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Flow boiling heat transfer of refrigerant R21 in microchannel heat sink


Boiling heat transfer in a refrigerant R 21 flow in a microchannel heat sink is studied. A stainless steel heat sink with a length of 120 mm contains ten microchannels with a size of 640×2050 µm at cross-section with a wall roughness of 10 µm. The local heat-transfer coefficient distribution along the heat sink length is obtained. The ranges of parameters are: mass flow from 68 to 172 kg/m2s, heat fluxes from 16 to 152 kW/m2, and vapor quality from 0 to 1. The maximum values of the heat transfer coefficient are observed at the inlet of microchannels. The heat transfer coefficients decrease substantially along the length of channels under high heat flux conditions and, on the contrary, change insignificantly under low heat flux condition. A comparison with the well-known models of flow boiling heat transfer is performed and the range of applicability is defined.

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  1. 1.

    Bar-Coen, A. and Rahim, E., Modeling and Prediction of Two-Phase Microgap Channel Heat Transfer Characteristics, Heat Transfer Eng., 2009, vol. 30, no. 8, pp. 601–625.

    Article  ADS  Google Scholar 

  2. 2.

    Bertsch, S.S., Groll, E.A., and Garimella, S.V., Review and Comparative Analysis of Saturated Flow Boiling in Small Channels, Nanoscale Microscale Therm. Eng., 2008, vol. 12, no. 3, pp. 187–227.

    Article  Google Scholar 

  3. 3.

    Cheng, L.X., Ribatski, G., and Thome, J.R., Two-Phase Flow Patterns and Flow Pattern Maps: Fundamentals and Applications, Appl. Mech. Rev., 2008, vol. 61, no. 5: Art. no. 050802.

  4. 4.

    Kuznetsov, V.V. and Shamirzaev, A.S., Flow Patterns and Flow Boiling Heat Transfer of Freon R318C in an Annular Minichannel, Therm. Aeromech., 2007, vol. 14, no. 1, pp. 53–61.

    Article  Google Scholar 

  5. 5.

    Kuznetsov, V.V. and Shamirzaev, A.S., Flow Boiling Heat Transfer in Two-Phase Micro Channel Heat Sink at Low Water Mass Flux, Microgravity Sci. Technol., 2009, vol. 21(Suppl. 1), pp. 305–311.

    Article  Google Scholar 

  6. 6.

    Lazarek, G.M. and Blake, S.H., Evaporative Heat Transfer, Pressure Drop and Critical Heat Flux in Small Vertical Tube with R-113, Int. J. Heat Mass Transfer, 1982, vol. 25, no. 7, pp. 945–960.

    Article  Google Scholar 

  7. 7.

    Tran, T.N., Wambsganss, M.W., Chyu, M.C., and France, D.M., A Correlation for Nucleate Flow Boiling in a Small Channel, Proc. Int. Conf. on Compact Heat Exchangers for Process Industries, 1997, pp. 291–304.

  8. 8.

    Kuznetsov, V.V. and Shamirzaev, A.S., Boiling Heat Transfer for Freon R21 in Rectangular Minichannel, Heat Transfer Eng., 2007, vol. 28, pp. 738–745.

    Article  ADS  Google Scholar 

  9. 9.

    Lee, H.J. and Lee, S.Y., Heat Transfer Correlation for Boiling Flows in Small Rectangular Horizontal Channels with Low Aspect Ratios, Int. J. Multiphase Flow, 2001, vol. 27, pp. 2043–2062.

    MATH  Article  Google Scholar 

  10. 10.

    Qu, W. and Mudawar, I., Flow Boiling Heat Transfer in Two-Phase Micro-Channel Heat Sinks-I. Experimental Investigation and Assessment of Correlation Methods, Int. J. Heat Mass Transfer, 2003, vol. 46, pp. 2755–2771.

    Article  Google Scholar 

  11. 11.

    Sumith, B., Kaminaga, F., and Matsumura, K., Saturated Flow Boiling ofWater in a Vertical Small Diameter Tube, Exp. Therm. Fluid Sci., 2003, vol. 27, pp. 789–801.

    Article  Google Scholar 

  12. 12.

    Steinke, M.E. and Kandlikar, S.G., An Experimental Investigation of Flow Boiling Characteristics of Water in Parallel Microchannels, J. Heat Transfer, 2004, vol. 126, pp. 518–526.

    Article  Google Scholar 

  13. 13.

    Kew, P.A. and Cornwell, K., Correlation for the Prediction of Boiling Heat Transfer in Small Diameter Channels, Appl. Thermal Eng., 1997, vol. 17, pp. 705–715.

    Article  Google Scholar 

  14. 14.

    Taitel, Y., Barnea, D., and Dukler, A.E., Modeling Flow Pattern Transition for Steady Upward Gas-Liquid Flow in Vertical Tubes, AIChE J., 1980, vol. 26, pp. 345–354.

    Article  Google Scholar 

  15. 15.

    Liu, Z. and Winterton, R.H., A General Correlation for Saturated and Subcooled Flow Boiling in Tubes and Annuli, Based on a Nucleate Pool Boiling Equation, Int. J. Heat Mass Transfer, 1991, vol. 34, pp. 2759–2766.

    Article  Google Scholar 

  16. 16.

    Cooper, M.G., Saturation Nucleation Pool Boiling—A Simple Correlation, IChemE Symp. Ser., 1984, vol. 84, pp. 785–793.

    Google Scholar 

  17. 17.

    Danilova, G.N., Correlation of Boiling Heat Transfer Data for Freons, Heat Transfer-Soviet Res., 1970, vol. 2, no. 2, pp. 73–78.

    Google Scholar 

  18. 18.

    Balasubramanian, P. and Kandlikar, S.G., An Extension of the Flow Boiling Correlation to Transition, Laminar and Deep Laminar Flows in Minichannels and Microchannels, Heat Transfer Eng., 2004, vol. 25, no. 3, pp. 86–93.

    Article  ADS  Google Scholar 

  19. 19.

    Kandlikar, S.G., Similarities and Differences between Flow Boiling in Microchannels and Pool Boiling, Heat Transfer Eng., 2010, vol. 31, no. 3, pp. 159–167.

    Article  ADS  Google Scholar 

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Correspondence to V. V. Kuznetsov.

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Kuznetsov, V.V., Shamirzaev, A.S. Flow boiling heat transfer of refrigerant R21 in microchannel heat sink. J. Engin. Thermophys. 19, 306–317 (2010).

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  • Heat Transfer
  • Heat Sink
  • Froude Number
  • Steam Generator
  • Local Heat Transfer