固液表面自由能差强化蒸汽冷凝传热的研究
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摘要
为了考察固液表面自由能差对膜状冷凝传热系数的影响，本文从液膜流动的角度出发，推导出了接触角与冷凝传热系数的关联式。计算结果表明，接触角在一定范围内，膜状冷凝传热系数随着接触角的增大而增大；而当接触角较小(接近0°)时，本文关联式的计算结果与经典的Nusselt理论相符。
本文实验研究了相同冷凝实验条件下的水蒸汽在紫铜基离子注氮表面、紫铜基机械抛光表面、黄铜基DLC表面、黄铜基机械抛光表面上的滴状冷凝传热特性，考察了固液表面自由能差的变化(通过压力来调节)对冷凝传热的影响。实验结果表明，在相同的操作条件下，冷凝传热系数随着固液表面自由能差的增大而增大。紫铜基机械抛光表面的冷凝传热系数和热通量在实验压力为常压、70kPa、46kPa时分别比紫铜基离子注氮表面提高10％、16％、15％。黄铜基DLC表面上冷凝传热系数和热通量在实验压力为常压、70kPa、46kPa、31kPa时比相同条件下黄铜基机械抛光表面分别提高8％、13％、34％、34％。
以乙二醇蒸汽为冷凝工质，实验研究了固液表面自由能差的变化对膜状冷凝传热的影响。实验结果表明，乙二醇在紫铜基离子注氮表面、紫铜基机械抛光表面、黄铜基DLC表面上的膜状冷凝传热系数实验值分别比相同条件下的Nusselt计算值提高40％、28％～42％、25％～43％。实验数据与本文建立的数学模型的计算结果的变化趋势相一致。
In order to study the influence of surface-free-energy difference of solid surface and condensate on the filmwise condensation heat transfer performance, a correlation of the condensation heat transfer coefficient with contact angle has been derived with respect to liquid film flow and heat transfer at vapor-liquid interface. The calculated results for steam filmwise condensation indicate that the heat transfer coefficient increases with the contact angle increasing when the contact angle ranged within a certain degree. When the contact angle is small or approaching 0? the condensation heat transfer coefficient predicted by the correlation is consistent with result of classic Nusselt theory.
A series of specially designed experiments are conducted to verify the impact of the surface free energies difference on the dropwise and film condensation heat transfer characteristics. The magnitude of the surface free energies difference is regulated by only changing the condensation surfaces under the identical operation condensation, in particular, the vapor pressure, with the exclusion of thermo properties effect.
The steam dropwise condensation heat transfer properties at different condensing pressures are experimentally investigated on a variety of treated surface films, such as ion-implanted Nitrogen surface, mechanically polished surface and diamond-like carbonate (DLCO surface on the substrates of brass and copper plates, respectively. The experimental results indicate that the condensation heat flux and heat transfer coefficient increase with the increasing of the magnitude of the surface free energies difference of the solid surface and the condensate liquid, at the identical operating conditions.
Meanwhile, the dependence of filmwise condensation heat transfer on the surface free energies difference of solid surface and liquid on is experimentally studied with the ethylene glycol vapour condensation on surfaces of ion-implanted Nitrogen surface, mechanical polishing surface and DLC surface on the substrates of copper and brass plates, respectively. The experimental obtained heat transfer performance for the treated surfaces is higher than the calculated results of traditional Nusselt theory, also showing the same tendency with those of the correlation established in the present paper.
本文实验研究了相同冷凝实验条件下的水蒸汽在紫铜基离子注氮表面、紫铜基机械抛光表面、黄铜基DLC表面、黄铜基机械抛光表面上的滴状冷凝传热特性，考察了固液表面自由能差的变化(通过压力来调节)对冷凝传热的影响。实验结果表明，在相同的操作条件下，冷凝传热系数随着固液表面自由能差的增大而增大。紫铜基机械抛光表面的冷凝传热系数和热通量在实验压力为常压、70kPa、46kPa时分别比紫铜基离子注氮表面提高10％、16％、15％。黄铜基DLC表面上冷凝传热系数和热通量在实验压力为常压、70kPa、46kPa、31kPa时比相同条件下黄铜基机械抛光表面分别提高8％、13％、34％、34％。
以乙二醇蒸汽为冷凝工质，实验研究了固液表面自由能差的变化对膜状冷凝传热的影响。实验结果表明，乙二醇在紫铜基离子注氮表面、紫铜基机械抛光表面、黄铜基DLC表面上的膜状冷凝传热系数实验值分别比相同条件下的Nusselt计算值提高40％、28％～42％、25％～43％。实验数据与本文建立的数学模型的计算结果的变化趋势相一致。
In order to study the influence of surface-free-energy difference of solid surface and condensate on the filmwise condensation heat transfer performance, a correlation of the condensation heat transfer coefficient with contact angle has been derived with respect to liquid film flow and heat transfer at vapor-liquid interface. The calculated results for steam filmwise condensation indicate that the heat transfer coefficient increases with the contact angle increasing when the contact angle ranged within a certain degree. When the contact angle is small or approaching 0? the condensation heat transfer coefficient predicted by the correlation is consistent with result of classic Nusselt theory.
