Purpose - To provide modeling approaches of increasing levels of complexity for the analysis of convective heat transfer in microchannels which offer adequate descriptions of the thermal performance, while allowing easier manipulation of microchannel geometries for the purpose of design optimization of microchannel heat sinks. Design/methodology/approach - A detailed computational fluid dynamics model is first used to obtain baseline results against which five approximate analytical approaches are compared. These approaches include a 1D resistance model, a fin approach, two fin-liquid coupled models, and a porous medium approach. A modified thermal boundary condition is proposed to correctly characterize the heat flux distribution. Findings - The results obtained demonstrate that the models developed offer sufficiently accurate predictions for practical designs, while at the same time being quite straightforward to use. Research limitations/implications - The analysis is based on a single microchannel, while in a practical microchannel heat sink, multiple channels are employed in parallel. Therefore, the optimization should take into account the impact of inlet/outlet headers. Also, a prescribed pumping power may be used as the design constraint, instead of pressure head. Practical implications - Very useful design methodologies for practical design of microchannel heat sinks. Originality/value - Closed-form solutions from five analytical models are derived in a format that can be easily implemented in optimization procedures for minimizing the thermal resistance of microchannel heat sinks.
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