Heat transfer in nucleate pool boiling of multicomponent mixtures

Steady state pool boiling heat transfer coefficients have been obtained experimentally for acetone–isopropanol–water and acetone–MEK (methyl ethyl ketone)–water ternary systems. The data show that, for a given heat flux, the heat transfer coefficients of mixtures are lower than those obtained for pure components constituting the mixture. The measured heat transfer coefficients were compared with predictions from literature correlations for pool boiling of multicomponent mixtures. In all the cases, overestimation or underestimation of the data was observed. The literature correlations incorporate an ‘ideal’ heat transfer coefficient and a correction term for the presence of other liquids. Part of the uncertainty associated with the literature correlations on comparison with the present data appears to be due to the uncertainty in estimating the ideal heat transfer coefficient. The methods suggested by the earlier authors found to be not applicable for the present heating surface–liquid combinations. Therefore, in the present study, two different correlations were tried for the ideal heat transfer coefficient and it was found that the performance of the literature correlations improved considerably. However, the methods reported in the literature and the correlations tried in the present study to estimate ideal heat transfer coefficient did not consider heating surface–liquid interaction and the effect of heating surface microroughness in boiling. Therefore, a correlation to estimate the ideal heat transfer coefficient has been proposed taking into account surface–liquid interaction parameter and surface roughness group. A new correlation to estimate mixture heat transfer coefficients has been proposed in the present study in terms of an ideal heat transfer coefficient and a correction term. In general, the correction term in binary mixtures is obtained by incorporating the binary diffusivity of the mixture. In multicomponent systems, the multicomponent diffusion coefficients have to be incorporated in the expression for the correction term. The mixture heat transfer coefficient correlation along with the correlation for ideal heat transfer coefficient proposed in the present study predicts the present experimental data as well as literature data satisfactorily. The heat transfer coefficient was found to be a function of the difference between the equilibrium vapor and liquid concentration of the light component(s) and the minimum heat transfer coefficient occurs at the maximum of this value. 2004 Elsevier Inc. All rights reserved.