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  • 1. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. Boiling heat transfer of R-22, R-134a, and CO2 in horizontal smooth minichannels* Kwang-Il Choia, A.S. Pamitran a, Chun-Young Oh b, Jong-Taek Oh c,* A Graduate School, Chonnam National University, San 96-1, Dunduk-Dong, Yeosu, Chonnam 550-749, Republic of Korea B Refrigeration Research Institute, Chonnam National University, San 96-1, Dunduk-Dong, Yeosu, Chonnam 550-749, Republic of Korea C Department of Refrigeration and Air Conditioning Engineering, Chonnam National University, San 96-1, Dunduk-Dong, Yeosu, Chonnam 550-749, Republic of Korea Sudheer Nandi (Ph.D.),M.Tech,MBA. Sustainable Energy . S.korea

2. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 2 http://www.sciencedirect.com/science/article/pii/S0140700702000403# http://www.youtube.com/watch?v=s-YmfZNKnlU 3. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 3 Qualitative classification flow regimes . MIT Department of Nuclear Science and Engineering 4. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 4 5. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 5 Heat transfer and flow regimes in a vertical heated channel. (Thermal nonequilibrium effec ts have been neglected in sketching the bulk temperature) 6. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. Abstract This study examined convective boiling heat transfer in horizontal minichannels using R-22, R-134a, and CO2. The local heat transfer coefficients were obtained for heat fluxes ranging from 10 to 40 kW 2 , mass fluxes ranging from 200 to 600 kg 2 1 , a saturation temperature of 10 C, and quality up to 1.0. The test section was made of stainless steel tubes with inner diameters of 1.5 mm and 3.0 mm, and a length of 2000 mm. The section was heated uniformly by applying an electric current to the tubes directly. Nucleate boiling heat transfer was the main contribution, particularly at the low quality region. An increasing and decreasing heat transfer coefficient occurred at the lower vapor quality with increasing heat flux and mass flux. The mean heat transfer coefficient ratio of R-22:R-134a:CO2 was approximately 1.0:0.8:2.0. Laminar flow was observed in the minichannels. A new boiling heat transfer coefficient correlation based on the superposition model for refrigerants in minichannels was developed with a mean deviation of 11.21%. Keywords: Refrigerant; R-22; R-134a; R-744; Carbon dioxide; Experiment; Heat transfer; Boiling; Micro channel; smooth tube; Horizontal tube 6 7. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 7 8. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 8 Experimental apparatus The experimental test facility and test section. 9. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. Experimental conditions 9 10. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 10 11. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 11 The effect of mass flux on heat transfer coefficient: (a)R-22, (b) R-134a, and (c) CO2 12. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. The experimental data on Wojtan et al. [20] flow pattern map for R-22. 12 13. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 13 The effect of heat flux on heat transfer coefficient: (a) R-22,(b) R-134a, and (c) CO2. 14. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 14 The comparison of the heat transfer coefficient The effect of inner tube diameter on heat transfer coefficient for R-22. 15. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 15 Development of a new correlation 16. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 16 17. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 17 Two-phase heat transfer multiplier as a function of 2 Diagram of the experimental heat transfer coefficient, hexp., vs prediction heat transfer coefficient, hpred. Heat transfer coefficient comparisonNucleate boiling contribution 18. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 18 19. