Theoretical and Analytical Methods for Determining Heat Transfer Coefficients in Evaporation Processes

Abstract

In open-surface evaporation systems, the simultaneous transfer of heat and mass is vital for establishing the interrelated exchange of energy and mass between liquid and gas phases. This research offers a comprehensive examination of the physical mechanisms that control evaporation in both natural and forced convection scenarios. It also assesses different theoretical and empirical approaches for calculating the heat transfer coefficient. It has been shown through experiments and numerical analyses conducted in the past that the precision of predictions regarding heat and mass transfer is greatly influenced by factors such as geometrical configurations, convection regimes, and measurement accuracy. Various analytical methods are examined, such as the heat balance equation method that connects heat flux to temperature difference and evaporation rate through interfacial energy balance, and the dimensional analysis method that formulates general correlations based on important dimensionless numbers like Nusselt, Prandtl, Reynolds, and Rayleigh. Moreover, the heat–mass transfer analogy offers a practical framework for estimating one coefficient based on the other by taking advantage of the similarity between temperature and concentration fields. Furthermore, the Ackermann correction factor is implemented to consider the effect of vapor flow on the heat transfer, thereby improving estimations of the heat transfer coefficient during evaporation and diffusion. This research creates an extensive framework for the analysis of open-surface evaporation and the enhancement of heat and mass transfer coefficient predictions. This is achieved through a combination of theoretical, experimental, and analogy-based methods, leading to improvements in the design and functioning of thermal and evaporative systems.