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Evaporative two-phase flow modelling along a heated wall.

Modélisation d’un écoulement diphasique évaporatif le long d’une paroi chauffée.

Author(s) : RAOULT F.

Type of monograph: Doctoral thesis

Summary

Water sprays can boost air cooling capacity and improve the heat exchange between the air and the heat exchanger wall. A simple and accurate CFD model for two-phase flow studies with complex 3D geometries such as in heat exchangers remains challenging. This study is therefore carried out to fill this gap by developing a numerical tool to investigate the effects of the water spray on the heat exchanger efficiency. A spray model was developed to simulate droplet dispersion and evaporation. This model couples a 0D spray formation model with a 3D-CFD model. The Code_Saturne software is used and based on the Eulerian approach which requires less computer resources compared to Lagrangian one. The global model was compared with experimental results and through parametric analysis; the obtained results were consistent with the literature. It was also observed that droplets evaporate more during spray formation compared to the dispersion. Moreover, the optimum target cooling can be achieved when the spray surface is close to the target surface together with fast droplet evaporation rate. The effect of water sprays on a heated plate was also studied experimentally and numerically. An experiment was performed to study spray/wall interaction by using a heated plate located in a two-phase flow. For the numerical study, the water mass flow rate was determined by the normal velocity component to the wall. The formulation of boundary condition for droplet deposit and heat exchange on the wall is then obtained. The numerical and experimental results were compared and showed good agreement. Therefore, the spray model developed in this study on the heated plate is very promising.

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Pages: 249 p.

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Details

  • Original title: Modélisation d’un écoulement diphasique évaporatif le long d’une paroi chauffée.
  • Record ID : 30032282
  • Languages: French
  • Subject: Technology
  • Publication: Sorbonne Université - Antony - France
  • Publication date: 2019/01/31

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