Natural convection heat transfer of water in a horizontal circular gap
Tóm tắt
An experimental study on the natural convection heat transfer on a horizontal downward facing heated surface in a water gap was carried out under atmospheric pressure conditions. A total of 700 experimental data points were correlated using Rayleigh versus Nusselt number in various forms, based on different independent variables. The effects of different characteristic lengths and film temperatures were discussed. The results show that the buoyancy force acts as a resistance force for natural convection heat transfer on a downward facing horizontal heated surface in a confined space. For the estimation of the natural convection heat transfer under the present conditions, empirical correlations in which Nusselt number is expressed as a function of the Rayleigh number, or both Rayleigh and Prandtl numbers, may be used. When it is accurately predicted, the Nusselt number is expressed as a function of the Rayleigh and Prandtl numbers, as well as the gap width-to-heated surface diameter ratio; and uses the temperature difference between the heated surface and the ambient fluid in the definition of Rayleigh number. The characteristic length is the gap size and the film temperature is the average fluid temperature.
Tài liệu tham khảo
Faw R E, Dullforce T A. Holographic interferometry measurement of convective heat transport beneath a heated horizontal plate in air. Int J Heat Mass Transfer, 1981, 24(5): 859–869
Goldstein R J, Sparrow E M, Jones D C. Natural convection mass transfer adjacent to horizontal plates. Int J Heat Mass Transfer, 1973, 16: 1025–1035
Gryzagoridis J. Natural convection from an isothermal downward facing horizontal plate. Int Comm Heat Mass Transfer, 1984, 11:183–190
Schulenberg T. Natural convection heat transfer to liquid metals below downward facing horizontal surfaces. Int J Heat Mass Transfer, 1984, 27(3): 433–441
Schulenberg T. Natural convection heat transfer below downward facing horizontal surfaces. Int J Heat Mass Transfer, 1985, 28(2):467–477
The Japan Society of Mechanical Engineers (JSME). JSME Data Book: Heat Transfer. 4th ed. Tokyo, 1986, 68 (in Japanese)
Theofanous T G, Maguire M, Angelini S, et al. The first results from the ACOPO experiment. Nucl Eng Des, 1997, 169: 49–57
Kwak C E, Song T H. Natural convection around horizontal downward facing plate with rectangular grooves: experiments and numerical simulations. Int J Heat Mass Transfer, 2000, 43:825–838
Radziemska E, Lewandowski W M. Heat transfer by natural convection from an isothermal downward facing round plate in unlimited space. Appl Energy, 2001, 68: 347–366
Friedrich M K, Angirasa D. The interaction between stable thermal stratification and convection under a heated horizontal surface facing downward. Int J Non-linear Mech, 2001, 36:719–729
Incropera F P, David P D. Fundamentals of Heat and Mass Transfer. 5th ed. New York: Wiley, 2002, 543
Wei J J, Yu B, Kawaguchi Y. Simultaneous natural convection heat transfer above and below an isothermal horizontal thin plate. Numer Heat Transfer, Part A, 2003, 44: 39–58
Lloyd J, Moran W R. Natural convection adjacent to horizontal surfaces of various platforms. Trans ASME C: J Heat Transfer, 1974, 96: 443–447