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. References [1] Z.Y. Bao, D.F. Fletcher, B.S. Haynes, Flow boiling heat transfer of freon R11 and HCFC123 in narrow passages, Int. J.Heat Mass Transfer 43 (2000) 3347e3358. [2] W. Zhang, T. Hibiki, K. Mishima, Correlation for flow boiling heat transfer in mini-channels, Int. J. Heat Mass Transfer 47 (2004) 5749e5763. [3] S.G. Kandlikar, M.E. Steinke, Predicting heat transfer during flow boiling in minichannels and microchannels, ASHRAE Trans. CH-03-13-1 (2003) 667e67 6. [4] T.N. Tran, M.W. Wambsganss, D.M. France, Small circularand rectangular-channel boiling with two refrigerants, Int. J. Multiphase Flow 22 (3) (1996) 48 5e498. [5] J. Pettersen, Flow vaporization of CO2 in microchannels tubes, Exp. Therm. Fluid Sci. 28 (2004) 111e121. [6] C.Y. Park, P.S. Hrnjak, Flow boiling heat transfer of CO2 at low temperatures in a horizontal smooth tube, ASME Trans. 127 (2005) 1305e1312. [7] Y. Zhao, M. Molki, M.M. Ohadi, S.V. Dessiatoun, Flow boiling of CO2 in microchannels (DA-00-2-1), ASHRAE Trans. (2000) 437e445. [8] R. Yun, Y. Kim, M.S. Kim, Convective boiling heat transfer characteristics of CO2 in microchannels, Int. J. Heat. Mass Transfer 48 (2005) 235e242. [9] S.H. Yoon, E.S. Cho, Y.W. Hwang, M.S. Kim, K. Min, Y. Kim, Characteristics of evaporative heat transfer and pressure drop of carbon dioxide and correlation dev elopment, Int. J. Refrigeration 27 (2004) 111e119. [10] A.S. Pamitran, K.I. Choi, J.T. Oh, H.K. Oh, Forced convective boiling heat transfer of R-410A in horizontal minichannels, Int. J. Refrigeration 30 (2007) 155e165. [11] J.P. Wattelet, J.C. Chato, A.L. Souza, B.R. Christoffersen, Evaporative characteristics of R-12, R-134a, and a mixture at low mass fluxes, ASHRAE Trans . 94-2-1 (1994) 603e615. [12] D.S. Jung, M. McLinden, R. Radermacher, D. Didion, A study of flow boiling heat transfer with refrigerant mixtures, Int. J. Heat Mass Transfer 32 (9) (1 989) 1751e1764. [13] M.M. Shah, Chart correlation for saturated boiling heat transfer: equations and further study, ASHRAE Trans. 2673 (1988) 185e196. [14] K.E. Gungor, H.S. Winterton, Simplified general correlation for saturated flow boiling and comparisons of correlations with data, Chem. Eng. Res. 65 (19 87) 148e156. 19 20. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. [15] J.C. Chen, A correlation for boiling heat transfer to saturated fluids in convective flow, Ind. Eng. Chem. Process Des. Dev. 5 (1966) 322e329. [16] C.S. Kuo, C.C. Wang, In-tube evaporation of HCFC-22 in a 9.52 mm micro-fin/smooth tube, Int. J. Heat Mass Transfer 39 (1996) 2559e2569. [17] P.A. Kew, K. Cornwell, Correlations for the prediction of boiling heat transfer in small-diameter channels, Appl. Therm. Eng. 17 (8e10) (1997) 705e715. [18] G.M. Lazarek, S.H. Black, Evaporative heat transfer, pressure drop and critical heat flux in a small diameter vertical tube with R-113, Int. J. Heat Mass Transfe r 25 (1982) 945e960. [19] M.W. Wambsganss, D.M. France, J.A. Jendrzejczyk, T.N. Tran, Boiling heat transfer in a horizontal small-diameter tube, J. Heat Transfer 115 (1993) 963e975 [20] L. Wojtan, T. Ursenbacher, J.R. Thome, Investigation of flow boiling in horizontal tubes: part I e a new diabatic two-phase flow pattern map, Int. J. Heat Mass Transfer 48 (2005)2955e2969. [21] N. Kattan, J.R. Thome, D. Favrat, Flow boiling in horizontal tubes: part 1 e development of a diabatic two-phase flow pattern map, J. Heat Transfer 120 (1998) 140e147. [22] D. Steiner, Heat transfer to boiling saturated liquids, in:Verein Deutcher Ingenieure (Ed.), VDI-Warmeatlas. (VDI Heat Atlas), VDI-Gessellschaft Verfahrenst echnik und Chemieinge nieurwesen (GCV), Dusseldorf, Germany, 1993 (J.W. Fullarton, translator). [23] Y.Y. Yan, T.F. Lin, Evaporation heat transfer and pressure drop of refrigerant R-134a in a small pipe, Int. J. Heat Mass Transfer 41 (1998) 4183e4194. [24] M.G. Cooper, Heat flow rates in saturated nucleate pool boiling e a wide-ranging examination using reduced properties, Advances in Heat Transfer 16 (1984) 1 57e239 (Academic Press). [25] K. Stephan, M. Abdelsalam, Heat-transfer correlations for natural convection boiling, Int. J. Heat Mass Transfer 23 (1980) 73e87. [26] D. Chisholm, A theoretical basis for the LockharteMartinelli correlation for two-phase flow, Int. J. Heat Mass Transfer 10 (1967) 1767e1778. [27] D. Jung, Y. Kim, Y. Ko, K. Song, Nucleate boiling heat transfer coefficients of pure halogenated refrigerants, Int. J. Refrigeration 26 (2003) 240e248. 20 21. Thermal Energy Conversion Control Lab. Chonbuk NatI Univ. 21 Thank you for listening

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