A series of specially designed experiments are conducted to verify the impact of the surface free energies difference on the dropwise and film condensation heat transfer characteristics. The magnitude of the surface free energies difference is regulated by only changing the condensation surfaces under the identical operation condensation, in particular, the vapor pressure, with the exclusion of thermo properties effect.
The steam dropwise condensation heat transfer properties at different condensing pressures are experimentally investigated on a variety of treated surface films, such as ion-implanted Nitrogen surface, mechanically polished surface and diamond-like carbonate (DLCO surface on the substrates of brass and copper plates, respectively. The experimental results indicate that the condensation heat flux and heat transfer coefficient increase with the increasing of the magnitude of the surface free energies difference of the solid surface and the condensate liquid, at the identical operating conditions.
Meanwhile, the dependence of filmwise condensation heat transfer on the surface free energies difference of solid surface and liquid on is experimentally studied with the ethylene glycol vapour condensation on surfaces of ion-implanted Nitrogen surface, mechanical polishing surface and DLC surface on the substrates of copper and brass plates, respectively. The experimental obtained heat transfer performance for the treated surfaces is higher than the calculated results of traditional Nusselt theory, also showing the same tendency with those of the correlation established in the present paper.
引文
1. E. Schmidt, W. Schurig, W. Sellschop. Versuche uber die kondensation von wasserdampf in film--und tropemform. Tech. Mech. Thermodyn. 1930, 1: 53--63
2．宋永吉等．状冷凝传热机理的研究(1)(2)(3)．化工学报，1990，41：670--687
3. M.Jakob. Heat transfer in evaporation and condensation. Mech. Engng. 1936, 58: 729
4．宋永吉．蒸汽冷凝过程成滴机理的研究及实现滴状冷凝方法的改进．博士学位论文．大连理工大学，1991．
5. Haraguchi T, Schinada R, Takayama T. Drop formation mechanism in dropwise condensation on the ployvinylidene chloride surface. JSME(B), 1989, 55: 3472--3478
6. Song Y J, Xu D Q, Lin J F. A study on the mechanism of dropwise condensation. Int. J Heat Mass Transfer, 1991, 34: 2827--2832.
7. A. Majumdar, I. Mezic. Instability of ultra-thin water films and the Mechanism of droplet formation on hydrophilic surface. Transaction of the ASME, J Heat Transfer, 1999, 121: 964～971
8. Gose E.E, Mucciardi A.N, Baer E. Model for dropwise condensation on randomly distributed sites. Int. J. Heat Mass Transfer, 1967, 10: 15--22
9. Tanasawa I, Tachibana F, Ochiai J. A study on the process of drop growth by coalescence during Dropwise condensation. Bull of JSME, 1973, 16(99): 1367--1375
10. Fatica N, Katz DL, Dropwise condensation. Chem. Eng Prog, 1949, 45: 661--674
11. B.M. Burnside, H.A. Hadi. Digital computer simulation of dropwise condensation from equilibrium droplet to detectable size. Int. J. Heat Mass Transfer, 1999, 42: 3137-3146
12. Tower R E, Westwater J.W. Effect of plate inclination on heat transfer during dropwise condensation of steam. Chem. Eng. Prog, Symposium Series, 1970, 66: 21--25
13．大连理工大学化工原理教研室编．化工原理(上册)．大连理工大学出版社，1993
14．刘旭．Cu-BTA膜表面强化冷凝传热的研究．硕士学位论文．大连理工大学．1995．
