GAS FLOWS WITH HEAT TRANSFER IN MICRO CHANNELS: CLARIFICATIONS ABOUT THE NUSSELT NUMBER
| Autor: | Eric Chénier, Guy Lauriat, Xavier Nicolas, Chahinez Tchekiken |
|---|---|
| Přispěvatelé: | Nicolas, Xavier, Laboratoire de Modélisation et Simulation Multi Echelle (MSME), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris-Est Marne-la-Vallée (UPEM), Université Paris-Est Marne-la-Vallée (UPEM)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS) |
| Předmět: |
micro-channel
02 engineering and technology Slip (materials science) 01 natural sciences 010305 fluids & plasmas Physics::Fluid Dynamics viscous stress power 0103 physical sciences Thermal [PHYS.MECA.MEFL] Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] first order slip model [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Mechanics of the fluids [physics.class-ph] Chemistry gas flow Mechanics 021001 nanoscience & nanotechnology Nusselt number Forced convection Classical mechanics Heat flux Heat transfer Compressibility Knudsen number 0210 nano-technology |
| Zdroj: | HAL Scopus-Elsevier Proceedings of CHT-17 CHT17-ICHMT International Symposium on Advances in Computational Heat Transfer CHT17-ICHMT International Symposium on Advances in Computational Heat Transfer, May 2017, Napoli, Italy |
| Popis: | International audience; This paper deals with the modelling of weakly rarefied and dilute gas flows in heated micro channels by the continuum approach, valid for Knudsen numbers smaller than about 0.1. The first order slip and thermal jump model usually used for the forced convection of gas flows in long micro channels between two infinite plates is discussed. Indeed, in the huge literature related to this subject, it appears that simplified models are often used without justifying them and recurrent errors propagate from one paper to the other. The erroneous models particularly concern the heat transfer analysis and the energy equation. The compatibility of the pressure work and viscous dissipation in the energy equation with the power of the viscous forces at the walls and the choice of an appropriate Nusselt number are particularly discussed. Our aim is to provide a consistent model for gaseous micro-flows and the linked heat transfer. Then, a dimensional and asymptotic analysis is performed in the context of long micro channels. An analytical solution for the temperature field and the Nusselt number is proposed in the case of a compressible gas flow in a long micro-channel maintained at a constant wall temperature. This solution is compared with the numerical solution of the full model taking into account the first order slip and thermal jump conditions at the walls, the power of the viscous forces in the wall heat flux, the thermal creep term, the pressure work and the viscous dissipation in the bulk. The vanishing values of the Nusselt number measured in the experiments by Demsis et al. (2009, 2010) are explained for the first time. |
| Databáze: | OpenAIRE |
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