固体冷表面上液滴凝结过程分析

doi:10.16085/j.issn.1000-6613.2020-2118

摘要/Abstract

摘要：

液滴凝结的换热方式在航空航天工程、蒸汽动力工程、化学工程等工业领域有着广泛应用，滴状凝结更利于强化换热，大多研究专注于单个液滴凝结过程的研究，本文对液滴凝结群的性状特征进行研究，通过可视化的试验设备观察四氟乙烯平板冷表面上的液滴凝结过程，探究在不同过冷度以及相对湿度情况下冷表面上液滴凝结过程的变化规律。试验结果表明：相对湿度较过冷度来看对液滴凝结速率影响最大；第1代液滴数量随凝结时间呈正态分布，不同过冷度下液滴数量峰值出现时间为180~480s，均集中在1.0×10¹²~1.6×10¹²区间，高相对湿度下液滴合并时间短，更快进入第2代液滴凝结过程；第2代液滴形成过程中，不同相对湿度下高过冷度液滴数量峰值均高于低过冷度，80%RH时过冷度24K是22K的近2倍；面积率峰值均集中在75%~82%区间，稳定后面积率在65%~85%之间波动。在工程实际中在对液滴状态特定需求下进行环境条件的选取以及对应环境条件下对液滴特性的预测判断具有指导意义，提高冷凝换热设备的换热性能对节约能源、原材料和保护环境等方面具有积极意义。

关键词: 液滴, 凝结过程, 凝结数量, 面积率, 四氟乙烯, 传热

Abstract:

Droplet condensation heat transfer mode in industry such as aerospace engineering, steam power engineering, chemical engineering has wide application. The individual droplet condensation process has been largely studied. The characteristics of droplet condensation group were studied in this paper. The condensation process of droplet on the cold surface of tetrafluoroethylene plate was observed by visual experimental equipment, and the change rule of droplet condensation process on the cold surface was explored under different conditions of subcooling degree and RH (relative humidity). The experimental results show that RH has the greatest influence on droplet condensation rate compared with subcooling degree. The number of droplets in the first generation was normally distributed with the setting time. The peak time of droplets in different subcooling degrees was 180—480s, and they were all concentrated in the range of 1.0×10¹²—1.6×10¹². Under high RH, the droplet consolidation time is shorter and the second generation droplet condensation process is faster. During the formation of the second generation of droplets, the peak value of the number of droplets with high subcooling degree under different RH was higher than that with low subcooling degree. The subcooling degree of 24K at 80%RH was nearly 2 times that of 22K. The peak values of the area rate were all concentrated in the range of 75%—82%, and the area rate fluctuated between 65%—85% after stabilization. In engineering practice, it is of guiding significance to select environmental conditions under specific requirements of droplet state and to predict and judge droplet characteristics under corresponding environmental conditions. Improving the heat exchange performance of condensing and heat exchange equipment has positive significance for energy saving, raw materials and environmental protection.

Key words: droplet, condensation process, condensation quantity, area ratio, tetrafluoroethylene, heat transfer

中图分类号:

TK 124

张哲, 赵恩惠, 严雷, 杨文哲, 袁晖, 张秋梅, 田津津. 固体冷表面上液滴凝结过程分析[J]. 化工进展, 2021, 40(10): 5441-5450.

ZHANG Zhe, ZHAO Enhui, YAN Lei, YANG Wenzhe, YUAN Hui, ZHANG Qiumei, TIAN Jinjin. Analysis of droplet condensation process on solid cold surface[J]. Chemical Industry and Engineering Progress, 2021, 40(10): 5441-5450.

图/表 11

参考文献 19

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参数名称	参数大小
图像传感器	1/1.8，211万像素彩色CCD
总像素	1688（H）×1248（V）
电子快门	自动（1/24~1/100000）
液晶显示器	高分辨率TFT液晶显示器，21.5英寸
像素数	1920（H）×1080（V）
光源	LED照明
色温	5700K
输出模式	模拟RGB显示端口（1920×1080像素）

参数名称	参数大小
图像传感器	1/1.8，211万像素彩色CCD
总像素	1688（H）×1248（V）
电子快门	自动（1/24~1/100000）
液晶显示器	高分辨率TFT液晶显示器，21.5英寸
像素数	1920（H）×1080（V）
光源	LED照明
色温	5700K
输出模式	模拟RGB显示端口（1920×1080像素）

参数名称	参数大小
测量项目	温度，湿度（2通道交替测量）
测量量程	温度：-20~70℃（使用内置温度传感器）湿度：0.0%~100%RH（使用9680温湿度传感器）
精度	温度：±0.5℃ 湿度：±5%RH
记录间隔	2~300s，1~60min，14档设置
电源供应	2×1.5V，LR03（AAA）碱性干电池
体积及重量	58mm（宽）×74mm（高）×20mm（厚），70g

参数名称	参数大小
测量项目	温度，湿度（2通道交替测量）
测量量程	温度：-20~70℃（使用内置温度传感器）湿度：0.0%~100%RH（使用9680温湿度传感器）
精度	温度：±0.5℃ 湿度：±5%RH
记录间隔	2~300s，1~60min，14档设置
电源供应	2×1.5V，LR03（AAA）碱性干电池
体积及重量	58mm（宽）×74mm（高）×20mm（厚），70g

参数名称	参数大小
型号	GP10
显示器	5.7英寸TFT彩色LCD
通信通道数	50
额定电源频率	50Hz/60Hz
功耗	最大54V·A