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Advanced heat transfer analysis of a U-shaped pulsating heat pipe considering evaporative liquid film trailing from its liquid slug

Nemati, R ; Sharif University of Technology | 2018

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  1. Type of Document: Article
  2. DOI: 10.1016/j.applthermaleng.2018.04.064
  3. Publisher: Elsevier Ltd , 2018
  4. Abstract:
  5. In order to study the heat transfer mechanism and predict the heat transfer capability of a pulsating heat pipe (PHP), a numerical model was used to simulate the oscillating behavior of liquid slug considering liquid film thickness in the evaporator and reduction of liquid film thickness due to evaporation. In this article, thermal performance of an open loop closed end PHP of copper with a diameter of 1 mm and various working fluids including water (DW) and ethanol was investigated. The governing equations of mass, momentum, and energy equations were solved for liquid slug and vapor plugs. The results showed that by considering liquid film thickness behind the liquid slug, for both the water (DW) and ethanol, oscillating amplitude of liquid slug increases and its frequency decreases. Under similar conditions, the ethanol-based fluid exhibited larger oscillation amplitude and higher latent heat transfer, as compared to the water-based fluid. For the water and ethanol-based fluids, 98% and 94% of the total heat was transferred as sensible heat through the liquid slug, respectively while the remaining was transferred as latent heat. © 2018 Elsevier Ltd
  6. Keywords:
  7. Liquid film evaporation ; Variable liquid film thickness ; Ethanol ; Evaporation ; Film thickness ; Heat pipes ; Latent heat ; Liquid films ; Oscillating flow ; Film evaporation ; Heat transfer analysis ; Heat transfer capability ; Heat transfer mechanism ; Numerical solution ; Oscillating amplitudes ; Oscillation amplitude ; Pulsating heat pipe ; Heat transfer
  8. Source: Applied Thermal Engineering ; Volume 138 , 28 June , 2018 , Pages 475-489 ; 13594311 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/pii/S1359431117373040