Study on distribution characteristics of splitter plate in shell and tube evaporator

doi:10.11949/0438-1157.20210247

Abstract

Abstract:

The uneven distribution of refrigerant between the heat exchange tubes of the evaporator will result in a decrease in its refrigeration capacity. Three-dimensional models of shell and tube evaporator and splitter plates were established. The effects of splitter plate position, aperture, number and opening structure on R410A flow distribution performance were simulated. The results show that the parameters of splitter plate have a significant effect on uniform distribution of refrigerant. Under different inlet flow rate conditions, the unevenness declined with the movement of splitter plate to the inlet of evaporator, and the decrease rate gradually slowed down. The unevenness increases with the diameter of aperture, decreases with the number of opening and reaches stability. After optimizing the opening structure of the splitter plate, the average performance of the upper and lower smallhole can be increased by 21.4% compared with the equal round hole structure. The evaporator flow distribution experimental platform was built. The flow distribution law obtained from simulation and the improvement of flow evenness performance with splitter plate were verified by experiments. Which illustrate that optimizing the opening structure of splitter plate according to characteristics of flow distribution can effectively improve the effect of refrigerant evenness.

Key words: flow, numerical simulation, experimental validation, unevenness, splitter plate

摘要：

蒸发器换热管间制冷剂的分配不均会导致其制冷能力的下降。建立了管壳式蒸发器和分流板三维模型，模拟研究了分流板的位置、开孔大小、开孔数量和开孔结构对R410A均分性能的影响。模拟结果表明，分流板各参数对制冷剂均流效果有显著影响。在不同入口流速工况下，不均匀度随分流板向蒸发器入口端的移动而下降且降幅逐渐变缓；不均匀度随开孔直径的增大而上升，随开孔数量的增大而下降并达到稳定；经优化分流板开孔结构，上下小孔结构的均分性能相比等圆孔结构可提高21.4%。搭建了蒸发器流量分配实验台，通过实验验证了模拟得出的流量分配规律以及分流板对流体均分性能的提升，说明根据流量分布特点优化分流板开孔结构能有效提升制冷剂的均流效果。

关键词: 流动, 数值模拟, 实验验证, 不均匀度, 分流板

CLC Number:

TB 657

Zhe SONG, Bo XU, Zhenqian CHEN. Study on distribution characteristics of splitter plate in shell and tube evaporator[J]. CIESC Journal, 2021, 72(9): 4629-4638.

宋哲, 许波, 陈振乾. 管壳式蒸发器内分流板均分性能的研究[J]. 化工学报, 2021, 72(9): 4629-4638.

Figures/Tables 17

Table 1 Structural parameters of evaporator model

结构参数	数值
管箱内径/mm	200
管箱长度/mm	80
换热管规格/mm	15.9×0.89
换热管长度/mm	1000
换热管间距/mm	25
布管方式	正三角形
分流板孔径/mm	6
分流板孔间距/mm	10

Fig.1 Shell and tube evaporator model with radial inlet

Fig.2 Heat exchange tube number diagram

Fig.3 Opening structure of splitter plate

Table 2 Opening size of splitter plate

孔数	孔径/mm	开孔面积/mm²	孔隙率
277	4	3480.9	0.111
277	4.5	4405.5	0.140
277	5	5438.9	0.173
277	5.5	6581.0	0.210
277	6	7832.0	0.249
277	7	10660.2	0.339
277	8	13923.5	0.443
277	9	17622.0	0.561

Table 3 Hole counts on splitter plate

孔数/个	孔径/mm	开孔面积/mm²	孔隙率
277	5	5438.9	0.173
193	6	5456.9	0.174
141	7	5426.3	0.173
97	8.4	5375.5	0.171
69	10	5419.2	0.172
45	12.4	5434.3	0.173

Fig.4 Schematic diagram of experimental system

Table 4 Parameters and accuracy of measuring instruments

测量仪器	测量范围	测量精度
气体流量计	0~10 L/min	±2.0%
	0~200 L/min	±2.5%
液体流量计	0.7~7 m³/h	±1.0%
称重显示器	0~30 kg	±0.01kg
量杯	0~5000 ml	10 ml

Fig.5 Average fraction and inlet relative pressure of pipes

Fig.6 STD changes with the position of splitter plate

Fig.7 Refrigerant flow field distribution on symmetry plane

Fig.8 STD and pressure drop changed with opening diameter

Fig.9 STD and pressure drop change with hole count

Fig.10 STD and pressure drop of different opening structure

Fig.11 Average fraction of pipes and opening structures

Fig.12 Flow distribution in different distribution structures

Fig.13 Comparison of STD in different structures

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