Effect of Surface Roughness in Parallel-Plate Microchannels on Heat Transfer

Abstract

In this study, the effect of surface roughness on convective heat transfer in two-dimensional parallel plate microchannels is analyzed numerically for steady-state, single-phase, developing, and laminar air flow in the slip flow regime. Slip velocity and temperature jump at wall boundaries are imposed to observe the rarefaction effect. The effect of triangular roughness elements on Nusselt number are compared to cases with smooth surfaces. The results indicate that increasing surface roughness reduces heat transfer in continuum. However, in slip flow regime, an increase in the Nusselt number with increasing roughness height is observed; this increase being more pronounced at low rarefied flows. It is also found that the presence of axial conduction and viscous dissipation have increasing effects on heat transfer in smooth and rough channels, compared to cases where they are neglected.

A review of heat and fluid flow characteristics in microchannel heat sinks

“…36,39 However, it is essential for microchannels even in laminar region 37 ; although it is a debated topic in the literature. 2,30,31,33,39,40,[74][75][76][77][78][79][80][81][82][83] Surface roughness along the microchannel 80 is schematically shown in Figure 4. ε is the roughness height, and the effect of surface roughness increases as the height increases.…”

“…In macroscale (conventional) channels, the importance of surface roughness pronounced only in turbulent regime 36,39 . However, it is essential for microchannels even in laminar region 37 ; although it is a debated topic in the literature 2,30,31,33,39,40,74‐83 . Surface roughness along the microchannel 80 is schematically shown in Figure 4.…”

A Numerical Investigation of Turbulent Flows through an Artificially Roughened Solar Air Heater

“…The duct formed by the absorber and the bottom plate is the air flow duct, where the air is heated by the absorbed solar radiation on the absorber [1,2]. Among the many effective ways to augment the convective heat transfer rate in channel flows, those that increase the heat transfer surface area and those that increase turbulence inside the channel with fins or corrugated surfaces [3][4][5] and surface roughness [6][7][8] have been the most popular. Indeed, the use of artificial roughness in different forms and shapes is known to be the most effective and economic way of improving the performance of a solar air heater.…”