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Abstract
The objective of this article is to analyze complex micro-channels with wire-net and S-shaped perturbators and implement a reduced order modeling (ROM) approach to assess the entire heat exchanger performance and validate through experiments. Shifting the critical Reynolds number to lower values using perturbators decreases the pressure losses and enhance the thermal efficiency. There is an optimum mass flow (for both perturbators) where the thermal efficiency reaches maximum. The thermal efficiency of the wire-net perturbator is relatively high compared to S-shaped perturbators. The S-shaped perturbators induces strong wall-normal velocity fluctuations and enhances the heat transfer. Furthermore, the turbulence production term provides a deeper insight into flow attachment and detachment near the wire net intersections. The computational fluid dynamics approach (conjugate heat transfer models and ROM) was introduced to reduce the computational grid size and predict the collector performance. The secondary collector performance is determined by considering the microchannels as porous mediums. Apparently, the primary collector performance is determined by considering both secondary collectors and microchannels as porous mediums. The cylindrical secondary collectors contribute nearly 40–50% of the pressure drop. Experimental validation showed that the ROM predicts the heat exchanger performance with a good (<4.4%) accuracy.
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Notes on contributors
Jojomon Joseph
Jojomon Joseph is currently working as an Early Stage Researcher in Mitis, Belgium and is a Ph.D. student in the Institute of Microstructure Technology of Karlsruhe Institute of Technology, Germany. He received his M.Sc. in turbulence, a joint master’s program by Ecole Centrale de Lille, Ecole Nationale Supérieure de Mécanique et d'Aérotechnique de Poitiers and Ecole Nationale Supérieure d'Ingénieurs de Poitiers, France. His research is focused on numerical modeling and experimental investigation of turbulence influence on heat transfer characteristics for low Reynolds number flows. His research also includes microfabrication of microchannels using 3D printing techniques. He is also a part of MIGRATE (MIniaturized Gas flow foR Applications with enhanced Thermal Effects), Innovative Training Network.
Michel Delanaye
Michel Delanaye is the founder of MITIS SA, a startup company located in Liège (Belgium) specialized in the development of clean distributed small cogeneration systems. He holds a Ph.D. in Mechanical Engineering from the University of Liège in the area of computational fluid dynamics with emphasis on aerodynamics. He was awarded a Fulbright grant, NATO postdoctoral fellowship and US National Research Council Associate position at NASA Ames Research Council from 1996 to 1999. He had positions at NUMECA Int as R&D engineer and general manager at Cenaero. He is also the founder of GeonX SA, a startup company developing software in the field of virtual manufacturing, acquired in 2017 by General Electric.
Rabia Nacereddine
Rabia Nacereddine is currently working as a Research Engineer in Mitis, Belgium. He completed his Post-Doc in 2012, on optimization of the heat exchanger performance from Ecole des Mines de Douai, France. He completed his Ph.D. in fluid mechanics and heat transfer from Université Joseph Fourier-Grenoble, France (2007). He worked on turbulence generations mechanisms for his PhD. His research is on improving the heat transfer by passives methods, using CFD approach. Apart from this, he also deals with the design of the micro-CHP system: the design of the heat exchanger, the flameless combustion chamber, the micro-compressor, and the micro-turbine.
Andres Giraldo
Andres Giraldo is currently working as a design engineer at MITIS SA in Belgium. He received his M.Sc. in turbomachines at the Royal Institute of Technology in Sweden and the University of Liege in Belgium. His work is focused on the development of micro-gas turbines for residential applications.
Mehdi Rouabah
Mehdi Rouabah is currently working as research engineer in Mitis SA Belgium and enrolled as a Ph.D. student at the Free University of Brussels, Belgium. He received his master’s degree in fluids and energetics applications from the University of Khemis Miliana, Algeria. He worked as a research engineer in FIMA (Laboratory of industrial fluids, measurements and applications) after he joined a consultancy company specializing on hospital construction. Currently, he works on the design, development, and optimization of flameless combustion chambers for micro CHP applications (validation of numerical studies by experimental testing). In addition, he also works on advanced brazing techniques to develop cost-effective heat exchangers.
Jan G. Korvink
Jan G. Korvink received the M.Sc. degree in mechanical engineering (specializing in computational mechanics) from the University of Cape Town, South Africa, in 1987, and the Ph.D. degree from ETH Zurich, Switzerland, in 1993. He joined the University of Freiburg, Germany, as a Full Professor of Microsystems Engineering, where he co-directed the Freiburg Institute for Advanced Studies. In 2015, he joined the Karlsruhe Institute of Technology, where besides directing the Institute of Microstructure Technology, he also acts as a Speaker of the Helmholtz Research Program in the Science and Technology of Nanosystems. He is also a co-founder of two successful startup companies. He has authored or coauthored more than 200 technical publications in the broad area of microsystems. His research interests include the development of ultra-low-cost micro manufacturing methods, micro system applications in the area of magnetic resonance imaging, and the design and simulation of micro- and nanosystems. He was a recipient of the Red Dot Design Concept Award in 2011 and the European Research Council Advanced Grant in the area of micro NMR metabolomics for the nematode C. elegans. He is a Founding Editor of the Advanced Micro and Nanosystems.
Juergen J. Brandner
Juergen J. Brandner is currently head of a research group at the Institute of Microstructure Technology of Karlsruhe Institute of Technology (KIT), Germany. He is dealing with design and manufacturing as well as thermal management of microscale devices. Aside, development and integration of miniaturized sensors into microfluidic devices and NMR/MRI applications to thermal, chemical, and biochemical processes in micro devices are in his interests. After studies in Chemistry, he obtained a diploma in Electrical Engineering, and an Engineering Doctorate in Mechanical Engineering, both from KIT. He also holds a Habilitation and Professorship (hon) in Micro Process Engineering from Technical University of Dresden. He is Lecturer at KIT and coordinating the Marie-Curie-ITN “MIGRATE.”