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Numerical investigation of heat transfer in a CO2 two-phase ejector

Abstract

In this paper, the influence of heat transfer in the walls of an R744 two-phase ejector on ejector performance was investigated. A numerical investigation was performed using a computational fluid dynamic (CFD) model of the R744 two-phase flow coupled with the heat transfer inside the ejector. An ejector equipped with thermocouple channels was designed and manufactured to investigate temperature distribution in the inner walls under boundary conditions typical for a refrigeration and air-conditioning application in a supermarket. The ejector was installed on the test rig to perform a test series that evaluated the outer walls of the ejector with and without insulation. The experimental results were used to validate the proposed CFD model, and a numerical investigation was performed to analyse the influence of heat transfer on ejector performance. The motive nozzle and suction nozzle mass flow rates accuracies were within ±7% and ±15%, respectively. In addition, the proposed CFD model predicted the wall temperatures with ±5 K accuracy for most of the validated points. The heat transfer coefficient of the R744 two-phase flow inside the ejector is presented. The non-adiabatic inner walls degraded ejector performance. The maximum reduction of the mass entrainment ratio reached approximately 13%. © 2018 Elsevier Ltd. All rights reserved
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Category

Academic article

Client

  • Research Council of Norway (RCN) / 244009

Language

English

Author(s)

  • Michal Haida
  • Jacek Smolka
  • Armin Hafner
  • Mikolaj Mastrowski
  • Michal Palacz
  • Kenneth B. Madsen
  • Andrzej J. Nowak
  • Krzysztof Banasiak

Affiliation

  • Silesian University of Technology
  • Norwegian University of Science and Technology
  • Danfoss Drives AS
  • SINTEF Energy Research / Termisk energi

Year

2018

Published in

Energy

ISSN

0360-5442

Publisher

Elsevier

Volume

163

Page(s)

682 - 698

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