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An Experimental Study of Condensation Heat Transfer of Natural Refrigerants on Aluminum Surface Coated Tubes

天然制冷剂在铝表面涂层管上冷凝传热的实验研究

基本信息

批准号：
15560174
负责人：
INOUE Norihiro
金额：
$ 2.37万
依托单位：
Tokyo University of Marine Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560174/
关键词：
Natural Refrigerants Contact Angle Photocatalyst Repellant Hydrophilic Condensation Heat Transfer Aluminum アンモニア

项目摘要

Trial test tubes and plates, which were coated with repellant and hydrophilic on a surface of aluminum, were produced in this study. The effect that the repellant and hydrophilic was to enhance the condensation heat transfer which was verified experimentally by using pure water, ethanol and HCFC123. The effects of the surface coats were also measured quantitatively by measuring static, dynamic contact angle and downfall angle. The results were obtained as follows.(1)As the value of surface tension of test fluids increases, static contact angle becomes larger independent of surface coats. Static contact angle on the plates that were coated with repellant showed that AL4 βhad the largest value in the case of pure water and ammonia solution and AL4 αhad the largest value in the case of ethanol. Static contact angle on the plates that were coated with hydrophilic confirmed higher wettability independent of the difference of surface tension and coats.(2)Dynamic contact angle whose forward a … More nd backward angle on the plates that were coated with repellant showed a tendency to be the same as the static contact angle, AL4α had the largest value in the case of pure water and AL4 had the largest value in the case of ammonia solution. Also the value of forward angle showed a constant value independent of the difference of surface tension, and the value of backward angle showed lower results with increased surface tension.(3)As the value of surface tension of test fluids increased, a liquid-drop on the plates that were coated with repellant fell down quickly with relatively a small liquid-drop. Also a liquid-drop on the plates of AL4α and AL6 could be seen to fall down quickly with relatively a small liquid-drop, and the effect of the surface coating was verified as superior.(4)Test tubes that were coated with repellant showed the dropwise condensation pattern, high heat flux for surface superheat, and high condensation heat transfer in the case of pure water had the largest surface tension. However, all test tubes that were coated with repellant showed the film condensation pattern, and the condensation heat transfer agreed with the Nusselt Solution for a horizontal tube in the case of ethanol and HCFC123 had a smaller surface tension. The effect of surface coating could not be verified as superior in this case. Less

在本研究中制备了在铝表面上涂覆有排斥剂和亲水性的试验试管和板。通过纯水、乙醇和HCFC-123的实验验证了疏水性和亲水性对冷凝传热的强化作用。通过静态、动态接触角和下落角的测量，定量地测量了表面涂层的效果。结果如下。(1)As测试液的表面张力值增大，静态接触角增大，与表面涂层无关。结果表明，在纯水和氨水溶液中，AL 4 β的静态接触角最大;在乙醇溶液中，AL 4 α的静态接触角最大。静态接触角的板，被亲水涂层证实了较高的润湿性独立的表面张力和涂层的差异。（2）动态接触角，其前向 ...更多信息涂有憎水剂的平板的后向角与静态接触角有相同的趋势，在纯水中AL 4 α最大，在氨水溶液中AL 4 α最大。此外，前向角的值显示出与表面张力的差异无关的恒定值，并且后向角的值显示出随着表面张力的增加而降低的结果。(3)As测试流体的表面张力值增加，涂有排斥剂的板上的液滴以相对小的液滴快速下落。在AL 4 α和AL 6平板上也可以看到液滴快速下降，液滴相对较小，并且表面涂层的效果被验证为上级。（4）在纯水表面张力最大的情况下，涂有憎水剂的试管呈现出滴状凝结形态，表面憎水剂的热流密度高，凝结换热系数高。然而，所有的试管涂有排斥剂显示膜状冷凝模式，和冷凝传热的Nusselt解决方案的情况下，乙醇和HCFC 123具有较小的表面张力的水平管同意。在这种情况下，无法验证表面涂层的效果为上级。少