Variable-property effect on liquid flow and heat transfer in microchannels

Numerical investigation was conducted in an effort to verify the variable-property effect of thermally developing flow in microchannel cooling passages. Temperature-dependent viscosity and thermal conductivity of liquid water were taken into account in theoretical modeling. Two-dimensional simulation was performed for low Reynolds number flow in a 100 μm single channel subjected to localized heat flux and different inlet temperatures. The fundamental characteristics of flow and thermal re-development were carefully analyzed. The heat transfer enhancement was described by defining the peak value and location of relative Nusselt number distribution as ΔNu%max and Xmax. Strong non-linear interaction mechanism prevailed in the correlation of ΔNu%max and Xmax due to high heat flux condition and dramatic rise of liquid temperature.