Study of pressure drop and heat transfer in micro channel branch with varying bifurcation angle, aspect ratio, and temperature

Abstract

The current study is focused on studying the effects of temperature and bifurcation angle on pressure drop as well as heat transfer in micro-channels for two Newtonian fluids - water and air. The microchannel of aspect ratio 1 and 1.5 with hydraulic diameters 500 microns and 600 microns were investigated for a fully developed laminar flow bifurcated after the flow reached its hydrodynamic developed length with bifurcation angles of 30?,60?,90?,120? and 150?. Temperatures of 318.15K, 333.15K, and 345.15K are induced on top surface of the microchannel for mentioned bifurcated angles to analyze the effective angle at which the heat transfer was highest with minimal pressure drop. The branching of the microchannel was done after the flow has reached its hydrodynamically developed length, which is calculated based on the hydraulic diameter [11] and flow is thermally developing due to the wake effects at entrance region [29]. Accordingly, the test section was modeled in Ansys, imposing constant temperature boundary condition on one face of the ducts of varied aspect ratios. The 3-D simulations are performed in Ansys - Fluent software with the laminar model and conditions of the steady state, considering fluids as incompressible and irrotational. The pressure drop and heat transfer characteristics of the various configurations are tabulated for examining and to draw comparisons. It is observed that both the heat transfer and pressure drop increases with bifurcation angle. The relative bifurcation angle between two symmetrically branched microchannels at which the pressure drop and heat transfer are optimum is concluded.