15．施明恒，甘永平，马重芳编，沸腾和凝结，高等教育出版社，1995
16. J.W. Rose,. Interphase matter transfer, the condensation coefficient and dropwise condensation. 11th Int. Heat Transfer Conf. 1998, 1: 89--104
17. Peterson. A.C, Westwater J.W, Dropwise condensation of ethylene glycol. Chem. Eng Prog. Symp. Series, 1966, 62(64): 135--142
18. Wilmshurst. R, Rose J.W. Dropwise and filmwise condensation of aniline, ethanediol and nitrobenzene. Proc 5th Int. Heat Transfer Conf, 1974, 3: 269
19. Stylianou S.A., Rose J.W. Dropwise condensation of ethanediol. PCH Physicochemical Hydrodynamics, 1982, 3(3/4): 199--213
20. Utaka Y, Saito A, Ishikawa H, et al, Study on dropwise condensation curves (Dropwise to filmwise transition of propylene glycol, ethylene glycol and glycerol vapors on a copper surface using a monolayer type promoter—part2). JSME Int. J, Series2, 1988, 31: 73--80
21. Topper L, Baer E. Dropwise condensation of vapors and heat-transfer rates. J. Colloid Sci., 1955, 10: 225--226
22．张东昌，实现滴状冷凝新途径的研究，博士学位论文．大连理工大学，1985
23. Erb R.A. U.S. Department of interior office of saline water. R & D Report, 1966, 184
24. Koutsky J A, Walton A G, Baer E. Heterogeneous nucleation of water vapor on high and low energy surface, center for the study of materials. Case Institute of technology, Tech. 1964,6
25. Erb R A, Thelen E. Promoting permanent dropwise condensation. I & E. C., 1965, 57: 49--59
26. Marto P. J, Looney D. J, Rose J W, et al. Evaluation of organic coatings for the promotion of dropwise condensation of steam. Int. J. Heat Mass Transfer, 1986, 29(8): 1109--1116
27．马学虎．PTFE表面上滴状冷凝及滴膜转换突变机制的研究．博士学位论文，大连理工大学，1994
28. G. Koch, D.C. Zhang, Leipertz. A. Condensation of steam on the surface of hard coated copper Dish. Heat and Mass transfer, 1997, 32: 149-156
29. A Leipertz, G. Koch. Dropwise condensation of steam on hard coated surfaces. Heat Mass Transfer, 1998, 6: 379--384
30．江雷．二元协同纳米界面材料的设计和研制．纳米技术在化工塑料行业应用研讨会资料
31. G. Koch, D.C. Zhang, A. Leipertz. Study on plasma enhanced CVD coated material to promote dropwise condensation of steam. Int. J. Heat Mass Transfer, 1998, 41: 1899--1906
32．赵起．实现水蒸汽和有机蒸汽滴状冷凝新表面材料的研究．博士学位论文，大连理工大学，1991
33. Xuehu Ma, John W. Rose, Dunqi Xun, Jifang Lin, Buxuan Wang. Advances in dropwise condensation heat transfer: Chinese research. Chemical Engineering Journal, 2000, 78: 87-93
34．马学虎．固液界面能效应强化蒸汽冷凝传热的机理分析．中国工程热物理学会第十届年会论文集，2001上册：294--298
35. D.E. Hartley, W. Murgatroyd. Criteria for the break-up of thin liquid layers flowing isothermally over solid surfaces. Int. J. Heat Mass Transfer, 1964, 7: 1003--1015
36. S. George Bankoff. Minimum thickness of a draining liquid film, Int. J. Heat Mass Transfer, 1971, 14: 2143--2146
37. J. Mikielewicz, J.R. Moszynski. Minimum thickness of a liquid film flowing vertically down a solid surface. Int. J. Heat Mass Transfer, 1976, 19: 771--776
38. D.T. Hughes, T.R. Bott. Minimum thickness of a liquid film flowing down a vertical tube. Int. J. Heat Mass Transfer, 1998, 41(2): 253-260
39. Andrzej Doniec. Laminar flow of a liquid down a vertical solid surface. Maximum thickness of liquid rivulet. PCH Physico-Chemical Hydrodynamics. 1984, 5(2): 143--152
40. Mohamed S. El-Genk, Hamed H. Saber. Minimum thickness of a flowing down liquid film on a vertical surface. Int. J. heat mass transfer, 2001, 41: 2809--2825
