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Convective Vaporization of Pure Refrigerants in Enhanced and Integral-Fin Tube Banks

1994; Begell House; Volume: 1; Issue: 4 Linguagem: Inglês

10.1615/jenhheattransf.v1.i4.60

1563-5074

Neelkanth S. Gupte, Ralph L. Webb,

Refrigeration and Air Conditioning Technologies

Convective vaporization data were obtained on staggered tube banks of enhanced nucleate boiling tubes and integral-fin tubes (IFT) with an equilateral pitch-to-diameter ratio of 1.25. Pure refrigerants R-11, R-123, and R-134a were used as working fluids. The data were taken at 4 and 27 C in an apparatus that allows an independent control of vapor quality, mass velocity, and heat flux. The data span vapor qualities of 0 to 0.9, mass velocities of 10 to 28 kg/m2·s, and heat flux of 15 to 48 kW/m2. The data were predicted using a modified superposition model (using 5=1) and also correlated by an asymptotic model. The nucleate boiling components were obtained from pool boiling data, and single-phase heat transfer coefficients were calculated using appropriate correlations for tube banks. The modified superposition model predicted approximately 80% of the GEWA-SE and Turbo-B data within + 20% but did a poor job predicting the integral-fin tube bank data with R-11 at 4 C. Tube banks made of enhanced nucleate boiling tubes, where boiling performance is governed mainly by subsurface cavities, show insignificant effect of forced convection when compared to plain or integral-fin tube banks.