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Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution

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 follo...

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Autores principales: Joseph, Jojomon, Rehman, Danish, Delanaye, Michel, Morini, Gian Luca, Nacereddine, Rabia, Korvink, Jan G., Brandner, Juergen J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142721/
https://www.ncbi.nlm.nih.gov/pubmed/32244961
http://dx.doi.org/10.3390/mi11030323
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author Joseph, Jojomon
Rehman, Danish
Delanaye, Michel
Morini, Gian Luca
Nacereddine, Rabia
Korvink, Jan G.
Brandner, Juergen J.
author_facet Joseph, Jojomon
Rehman, Danish
Delanaye, Michel
Morini, Gian Luca
Nacereddine, Rabia
Korvink, Jan G.
Brandner, Juergen J.
author_sort Joseph, Jojomon
collection PubMed
description 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%).
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spelling pubmed-71427212020-04-15 Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution Joseph, Jojomon Rehman, Danish Delanaye, Michel Morini, Gian Luca Nacereddine, Rabia Korvink, Jan G. Brandner, Juergen J. Micromachines (Basel) Article 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%). MDPI 2020-03-20 /pmc/articles/PMC7142721/ /pubmed/32244961 http://dx.doi.org/10.3390/mi11030323 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Joseph, Jojomon
Rehman, Danish
Delanaye, Michel
Morini, Gian Luca
Nacereddine, Rabia
Korvink, Jan G.
Brandner, Juergen J.
Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution
title Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution
title_full Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution
title_fullStr Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution
title_full_unstemmed Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution
title_short Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution
title_sort numerical and experimental study of microchannel performance on flow maldistribution
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142721/
https://www.ncbi.nlm.nih.gov/pubmed/32244961
http://dx.doi.org/10.3390/mi11030323
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