Effect of entrainment on liquid film dryout in vertical upward annular flow

Zan Wu; Vishwas Wadekar; Bengt Sundén

doi:10.1115/HT2016-7042

Effect of entrainment on liquid film dryout in vertical upward annular flow

Zan Wu, Vishwas Wadekar, Bengt Sundén

Heat Transfer

University of Paris-Saclay

Research output: Chapter in Book/Report/Conference proceeding › Paper in conference proceeding › peer-review

Abstract

This work aims to investigate the effect of liquid entrainment on liquid film dryout in annular flow for flow boiling. Entrainment and deposition rates of droplets were included in mass conservation equations to estimate the local liquid film mass flux in annular flow, and the critical vapor quality at dryout conditions. Different entrainment rate correlations were evaluated using flow boiling data of npentane, iso-octane and water. Effect of the initial entrained fraction (IEF) at the churn-annular transition was also investigated. A transition Boiling number was proposed to separate the IEF-sensitive region at high Boiling numbers and the IEF-insensitive region low Boiling numbers. Besides, the diameter effect on dryout vapor quality was studied. The dryout vapor quality increases with decreasing tube diameter. A possible reason is that there is less droplet entrainment in smaller tubes, as evidenced in numerous flow pattern visualization studies. It needs to be pointed out that the dryout characteristics of submillimeter channels to be different because of different mechanisms of dryout, i.e., drying of liquid film underneath long vapor slugs and flow boiling instabilities.

Original language	English
Title of host publication	Heat Transfer in Multiphase Systems; Gas Turbine Heat Transfer; Manufacturing and Materials Processing; Heat Transfer in Electronic Equipment; Heat and Mass Transfer in Biotechnology; Heat Transfer Under Extreme Conditions; Computational Heat Transfer; Heat Transfer Visualization Gallery; General Papers on Heat Transfer; Multiphase Flow and Heat Transfer; Transport Phenomena in Manufacturing and Materials Processing
Publisher	American Society Of Mechanical Engineers (ASME)
Volume	2
ISBN (Electronic)	9780791850336
DOIs	https://doi.org/10.1115/HT2016-7042
Publication status	Published - 2016
Event	ASME 2016 Heat Transfer Summer Conference, HT 2016, collocated with the ASME 2016 Fluids Engineering Division Summer Meeting and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels - Washington, United States Duration: 2016 Jul 10 → 2016 Jul 14

Conference

Conference	ASME 2016 Heat Transfer Summer Conference, HT 2016, collocated with the ASME 2016 Fluids Engineering Division Summer Meeting and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels
Country/Territory	United States
City	Washington
Period	2016/07/10 → 2016/07/14

Subject classification (UKÄ)

Energy Engineering

Access to Document

10.1115/HT2016-7042

Cite this

Wu, Z., Wadekar, V., & Sundén, B. (2016). Effect of entrainment on liquid film dryout in vertical upward annular flow. In Heat Transfer in Multiphase Systems; Gas Turbine Heat Transfer; Manufacturing and Materials Processing; Heat Transfer in Electronic Equipment; Heat and Mass Transfer in Biotechnology; Heat Transfer Under Extreme Conditions; Computational Heat Transfer; Heat Transfer Visualization Gallery; General Papers on Heat Transfer; Multiphase Flow and Heat Transfer; Transport Phenomena in Manufacturing and Materials Processing (Vol. 2). Article HT2016-7042 American Society Of Mechanical Engineers (ASME). https://doi.org/10.1115/HT2016-7042

Wu, Zan ; Wadekar, Vishwas ; Sundén, Bengt. / Effect of entrainment on liquid film dryout in vertical upward annular flow. Heat Transfer in Multiphase Systems; Gas Turbine Heat Transfer; Manufacturing and Materials Processing; Heat Transfer in Electronic Equipment; Heat and Mass Transfer in Biotechnology; Heat Transfer Under Extreme Conditions; Computational Heat Transfer; Heat Transfer Visualization Gallery; General Papers on Heat Transfer; Multiphase Flow and Heat Transfer; Transport Phenomena in Manufacturing and Materials Processing. Vol. 2 American Society Of Mechanical Engineers (ASME), 2016.

