喷雾冷却液膜流动特性测试方案优化及传热规律分析

doi:10.11949/0438-1157.20240261

摘要/Abstract

摘要：

喷雾冷却过程中，液滴-液膜-热壁面多子过程交互的强干扰体系造成液膜流动特征的捕捉非常困难，致使喷雾冷却高效换热机理还未得到本质澄清。开展HFE-7000和HFE-7100喷雾液膜流动与传热研究，明确了相机内置感光参数、快门和光圈组合、取样策略等耦合影响下的液膜流动特性测试与诊断方案，针对不同表面均取得了良好的测试效果。提出了基于标准液膜的ADD型误差分析方法，给出了相关参数的偏差和随机误差，获得了不同热流、压力和喷嘴高度下HFE-7100液膜分布和流动过程润湿面积、接触线长度等特征及规律，发现孤立液膜润湿面积随表面温度升高而降低，接触线则随温度而呈现出降低或少数工况降低-升高的趋势，并探讨了液膜流动特征与传热规律的有机联系。

关键词: 喷雾冷却, 液膜流动, 孤立液膜, 误差分析

Abstract:

The liquid film serves as the primary medium directly involved in the spray cooling process and capturing its flow characteristics are crucial. However, accurately capturing these characteristics is extremely challenging due to strong interference from the interaction between droplets, liquid film, and heated wall. Consequently, achieving a comprehensive understanding of efficient heat transfer mechanisms in spray cooling remains elusive. In this study, we investigated the imaging quality of HFE-7000 and HFE-7100 liquid films to establish an appropriate testing and diagnostic approach for the liquid film dynamics, including the coupled factors such as built-in sensitivity parameters of cameras, shutter speed and aperture combinations, and sampling strategies. The method yielded favorable results for various surfaces. The ADD-type error analyses based on standard liquid films was proposed to determine the bias and random errors associated with relevant parameters. The morphologies, wetted area, and contact line length of HFE-7100 spray under different heat fluxes, pressures, and nozzle heights were obtained to explore the mechanisms governing spray cooling. It was observed that the isolated wetted areas decreased with the increasing surface temperature while the contact lines exhibited either a decreasing or occasionally an increasing trend under certain operating conditions. Furthermore, the connection between liquid film dynamics and heat transfer characteristics was discussed and verified.

Key words: spray cooling, liquid film flow, error analyses, HFE-7100

中图分类号:

TK 124

陈引, 赵霄, 杜王芳, 杨竹强, 李凯, 赵建福. 喷雾冷却液膜流动特性测试方案优化及传热规律分析[J]. 化工学报, DOI: 10.11949/0438-1157.20240261.

Yin CHEN, Xiao ZHAO, Wangfang DU, Zhuqiang YANG, Kai LI, Jianfu ZHAO. Optimization of diagnostic method for liquid film dynamics in spray cooling and heat transfer characteristics analysis[J]. CIESC Journal, DOI: 10.11949/0438-1157.20240261.

图/表 12

图1 实验系统及部分实验装置示意图（单位mm）

Fig.1 Schematic of the experimental system and apparatus (unit: mm)

图2 图像处理

Fig.2 Schematic of image processing

图3 ADD型误差分析：偏差和随机误差

Fig.3 ADD type of error analyses: the bias and random errors

图4 标准孤立液膜图像处理过程的偏差标定

Fig.4 Calibration for the bias generated from image processing by the standard isolated films

图5 不同采样策略的处理结果注:(c) 1.4 s拍摄时长

Fig.5 Results of the Aiso-wet¯ with different sampling strategies

图6 不同内部参数（γ、K）的处理结果

Fig.6 Results of the Aiso-wet¯ under different internal parameters （γ、K）

图7 不同γ和K的成像质量对比（P = 0.2 MPa）

Fig.7 Comparison of imaging quality under different γ and K (P = 0.2 MPa)

图8 不同快门大小的处理结果

Fig.8 Results of the Aiso-wet¯ under different shutter speed

图9 不同快门大小的成像质量对比（P = 0.2 MPa, H = 110 mm, Tw = 60.48 °C）

Fig.9 Comparison of imaging quality under different shutter speed (P = 0.2 MPa, H = 110 mm, Tw = 60.48 °C)

图10 不同P和H下的换热特性曲线

Fig.10 Heat transfer curves under different H and P

图11 传热特性与液膜动力学特性间的联系

Fig.11 The relationship between the liquid film dynamics and heat transfer characteristics

图12 热流不断升高时的热表面液膜形貌（P = 0.2 MPa, H = 40.5 mm）

Fig.12 Phenomena occurring on the surface with increasing heat flux (P = 0.2 MPa, H = 40.5 mm)

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