Coupled equivalent circuit models for fluid flow and heat transfer in large connected microchannel networks - The case of oblique fin heat exchangers

This paper presents a simplified equivalent circuit model, which exploits the electric-hydraulic analogy and electric-thermal analogy, to predict the mass flow distribution and temperature distribution in an oblique fin array used in enhanced heat transfer applications. Methods to obtain accurate correlations for calculation of flow-dependent hydraulic 'resistances' are outlined and developed for both primary and secondary channels in the oblique fin array. Appropriate Nusselt number correlations and thermal resistance models are also employed to predict the temperature distribution associated with the mass flow distribution. Detailed full-domain numerical (CFD) simulations are performed to obtain parameters for the hydraulic resistance correlations, and also to serve as benchmarks for the proposed equivalent circuit model. Detailed comparisons between the results of simplified model and numerical simulation showed that the simplified model can accurately predict the mass flow distribution and temperature distribution, within ±5%, for varying fin number, aspect ratio, fin pitch, fin length, oblique angle and inlet velocity. Slightly higher deviations of mass flow prediction are observed for high inlet velocities as a result of the presence of vortices close to the trailing edge of the oblique fin region.