This experimental study on rhombic shaped microchannels was conducted to understand the effect of a low acute side angle on the Nusselt number and compare the results with the published numerical results for H1 (axially constant heat flux and circumferentially constant temperature) and H2 (constant axial and circumferential wall heat flux) boundary conditions. The hydraulic and heat transfer characteristics of the rhombic geometry with a side angle of 30 deg for different mass flow rates and heat flux inputs are obtained using a three-dimensional (3D) conjugate heat transfer model, which is validated with the experimental results. It is found that the average Nusselt number obtained from the experimental and numerical results can be approximated closely with that computed using the H1 boundary condition. The local Nusselt number of hydrodynamically and thermally developed regions obtained from the numerical analysis is compared with a correlation for the H1 boundary condition. These results will be useful in design and optimization of a rhombic shaped microchannel for electronic cooling applications.

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