A method for predicting heat transfer during boiling of mixtures in plain tubes

General heat transfer correlations for flow boiling of zeotropic mixtures in horizontal plain tubes

“…For convective boiling, such mass transfer resistance also appears at the evaporation interface, however, the mixture mass diffusion effect is less pronounced compared with that in nucleate boiling [18,19]. In addition, another two important reasons for the heat transfer degradation in convective boiling are i) the smaller values of the mixture physical properties compared to the ideal values (which are obtained by linear interpolation between the physical properties of the two pure-fluid components) [6,18,20], and ii) the additional sensible heat transfer to the liquid and vapor phases due to the increase of the bubble point temperature along the flow direction caused by the variation of the liquid-phase composition [10], weakening the performance of the boiling process compared to a pure latent heat transfer process in isothermal vaporization of a pure working fluid.…”

“…Such method aims to widen the application range of the correlation, independent of the experimental data. Particularly, two wellknown research efforts were made by Thome [18] and Shah [10], respectively, to propose such modification method. The method proposed by Thome [18] suggests modifying the base pure working fluid correlation by i) using local mixture properties to include the effect of nonlinear variation in mixture physical properties, and ii) employing a mixture correction factor Fc to the nucleate boiling contribution to include the mixture mass diffusion effect.…”

“…It has been demonstrated that this value provides the best predictive performance for mixture flow boiling [74]. Following the same correction approach for the nucleate boiling contribution, Shah [10] modified further the convective boiling contribution of the pure working fluid hcb by using the Bell-Ghaly correction factor [75], and the modified mixture heat transfer coefficient for convective boiling contribution hcb,mix can be calculated by…”

“…Two base pure working fluid correlations developed by Gungor and Winterton [76] in 1986 (GW86) Gungor and Winterton [77] in 1987 (GW87), respectively, were suggested by Thome [18] following the modification method. In addition, three base pure working fluid correlations developed by Shah [78], Gungor and Winterton [77] and Liu and Winterton [73] (LW), respectively, were employed in the modification method by Shah [10], demonstrating good predictive performance with the database collected by Shah [10]. The aforementioned five general correlations were selected in this study; see Table 3.…”

“…Therefore, a general correlation, validated over a wide range of experimental data of zeotropic mixtures, is needed [10].…”