Contribution à l'étude d'un évaporateur en graphite à ailettes spiralées internes

Abstract : This work is devoted to the experimental study, the modelling and the numerical simulation of hydrodynamic and thermal performances of a graphite evaporator with internal spiral fins. First, a global modelling, methodology have been developed to study the film flow with a Chemical Engineering Residence Time, Distribution (RTD) method. It appears that in spite of the complex structured heating surface, no atypical behaviour likely to decrease thermal performances have been detected such as short-circuit or dead zone. The mean residence time is closely represented by a power law model including operating parameters and geometrical parameters. Then, the thermal performances study led us to build a model describing the influence of these parameters in the case of water evaporation. This model was validated for the prediction of performance in the case of a Lithium Bromide aqueous solution evaporation. The design of an industrial apparatus exhibits advantages of this kind of evaporator for operating cost and raw material consumption reduction. A numerical approach is finally used to de scribe the local film flow using a commercial CFD software (FLUENT®). This software first describes a film flow over a succession of straight stair cases with a good agreement and gives the local evolution of the heat transfer coefficient. 3D film flow description exhibits a gravity to inertial transition in the mass flow rate range studied which corroborate some RTD hydrodynamic study conclusions.
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Theses
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http://docnum.univ-lorraine.fr/prive/INPL_T_2000_BESSENET_S.pdf
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https://hal.univ-lorraine.fr/tel-01750384
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Submitted on : Thursday, March 29, 2018 - 12:44:20 PM
Last modification on : Thursday, January 31, 2019 - 1:27:53 AM

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Sébastien Bessenet. Contribution à l'étude d'un évaporateur en graphite à ailettes spiralées internes. Alimentation et Nutrition. Institut National Polytechnique de Lorraine, 2000. Français. ⟨NNT : 2000INPL125N⟩. ⟨tel-01750384⟩

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