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Geometrical optimization of a steam jet-ejector using the computational fluid dynamics

Darbandi, M ; Sharif University of Technology | 2018

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  1. Type of Document: Article
  2. DOI: 10.1115/FEDSM2018-83203
  3. Publisher: American Society of Mechanical Engineers (ASME) , 2018
  4. Abstract:
  5. The vacuum systems play crucial role in various industries including, but not limited to, power generation, refrigeration, desalination, and aerospace engineering. There are different types of vacuum systems. Among them, the ejector or vacuum pump is highly utilized due to its low capital cost and easy maintenance. Generally, the better operation of a vacuum system can dramatically affect the performance of its upper-hand systems, e.g., the general efficiency of a thermal power plant cycle. This can be achieved if such vacuum systems are correctly designed, implemented, and operated. The focus of this work is on an existing steam jet-ejector, whose primary flow is a high pressure superheated steam and the suction flow is a mixture of steam and air. The main goal of this work is to optimize the geometry of the ejector including the nozzle exit position (NXP), the primary nozzle diverging angle, and the secondary throat length, etc. From the computational fluid dynamics perspective, there are some major challenges to simulate this ejector. It requires predicting the correct turbulent fluid flow and heat transfer phenomena with great complexities in treating the mixed subsonic and supersonic flow regimes, very high and very low pressure regions adjacent to each other, and complex mixing two phase flow jets. Indeed, the latter one has been almost neglected in literature. The main concern of this study is to reduce the consumption of motive steam, i.e., to increase the entrainment ratio via modifying the ejector geometry and investigating its performance under different operating conditions that helps to save the water consumption. Copyright © 2018 ASME
  6. Keywords:
  7. Air ejectors ; Computational fluid dynamics ; Computational geometry ; Costs ; Desalination ; Ejectors (pumps) ; Fluid mechanics ; Heat transfer ; Nozzles ; Steam ; Supersonic aerodynamics ; Thermoelectric power plants ; Different operating conditions ; Entrainment ratio ; General efficiencies ; Geometrical optimization ; Steam jet ejectors ; Superheated steam ; Thermal power plants ; Turbulent fluid flow ; Two phase flow
  8. Source: ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting, FEDSM 2018, 15 July 2018 through 20 July 2018 ; Volume 2 , 2018 ; 08888116 (ISSN); 9780791851562 (ISBN)
  9. URL: https://asmedigitalcollection.asme.org/FEDSM/proceedings-abstract/FEDSM2018/51562/V002T11A006/272085