Study of vapor film dynamics and heat transfer through an image processing technique

Faith Beck, Nurali Virani, Lokanath Mohanta, Faruk A. Sohag, Asok Ray, Fan-bill B. Cheung

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Understanding of two-phase heat transfer mechanisms on downward-facing hemispherical vessels is crucial during external reactor vessel cooling (ERVC) under severe accident conditions. Film boiling is the predominant heat transfer regime in the initial stages of quenching under these circumstances. In this work, the process of downward-facing film boiling on the outer surface of a hemispherical vessel is studied using high-speed video. High-speed video is a valuable measurement technique because it does not require any invasive sensors that may alter the natural liquid-vapor interface in film boiling. With high-speed video and a few image processing techniques, accurate measurements of film thickness have been made at four different degrees of subcooling (0, 3, 5, and 10 °C) and angular locations (0, 14, 28, and 42°) on a hemispherical vessel. With increasing subcooling and decreasing angular location, the vapor film thickness has been found to decrease. Average film thickness at 0 °C (respectively, 10 °C) subcooling and one second after immersion is found to be approximately 2 mm (respectively, 0.5 mm). High-speed videos taken at 650 frames per second (fps) have shown significant oscillations at the liquid-vapor interface during film boiling. Additionally, oscillations in the film thickness and its wave characteristics have been analyzed at the prescribed angular locations and degrees of subcooling. From the visual data, insights regarding the heat transfer behavior of film boiling are obtained. Additionally, the characteristics of the interfacial oscillations have been related to the heat flux distribution. The mechanism for the interfacial oscillations can be attributed to disturbances in the balance between the wall and interfacial heat fluxes, along with the hydrodynamic instability.

Original languageEnglish (US)
Pages (from-to)1310-1320
Number of pages11
JournalInternational Journal of Heat and Mass Transfer
Volume125
DOIs
StatePublished - Oct 1 2018

Fingerprint

film boiling
Boiling liquids
image processing
Image processing
heat transfer
Vapors
vessels
Film thickness
vapors
Heat transfer
film thickness
high speed
Facings
oscillations
liquid-vapor interfaces
Heat flux
heat flux
Liquids
accidents
submerging

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

Cite this

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title = "Study of vapor film dynamics and heat transfer through an image processing technique",
abstract = "Understanding of two-phase heat transfer mechanisms on downward-facing hemispherical vessels is crucial during external reactor vessel cooling (ERVC) under severe accident conditions. Film boiling is the predominant heat transfer regime in the initial stages of quenching under these circumstances. In this work, the process of downward-facing film boiling on the outer surface of a hemispherical vessel is studied using high-speed video. High-speed video is a valuable measurement technique because it does not require any invasive sensors that may alter the natural liquid-vapor interface in film boiling. With high-speed video and a few image processing techniques, accurate measurements of film thickness have been made at four different degrees of subcooling (0, 3, 5, and 10 °C) and angular locations (0, 14, 28, and 42°) on a hemispherical vessel. With increasing subcooling and decreasing angular location, the vapor film thickness has been found to decrease. Average film thickness at 0 °C (respectively, 10 °C) subcooling and one second after immersion is found to be approximately 2 mm (respectively, 0.5 mm). High-speed videos taken at 650 frames per second (fps) have shown significant oscillations at the liquid-vapor interface during film boiling. Additionally, oscillations in the film thickness and its wave characteristics have been analyzed at the prescribed angular locations and degrees of subcooling. From the visual data, insights regarding the heat transfer behavior of film boiling are obtained. Additionally, the characteristics of the interfacial oscillations have been related to the heat flux distribution. The mechanism for the interfacial oscillations can be attributed to disturbances in the balance between the wall and interfacial heat fluxes, along with the hydrodynamic instability.",
author = "Faith Beck and Nurali Virani and Lokanath Mohanta and Sohag, {Faruk A.} and Asok Ray and Cheung, {Fan-bill B.}",
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Study of vapor film dynamics and heat transfer through an image processing technique. / Beck, Faith; Virani, Nurali; Mohanta, Lokanath; Sohag, Faruk A.; Ray, Asok; Cheung, Fan-bill B.

In: International Journal of Heat and Mass Transfer, Vol. 125, 01.10.2018, p. 1310-1320.

Research output: Contribution to journalArticle

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AU - Beck, Faith

AU - Virani, Nurali

AU - Mohanta, Lokanath

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AU - Ray, Asok

AU - Cheung, Fan-bill B.

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N2 - Understanding of two-phase heat transfer mechanisms on downward-facing hemispherical vessels is crucial during external reactor vessel cooling (ERVC) under severe accident conditions. Film boiling is the predominant heat transfer regime in the initial stages of quenching under these circumstances. In this work, the process of downward-facing film boiling on the outer surface of a hemispherical vessel is studied using high-speed video. High-speed video is a valuable measurement technique because it does not require any invasive sensors that may alter the natural liquid-vapor interface in film boiling. With high-speed video and a few image processing techniques, accurate measurements of film thickness have been made at four different degrees of subcooling (0, 3, 5, and 10 °C) and angular locations (0, 14, 28, and 42°) on a hemispherical vessel. With increasing subcooling and decreasing angular location, the vapor film thickness has been found to decrease. Average film thickness at 0 °C (respectively, 10 °C) subcooling and one second after immersion is found to be approximately 2 mm (respectively, 0.5 mm). High-speed videos taken at 650 frames per second (fps) have shown significant oscillations at the liquid-vapor interface during film boiling. Additionally, oscillations in the film thickness and its wave characteristics have been analyzed at the prescribed angular locations and degrees of subcooling. From the visual data, insights regarding the heat transfer behavior of film boiling are obtained. Additionally, the characteristics of the interfacial oscillations have been related to the heat flux distribution. The mechanism for the interfacial oscillations can be attributed to disturbances in the balance between the wall and interfacial heat fluxes, along with the hydrodynamic instability.

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