ISSN Online: 2377-424X
ISBN Print: 0-85295-345-3
International Heat Transfer Conference 10
A NUMERICAL STUDY OF EVAPORATIVE HEAT TRANSFER OF NONAZEOTROPIC BINARY MIXTURES IN A VERTICAL TUBE (THE EFFECT OF NONIDEALITY OF MIXTURES )
要約
Numerical analysis has been conducted for an evaporative heat transfer of upward annular two-phase flow of nonazeotropic binary mixtures in a vertical tube. Conservation equations of overall mass, momentum, energy and species mass have been solved for each phase numerically with a finite difference method. In the computation, phase equilibrium characteristics of nonideal mixtures were taken into account.
What is the characteristics of evaporative heat transfer of mixtures and how they are affected by nonideality of mixtures were examined. Heat transfer coefficient is found to decrease in some conditions toward the downstream in spite of the increase of quality. This is quite different from the tendency normally expected for single component two-phase flows. The effect of nonideality of mixtures on heat transfer is not negligible and should carefully be taken into consideration in some cases. Especially, it affects the quality and the equilibrium temperature seriously. Effects of nonideality of mixtures are large even for some mixtures for which the difference between the saturation temperatures of two pure components is small. In such a case, the calculation of phase equilibrium chart is of importance.
What is the characteristics of evaporative heat transfer of mixtures and how they are affected by nonideality of mixtures were examined. Heat transfer coefficient is found to decrease in some conditions toward the downstream in spite of the increase of quality. This is quite different from the tendency normally expected for single component two-phase flows. The effect of nonideality of mixtures on heat transfer is not negligible and should carefully be taken into consideration in some cases. Especially, it affects the quality and the equilibrium temperature seriously. Effects of nonideality of mixtures are large even for some mixtures for which the difference between the saturation temperatures of two pure components is small. In such a case, the calculation of phase equilibrium chart is of importance.