41. Doniec, Flow of a Laminar Liquid Film Down a Vertical Surface. Chemical Engineering Science, 1986, 43(4): 847--854
42. O'neil G A, Westwater J W. Dropwise condensation of steam in electroplated silver surfaces. Int. J. Heat Mass Transfer, 1984, 27: 1539--1549
43．曲敬信，汪泓宏等编．表面工程手册．1．北京：化学工业出版社，1998
44．亚当森A W，顾惕人．表面物理化学．北京：科学出版社，1984
45．层宗淇，戴闽光．胶体化学．北京：高等教育出版社，1985
46. I. Tanawasa, J. Ochiai, Y. Utaka, S. Enya. Experimental study on dropwise condensation-effect of departing drop size. JSME(B), 1976, 42: 2846--2853
47．张克从，张乐浦．晶体生长．北京：高等教育出版社，1985
48. Ichro Tanasawa. Advances in condensation heat transfer. Advances in heat transfer, 1991, 21: 55--139
49. Owens, D.K., and Wendt, R.C., 1967, Estimation of the Surface Free Energy of Polymers, J. Appl. Polymer Sci., 1967, 13: 1741-1747
50．汪泓宏，田民波．离子束表面强化．北京：机械工业出版社，1992
2．宋永吉等．状冷凝传热机理的研究(1)(2)(3)．化工学报，1990，41：670--687
3. M.Jakob. Heat transfer in evaporation and condensation. Mech. Engng. 1936, 58: 729
4．宋永吉．蒸汽冷凝过程成滴机理的研究及实现滴状冷凝方法的改进．博士学位论文．大连理工大学，1991．
5. Haraguchi T, Schinada R, Takayama T. Drop formation mechanism in dropwise condensation on the ployvinylidene chloride surface. JSME(B), 1989, 55: 3472--3478
6. Song Y J, Xu D Q, Lin J F. A study on the mechanism of dropwise condensation. Int. J Heat Mass Transfer, 1991, 34: 2827--2832.
7. A. Majumdar, I. Mezic. Instability of ultra-thin water films and the Mechanism of droplet formation on hydrophilic surface. Transaction of the ASME, J Heat Transfer, 1999, 121: 964～971
8. Gose E.E, Mucciardi A.N, Baer E. Model for dropwise condensation on randomly distributed sites. Int. J. Heat Mass Transfer, 1967, 10: 15--22
9. Tanasawa I, Tachibana F, Ochiai J. A study on the process of drop growth by coalescence during Dropwise condensation. Bull of JSME, 1973, 16(99): 1367--1375
10. Fatica N, Katz DL, Dropwise condensation. Chem. Eng Prog, 1949, 45: 661--674
11. B.M. Burnside, H.A. Hadi. Digital computer simulation of dropwise condensation from equilibrium droplet to detectable size. Int. J. Heat Mass Transfer, 1999, 42: 3137-3146
12. Tower R E, Westwater J.W. Effect of plate inclination on heat transfer during dropwise condensation of steam. Chem. Eng. Prog, Symposium Series, 1970, 66: 21--25
13．大连理工大学化工原理教研室编．化工原理(上册)．大连理工大学出版社，1993
14．刘旭．Cu-BTA膜表面强化冷凝传热的研究．硕士学位论文．大连理工大学．1995．
15．施明恒，甘永平，马重芳编，沸腾和凝结，高等教育出版社，1995
16. J.W. Rose,. Interphase matter transfer, the condensation coefficient and dropwise condensation. 11th Int. Heat Transfer Conf. 1998, 1: 89--104
17. Peterson. A.C, Westwater J.W, Dropwise condensation of ethylene glycol. Chem. Eng Prog. Symp. Series, 1966, 62(64): 135--142
18. Wilmshurst. R, Rose J.W. Dropwise and filmwise condensation of aniline, ethanediol and nitrobenzene. Proc 5th Int. Heat Transfer Conf, 1974, 3: 269
19. Stylianou S.A., Rose J.W. Dropwise condensation of ethanediol. PCH Physicochemical Hydrodynamics, 1982, 3(3/4): 199--213
20. Utaka Y, Saito A, Ishikawa H, et al, Study on dropwise condensation curves (Dropwise to filmwise transition of propylene glycol, ethylene glycol and glycerol vapors on a copper surface using a monolayer type promoter—part2). JSME Int. J, Series2, 1988, 31: 73--80
