每年出版 8 期
ISSN 打印: 1065-5131
ISSN 在线: 1563-5074
Indexed in
HEAT TRANSFER AND PRESSURE DROP DURING EVAPORATION OF R-410A IN ALUMINUM EXTRUDED ENHANCED TUBES
摘要
The literature shows that axial microfins and spokes are promising means for enhancing evaporation of refrigerants in tubes. However, studies are lacking and available ones are generally limited to large diameter tubes. In this study, evaporation heat transfer and pressure drop tests were performed on four tubes−smooth, helical microfin, axial microfin, and spoke−having 7.0 mm outer diameter for the mass flux from 50 to 250 kg/m2s using R-410A. During the test, the heat flux and the saturation temperature were maintained at 3.0 kW/m2 and 8°C. Above 150 kg/m2s, the best heat conductance (hiAi) enhancement was obtained from the axial microfin tube. At lower mass fluxes, the spoke tube yielded the best enhancement. Possible reasoning is provided based on the flow pattern in each tube. As for the pressure drop, the spoke tube yielded significantly higher pressure drop than other tubes. In addition, the pressure drops of the axial microfin tube were higher than those of the helical microfin tube. With proper selection of the fin height, the axial microfin tube may perfrom better than the helical microfin tube except at a low mass flux. At a low mass flux, where stratified flow prevails, the axial microfin is likely to interrupt peripheral propagation of liquid film and deteriorate the heat transfer.
-
Collier, J.G. and Thome, J.R., Convective Boiling and Condensation, 3rd ed., Oxford, UK: Oxford University Press, 1994.
-
Doretti, L., Zilio, C., Mancin, S., and Cavallini, A., Condensation Flow Patterns inside Plain and Microfin Tubes: A Review, Int. J. Refrig., vol. 36, pp. 567-587, 2013.
-
Eckels, S.J. and Pate, M.B., In-Tube Evaporation and Condensation of Refrigerant-Lubricant Mixtures of HFC-134a and CFC-12, ASHRAE Transact., vol. 97, no. 2, pp. 62-70, 1991.
-
Friedel, L., Improved Pressure Drop Correlations for Horizontal and Vertical Two-Phase Pipe Flow, 3R Int., vol. 18, pp. 485-492, 1979.
-
Graham, D., Chato, J.C., and Newell, T.A., Heat Transfer and Pressure Drop during Condensation of Refrigerant 134a in an Axially Grooved Tube, Int. J. Heat Mass Transf., vol. 42, pp. 1935-1944, 1999.
-
Gungor, K.E. andWinterton, R.H.S., Simplified General Correlations for Saturated Flow Boiling and Comparisons of Correlations with Data, Can. J. Chem. Eng., vol. 65, no. 1, pp. 148-156, 1987.
-
Ito, M. and Kimura, H., Boiling Heat Transfer and Pressure Drop in Internal Spiral Grooved Tubes, Bull. JSME, vol. 22, no. 17, pp. 1251-1257, 1979.
-
Kandlikar, S.G., A General Correlation for Two-Phase Boiling Heat Transfer Coefficient inside Horizontal and Vertical Tubes, J. Heat Transf., vol. 112, pp. 219-228, 1990.
-
Kandlikar, S.G. and Raykoff, T., Flow Boiling of Refrigerants in Microfin Tubes, J. Enhanced Heat Transf., vol. 24, pp. 231-242, 2017.
-
Kim, N.-H., Condensation Heat Transfer and Pressure Drop of R-410A in Flat AluminumMultiport Tubes, Heat Mass Transf., vol. 54, pp. 523-535, 2018.
-
Kim, N.-H., Personal Communication with LG Electronics, 2019.
-
Kim, N.-H., Kim, C.-H., and Han, H.-S., Heat Transfer and Pressure Drop during Condensation of R-410A in Aluminum Extruded Enhanced Tubes, Submitted to Int. J. Air-Cond. Refrig., 2020.
-
Kline, S.J. and McClintock, F.A., The Description of Uncertainties in Single Sample Experiments, Mech. Eng., vol. 75, pp. 3-9, 1953.
-
Moreno-Quiben, J. and Thome, J.R., Flow Pattern Based Two-Phase Frictional Pressure Drop Model for Horizontal Tubes, Part II: New Phenomenological Model, Int. J. Heat Fluid Flow, vol. 28, pp. 1060-1072, 2007.
-
Muzzio, A., Niro, A., and Arosio, S., A Review on Heat Transfer and Pressure Drop during Evaporation and Condensation of R-22 inside 9.52 mm O.D. Microfin Tubes of Different Geometries, J. Enhanced Heat Transf., vol. 24, pp. 459-472, 2017.
-
Newell, T.A. and Shah, R.K., An Assessment of Refrigerant Heat Transfer, Pressure Drop and Void Fraction Effects in Microfin Tubes, Int. J. HVAC&R, vol. 7, no. 2, pp. 125-153, 2001.
-
Pearson, J.F. and Young, E.H., Simulated Performance of Refrigerant-22 Boiling inside of Tubes in a Four Pass Shell and Tube Heat Exchanger, AIChE Symp. Ser., vol. 66, no. 102, pp. 164-173, 1970.
-
Reid, R.S., Pate, M.B., and Bergles, A.E., A Comparison of Augmentation Techniques during In-Tube Evaporation of R-113, J. Heat Transf., vol. 113, pp. 451-458, 1991.
-
Schlunder, E.U. and Chawla, J., Local Heat Transfer and Pressure Drop for Refrigerants Evaporating in Horizontal Internally Finned Tubes, Proc. Int. Cong. Refrig., paper no. 2.47, 1967.
-
Wen, M.-Y. and Shieh, S.-S., Saturated Flow Boiling Heat Transfer in Internally Spirally Knurled/Integral-Finned Tubes, J. Heat Transf., vol. 117, pp. 245-248, 1995.
-
Wilson, E.E., A Basis for Rational Design of Heat Transfer Apparatus, Transact. ASME, vol. 37, pp. 47-70, 1915.
-
Yang, C.-M. and Hrnjak, P., Effect of Straight Microfins on Heat Transfer and Pressure Drop of R-410A during Evaporation in Round Tubes, Int. J. Heat Mass Transf., vol. 117, pp. 924-939, 2018.
-
Yang, C.-M. and Hrnjak, P., Visualization of Two-Phase Flow of R-410A in Horizontal Smooth and Axial Micro-Finned Tubes, Int. J. Heat Mass Transf., vol. 138, pp. 49-58, 2019.