Slug flow heat transfer rate in wavy walls microtubes by ‎applying the modified volume of fluid method

This study explores the enhancement of heat transfer in heated wavy wall microtubes under slug ‎two-phase flow, utilizing a dual-stage Lafaurie-filtered Volume of Fluid (VOF) method‏ ‏in ‎OpenFOAM to effectively capture the liquid-gas interface. The research involves a ‎comprehensive analysis of eight different wall profiles, including triangular, trapezoidal, ‎sinusoidal, and half-sine profiles, to identify the configuration that optimizes the average Nusselt ‎number. Notably, the half-sine configuration proved to be the most effective, yielding ‎approximately a 50% increase in heat transfer rate compared to slug flow in a smooth tube. ‎Parametric investigations into wall amplitude and wavelength suggested that an amplitude of 20 ‎‎µm and a wavelength of 100 µm can significantly enhance heat transfer, resulting in increases by ‎factors of 2.5 and 11, respectively, compared to smooth-wall slug and single-phase flows. ‎Additionally, the study examined the slug flow of the modified geometry to assess the interplay ‎between heat transfer and pressure drop. Although a decrease in wavelength led to an increase in ‎pressure drop, the associated negative impact on heat transfer rate was found to be limited. ‎Ultimately, the research establishes empirical correlations for the average Nusselt number and the ‎Thermal Performance Factor (TPF), achieving prediction accuracies greater than 84%. These ‎insights not only provide practical design principles for microchannel heat exchangers in ‎electronics cooling applications but also pave the way for potential advancements in process ‎intensification, thereby broadening the implications of this research in the field.‎