21. Topper L, Baer E. Dropwise condensation of vapors and heat-transfer rates. J. Colloid Sci., 1955, 10: 225--226
22．张东昌，实现滴状冷凝新途径的研究，博士学位论文．大连理工大学，1985
23. Erb R.A. U.S. Department of interior office of saline water. R & D Report, 1966, 184
24. Koutsky J A, Walton A G, Baer E. Heterogeneous nucleation of water vapor on high and low energy surface, center for the study of materials. Case Institute of technology, Tech. 1964,6
25. Erb R A, Thelen E. Promoting permanent dropwise condensation. I & E. C., 1965, 57: 49--59
26. Marto P. J, Looney D. J, Rose J W, et al. Evaluation of organic coatings for the promotion of dropwise condensation of steam. Int. J. Heat Mass Transfer, 1986, 29(8): 1109--1116
27．马学虎．PTFE表面上滴状冷凝及滴膜转换突变机制的研究．博士学位论文，大连理工大学，1994
28. G. Koch, D.C. Zhang, Leipertz. A. Condensation of steam on the surface of hard coated copper Dish. Heat and Mass transfer, 1997, 32: 149-156
29. A Leipertz, G. Koch. Dropwise condensation of steam on hard coated surfaces. Heat Mass Transfer, 1998, 6: 379--384
30．江雷．二元协同纳米界面材料的设计和研制．纳米技术在化工塑料行业应用研讨会资料
31. G. Koch, D.C. Zhang, A. Leipertz. Study on plasma enhanced CVD coated material to promote dropwise condensation of steam. Int. J. Heat Mass Transfer, 1998, 41: 1899--1906
32．赵起．实现水蒸汽和有机蒸汽滴状冷凝新表面材料的研究．博士学位论文，大连理工大学，1991
33. Xuehu Ma, John W. Rose, Dunqi Xun, Jifang Lin, Buxuan Wang. Advances in dropwise condensation heat transfer: Chinese research. Chemical Engineering Journal, 2000, 78: 87-93
34．马学虎．固液界面能效应强化蒸汽冷凝传热的机理分析．中国工程热物理学会第十届年会论文集，2001上册：294--298
35. D.E. Hartley, W. Murgatroyd. Criteria for the break-up of thin liquid layers flowing isothermally over solid surfaces. Int. J. Heat Mass Transfer, 1964, 7: 1003--1015
36. S. George Bankoff. Minimum thickness of a draining liquid film, Int. J. Heat Mass Transfer, 1971, 14: 2143--2146
37. J. Mikielewicz, J.R. Moszynski. Minimum thickness of a liquid film flowing vertically down a solid surface. Int. J. Heat Mass Transfer, 1976, 19: 771--776
38. D.T. Hughes, T.R. Bott. Minimum thickness of a liquid film flowing down a vertical tube. Int. J. Heat Mass Transfer, 1998, 41(2): 253-260
39. Andrzej Doniec. Laminar flow of a liquid down a vertical solid surface. Maximum thickness of liquid rivulet. PCH Physico-Chemical Hydrodynamics. 1984, 5(2): 143--152
40. Mohamed S. El-Genk, Hamed H. Saber. Minimum thickness of a flowing down liquid film on a vertical surface. Int. J. heat mass transfer, 2001, 41: 2809--2825
41. Doniec, Flow of a Laminar Liquid Film Down a Vertical Surface. Chemical Engineering Science, 1986, 43(4): 847--854
42. O'neil G A, Westwater J W. Dropwise condensation of steam in electroplated silver surfaces. Int. J. Heat Mass Transfer, 1984, 27: 1539--1549
43．曲敬信，汪泓宏等编．表面工程手册．1．北京：化学工业出版社，1998
44．亚当森A W，顾惕人．表面物理化学．北京：科学出版社，1984
45．层宗淇，戴闽光．胶体化学．北京：高等教育出版社，1985
46. I. Tanawasa, J. Ochiai, Y. Utaka, S. Enya. Experimental study on dropwise condensation-effect of departing drop size. JSME(B), 1976, 42: 2846--2853
47．张克从，张乐浦．晶体生长．北京：高等教育出版社，1985
48. Ichro Tanasawa. Advances in condensation heat transfer. Advances in heat transfer, 1991, 21: 55--139
49. Owens, D.K., and Wendt, R.C., 1967, Estimation of the Surface Free Energy of Polymers, J. Appl. Polymer Sci., 1967, 13: 1741-1747
50．汪泓宏，田民波．离子束表面强化．北京：机械工业出版社，1992