...........................................................................................
10
2.1 物理模型的建立
............................................................................................................
10
2.2
仿真模型的假设
............................................................................................................
10
2.3
模型控制单元的划分
....................................................................................................
10
2.4
冷风机换热计算
............................................................................................................
11
2.4.1 管外空气换热计算
.....................................................................................................
11
2.4.2 管内制冷剂换热计算
..................................................................................................
15
2.4.3 冷风机总传热系数的计算
.........................................................................................
17
2.5
冷风机流动阻力计算
....................................................................................................
18
2.5.1
空气侧流动阻力计算
.................................................................................................
18
2.5.2
制冷剂侧流动阻力计算
.............................................................................................
19
2.6 计算流程图
....................................................................................................................
21
2.7 本章小结
........................................................................................................................
22
第三章 CO
2
冷风机实验台介绍
.......................................................................................
23
3.1 实验台搭建的意义
........................................................................................................
23
3.2 实验台介绍
....................................................................................................................
23
3.3
冷风机制冷量的测试方法
............................................................................................
31
万方数据
3.3.1 空气侧热平衡法
.........................................................................................................
32
3.3.2 制冷剂侧焓差法
.........................................................................................................
32
3.4
实验测试工况
................................................................................................................
33
3.5
本章小结
.........................................................................................................................
34
第四章数值计算结果分析
...................................................................................................
35
4.1
空气侧参数对冷风机换热系数的影响
........................................................................
35
4.1.1
校准箱温度对传热系数及制冷量的影响
.................................................................
35
4.1.2 迎风面风速对传热系数及制冷量的影响
.................................................................
36
4.2 冷风机几何参数对冷风机换热系数的影响
................................................................
37
4.2.1 翅片间距对换热系数的影响
.....................................................................................
37
4.2.2
管间距对换热系数的影响
.........................................................................................
38
4.3
循环倍率对冷风机换热系数的影响
............................................................................
39
4.4
本章小结
........................................................................................................................
39
第五章实验结果分析
...........................................................................................................
41
5.1
Ⅰ号冷风机静压箱宽度对冷风机性能的影响
............................................................
41
5.1.1 Ⅰ号冷风机静压箱宽度对迎风面风速均匀性的影响
.............................................
41
5.1.2 Ⅰ号冷风机静压箱宽度对冷风机换热系数的影响
.................................................
43
5.2 Ⅰ号冷风机空气侧及制冷剂侧参数对其性能的影响
................................................
44
5.2.1
空气侧参数对冷风机性能影响
.................................................................................
44
5.2.2
制冷剂侧参数对冷风机传热系数的影响
.................................................................
45
5.3
三台冷风机的对比
........................................................................................................
47
5.3.1 Ⅰ号冷风机和Ⅱ号冷风机的对比
.............................................................................
47
5.3.2 Ⅰ号冷风机和Ⅲ号冷风机的对比
.............................................................................
47
5.4 Ⅰ号冷风机实验值与计算值的对比
............................................................................
48
5.4.1
迎风面风速影响规律理论值与实验值的对比
.........................................................
49
5.4.2
循环倍率影响规律理论计算值和实验值的对比
.....................................................
49
5.4.3
校准箱温度影响规律理论值与实验值对比
.............................................................
50
5.5 本章小结
........................................................................................................................
51
第六章结论及展望
...............................................................................................................
52
万方数据
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