Effect of asymmetrical wall heat flux and wall temperature ratio on mixed convection in a vertical micro-porous-channel with internal heat generation

V. Leela ^a,*, K.N. Seetharamu ^a, Nagabhushanam Kotloni ^b, R. Gangadhara Reddy ^c

a. PES University, Bengaluru, Karnataka, 560085, India    
         b. RV Institute of Technology and Management, Bengaluru, Karnataka, 560076, India    
         c. AMC Engineering College, Bengaluru, Karnataka, 560083, India

Abstract: Mixed convective heat transfer in a vertical parallel plate micro-porous channel with internal heat generation and viscous dissipation, varying wall heat flux ratio and wall temperature ratio at the boundaries is investigated using the Darcy-Brinkman model under local thermal non-equilibrium assumption. Numerical solution for both fluid and solid temperature distributions are obtained by applying the finite element method. The effect of pertinent parameters such as Brinkman number, Rayleigh number, Darcy number, inter-phase heat transfer coefficient, porosity scaled thermal conductivity ratio and solid internal heat generation are discussed. The results indicate that the Nusselt number increases with the increase in the solid internal heat generation as well as Rayleigh number in both wall heat flux ratio and wall temperature ratio boundary conditions. It is observed that with the quantitative increase in viscous dissipation parameter Br, Nusselt number Nu increases in the presence of internal heat generation and it decreases in the absence of internal heat generation, for a specific range of values of wall heat flux ratio and wall temperature ratio. Beyond this range Nu increases with the increase in Br regardless of internal heat generation. For the cases, constant wall temperature and wall heat flux ratios, good correlation is observed in the results obtained with that of available in the literature.

Keywords: Wall heat flux ratio; Wall temperature ratio; Internal heat generation; Mixed convection; Viscous dissipation; Local thermal non-equilibrium