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Open AccessArticle

Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution

1
MITIS SA, Rue del Rodje Cinse 98, 4102 Seraing, Belgium
2
Institute of Microstructure Technology, Karlsruhe Institute for Technology, 76131 Karlsruhe, Germany
3
Microfluidics Laboratory, Department of Industrial Engineering (DIN), University of Bologna, Via del Lazzaretto 15/5, 40131 Bologna BO, Italy
*
Author to whom correspondence should be addressed.
Micromachines 2020, 11(3), 323; https://doi.org/10.3390/mi11030323
Received: 27 February 2020 / Revised: 18 March 2020 / Accepted: 19 March 2020 / Published: 20 March 2020
Miniaturized heat exchangers are well known for their superior heat transfer capabilities in comparison to macro-scale devices. While in standard microchannel systems the improved performance is provided by miniaturized distances and very small hydraulic diameters, another approach can also be followed, namely, the generation of local turbulences. Localized turbulence enhances the heat exchanger performance in any channel or tube, but also includes an increased pressure loss. Shifting the critical Reynolds number to a lower value by introducing perturbators controls pressure losses and improves thermal efficiency to a considerable extent. The objective of this paper is to investigate in detail collector performance based on reduced-order modelling and validate the numerical model based on experimental observations of flow maldistribution and pressure losses. Two different types of perturbators, Wire-net and S-shape, were analyzed. For the former, a metallic wire mesh was inserted in the flow passages (hot and cold gas flow) to ensure stiffness and enhance microchannel efficiency. The wire-net perturbators were replaced using an S-shaped perturbator model for a comparative study in the second case mentioned above. An optimum mass flow rate could be found when the thermal efficiency reaches a maximum. Investigation of collectors with different microchannel configurations (s-shaped, wire-net and plane channels) showed that mass flow rate deviation decreases with an increase in microchannel resistance. The recirculation zones in the cylindrical collectors also changed the maldistribution pattern. From experiments, it could be observed that microchannels with S-shaped perturbators shifted the onset of turbulent transition to lower Reynolds number values. Experimental studies on pressure losses showed that the pressure losses obtained from numerical studies were in good agreement with the experiments (<4%). View Full-Text
Keywords: micro channel; reduced model; wire-net perturbators; s-shaped perturbators; high-temperature heat exchangers micro channel; reduced model; wire-net perturbators; s-shaped perturbators; high-temperature heat exchangers
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Joseph, J.; Rehman, D.; Delanaye, M.; Morini, G.L.; Nacereddine, R.; Korvink, J.G.; Brandner, J.J. Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution. Micromachines 2020, 11, 323.

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