Application of thermodynamic models to estimating the convective flow boiling heat transfer coefficient of mixtures

Abstract

A large number of experiments has been performed to measure the forced convective and nucleate flow boiling heat transfer coefficient of three different none-volatile mixtures at different heat fluxes (up to 175kWm−2) and five different volumetric concentrations (10–50% of heavier component). The test mixtures include water/glycerol, water/monoethylene glycol (MEG), and water/diethylene glycol (DEG). The experimental apparatus provides conditions to investigate the influence of the main operating parameters such as: heat flux, concentration, and flow rate of fluid on the forced convective and flow boiling heat transfer coefficient. It is shown that physical properties of the mixtures have a considerable effect on the prediction of flow boiling heat transfer coefficients by the predictive correlations. In almost all of the predictive correlations, physical properties are strongly involved which can be estimated by different thermodynamic models. This work demonstrates that thermodynamic models for the calculation of specific heat, liquid density and heat of vaporization do not obtain identical results and consequently, the heat transfer coefficient obtained from a specified predictive correlation (Chen type model) can be tolerated according to the used thermodynamic model for the calculation of the physical properties. This point has been ignored by the investigators and they compare their experimental data with the correlations without specifying that, which one of the thermodynamic models has to be used for the obtaining of the thermo-physical properties. After reading the present study, a new vision can be opened to the readers interested in prediction of the flow boiling heat transfer coefficient and may help the researchers to reliably predict the thermo-physical properties of fluids particularly for forced convective and boiling phenomena.