Evaporative Heat Transfer with R134a in a Vertical Minichannel

Zahid Anwar

Abstract


Smart cooling solutions are required for modern electronic devices as heat flux is continuously increasing while component size is shrinking day by day. Two phase heat transfer within compact channels can cope with high heat flux applications. Two phase heat transfer in narrow channels was the subject of many studies from last decade. The mechanisms involved, however, are not fully clear and there is still room for further investigations to come up with a general solution. This article reports experimental finding on flow boiling heat transfer of R134a in a resistively heated, smooth vertical stainless steel minichannel. Experiments were conducted at 27 & 32 oC saturation temperature with 100-500 kg/m2 s mass flux and till completion of dryout. The effect of various parameters like, heat flux, mass flux, vapor quality and system pressure was studied. Results indicated that heat transfer was strongly controlled by applied heat flux while insignificant effect of varying mass flux and vapor quality was observed. Experimental findings were compared with various macro and micro scale correlations from literature, this comparison revealed Gungor and Winterton [10] correlation as the most accurate one for predicting local heat transfer coefficients.

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References


S. Kandlikar, Heat transfer and fluid flow in minichannels and microchannels, Elsevier, 2006.

C. M. Callizo, "Flow boiling heat transfer in single vertical channels of small diameters," KTH, Stockholm, 2010.

W. Owhaib, "Experimental heat transfer, pressure drop and flow visualization of R-134a in vertical mini/micro tubes," Doctoral Theis in Energy Technology KTH, Stockholm, 2007.

C. B. Tibirica and G. Ribatski, "Flow boiling heat transfer of R134a and R245fa in a 2.3 mm tube," International Journal of Heat and Mass transfer, pp. 2459-2468, 2010.

C. L. Ong and J. R. Thome , "Macro-tomicrochannel transition in two-phase flow: Part 2 – Flow boiling heat transfer and critical heat flux," Experimental thermal and fluid science, vol. 35, pp. 873-886, 2011.

T. N. Tran, M. W. Wambsganss and D. M. France, "Small circular and rectangular channel boiling with two refrigerants," International Jouranl of Multiphase flow, pp. 485-498, 1996.

G. Lazarek and S. H. Black, "Evaproative heat transfer, pressure drop and critical heat flux in a small veratical tube with R-113," International Journal of Heat and Mass transfer, pp. 945-960, 1982.

M. H. Maqbool, B. Palm and R. Khodabandeh, "Boiling heat transfer of ammonia in vertical smooth mini channels: Experimental results and predictions," International Journal of thermal sciences, pp. 1-9, 2011.

R. Ali, B. Palm and M. H. Maqbool, "Flow Boiling Heat Transfer Characteristics of a Minichannel Up to Dryout Condition," in ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer, Shanghai, 2009.

K. E. Gungor and R. Winterton, "A general correlation for flow boiling in tubes and annuli," International Journal of Heat and Mass transfer, pp. 351-358, 1986.

P. A. Kew and K. Cornwell, "Correlations for the prediction of boiling heat trnsfer in small diameter channels," Applied Thermal Engineering, pp. 705-715, 1997.

S. S. Bertsch, E. A. Groll and S. V. Garimella, "A composite heat transfer correlation for saturated flow boiling in small channels," International Journal of Heat and Mass transfer , pp. 2110-2118, 2009.

M. Cooper, "Saturated nucleate pool boiling, a simple correlation," in Proceedings of the 1st UK National Heat Transfer conference.

Z. Liu and R. H. S. Winterton, "A general correlation for saturated and subcooled flow boiling in tubes and annuli, based on a nucleate pool boiling equation," International Journal of Heat and Mass transfer, pp. 2759-2766, 1991.

D. Mikielewicz, "A new method for determination of flow boiling heat transfer coefficient in conventional diameter channels and minichannels," Heat Transfer Engineering, pp. 276-287, 2010.






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