Numerical analysis of microencapsulated phase change suspension flow in wavy porous microchannels with different phase differences

Abstract

The wavy microchannel heat sink (MCHS) with porous fins exhibits tremendous potential for cooling high-power electronic devices. However, due to limitations in existing laboratory equipment capabilities, the underlying mechanisms of complex flow and heat transfer in wavy porous microchannels with varying phase differences could not be revealed, which hindered the further control and optimization of convective heat transfer process. In this study, the convection and performance characteristics of microencapsulated phase change material slurry (MPCMS) flowing through wavy porous microchannels with various phase differences under incompressible, steady and laminar flow conditions are analyzed based on a three-dimensional fluid-solid conjugate model. By utilizing velocity and temperature profiles as well as defining dimensionless parameters such as τ, θ, Nu, Po, R_Nu, R_f, and PEF, the hydrothermal properties of wavy MCHS with MPCMS as coolant are analyzed in depth with respect to the intrinsic connection with phase difference, porous and solid materials, wavy amplitude, wavelength, and Reynolds number, and the performance is compared with that of the pristine straight configuration. The study reveals that fluid flow within the channels is deflected due to phase differences, resulting in a velocity profile resembling a skewed distribution in wavy channel configurations other than φ = 180°. Compared to the wavy porous configurations with phase differences of φ = 0° and 180°, the modes of φ = 30° and 90° as well as φ = 270° exhibit lower and higher pressure drops owing to larger and smaller flow cross-sectional areas, respectively. Aluminum and copper MCHS demonstrate superior overall performance compared to steel, nickel, and silicon in terms of porous/solid materials. However, aluminum is preferred as a raw material when considering manufacturing costs. Within the tested ranges of A and λ, R_Nu and PEF are greater than 1 for all wavy channel configurations, but the difference in φ results in different growth rates. The mode with φ = 270° offers a significant advantage in heat transfer enhancement when pumping power consumption is not a primary concern, while the mode with φ = 0° exhibits a greater advantage in overall performance improvement. Furthermore, for scenarios with lower Re, smaller A and larger λ, the wavy configuration with φ = 270° simultaneously achieves higher heat transfer and overall performance, and is therefore recommended to be preferred. This research uncovers the underlying mechanisms of flow and heat transfer of MPCMS in wavy porous microchannels with varying phase differences, which fills the gaps arising from experimental limitations and bridges the deficiencies in deep mechanistic analysis, and provides valuable insights for the future design and optimization of wavy channels for various heat transfer applications.