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title = "Effect of entrainment on liquid film dryout in vertical upward annular flow",

abstract = "This work aims to investigate the effect of liquid entrainment on liquid film dryout in annular flow for flow boiling. Entrainment and deposition rates of droplets were included in mass conservation equations to estimate the local liquid film mass flux in annular flow, and the critical vapor quality at dryout conditions. Different entrainment rate correlations were evaluated using flow boiling data of npentane, iso-octane and water. Effect of the initial entrained fraction (IEF) at the churn-annular transition was also investigated. A transition Boiling number was proposed to separate the IEF-sensitive region at high Boiling numbers and the IEF-insensitive region low Boiling numbers. Besides, the diameter effect on dryout vapor quality was studied. The dryout vapor quality increases with decreasing tube diameter. A possible reason is that there is less droplet entrainment in smaller tubes, as evidenced in numerous flow pattern visualization studies. It needs to be pointed out that the dryout characteristics of submillimeter channels to be different because of different mechanisms of dryout, i.e., drying of liquid film underneath long vapor slugs and flow boiling instabilities.",

author = "Zan Wu and Vishwas Wadekar and Bengt Sund{\'e}n",

year = "2016",

doi = "10.1115/HT2016-7042",

language = "English",

volume = "2",

booktitle = "Heat Transfer in Multiphase Systems; Gas Turbine Heat Transfer; Manufacturing and Materials Processing; Heat Transfer in Electronic Equipment; Heat and Mass Transfer in Biotechnology; Heat Transfer Under Extreme Conditions; Computational Heat Transfer; Heat Transfer Visualization Gallery; General Papers on Heat Transfer; Multiphase Flow and Heat Transfer; Transport Phenomena in Manufacturing and Materials Processing",

publisher = "American Society Of Mechanical Engineers (ASME)",

address = "United States",

note = "ASME 2016 Heat Transfer Summer Conference, HT 2016, collocated with the ASME 2016 Fluids Engineering Division Summer Meeting and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels ; Conference date: 10-07-2016 Through 14-07-2016",

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Wu, Z, Wadekar, V & Sundén, B 2016, Effect of entrainment on liquid film dryout in vertical upward annular flow. in Heat Transfer in Multiphase Systems; Gas Turbine Heat Transfer; Manufacturing and Materials Processing; Heat Transfer in Electronic Equipment; Heat and Mass Transfer in Biotechnology; Heat Transfer Under Extreme Conditions; Computational Heat Transfer; Heat Transfer Visualization Gallery; General Papers on Heat Transfer; Multiphase Flow and Heat Transfer; Transport Phenomena in Manufacturing and Materials Processing. vol. 2, HT2016-7042, American Society Of Mechanical Engineers (ASME), ASME 2016 Heat Transfer Summer Conference, HT 2016, collocated with the ASME 2016 Fluids Engineering Division Summer Meeting and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels, Washington, United States, 2016/07/10. https://doi.org/10.1115/HT2016-7042

Effect of entrainment on liquid film dryout in vertical upward annular flow. / Wu, Zan; Wadekar, Vishwas; Sundén, Bengt.
Heat Transfer in Multiphase Systems; Gas Turbine Heat Transfer; Manufacturing and Materials Processing; Heat Transfer in Electronic Equipment; Heat and Mass Transfer in Biotechnology; Heat Transfer Under Extreme Conditions; Computational Heat Transfer; Heat Transfer Visualization Gallery; General Papers on Heat Transfer; Multiphase Flow and Heat Transfer; Transport Phenomena in Manufacturing and Materials Processing. Vol. 2 American Society Of Mechanical Engineers (ASME), 2016. HT2016-7042.

Research output: Chapter in Book/Report/Conference proceeding › Paper in conference proceeding › peer-review

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T1 - Effect of entrainment on liquid film dryout in vertical upward annular flow

AU - Wu, Zan

AU - Wadekar, Vishwas

AU - Sundén, Bengt

PY - 2016

Y1 - 2016

N2 - This work aims to investigate the effect of liquid entrainment on liquid film dryout in annular flow for flow boiling. Entrainment and deposition rates of droplets were included in mass conservation equations to estimate the local liquid film mass flux in annular flow, and the critical vapor quality at dryout conditions. Different entrainment rate correlations were evaluated using flow boiling data of npentane, iso-octane and water. Effect of the initial entrained fraction (IEF) at the churn-annular transition was also investigated. A transition Boiling number was proposed to separate the IEF-sensitive region at high Boiling numbers and the IEF-insensitive region low Boiling numbers. Besides, the diameter effect on dryout vapor quality was studied. The dryout vapor quality increases with decreasing tube diameter. A possible reason is that there is less droplet entrainment in smaller tubes, as evidenced in numerous flow pattern visualization studies. It needs to be pointed out that the dryout characteristics of submillimeter channels to be different because of different mechanisms of dryout, i.e., drying of liquid film underneath long vapor slugs and flow boiling instabilities.

AB - This work aims to investigate the effect of liquid entrainment on liquid film dryout in annular flow for flow boiling. Entrainment and deposition rates of droplets were included in mass conservation equations to estimate the local liquid film mass flux in annular flow, and the critical vapor quality at dryout conditions. Different entrainment rate correlations were evaluated using flow boiling data of npentane, iso-octane and water. Effect of the initial entrained fraction (IEF) at the churn-annular transition was also investigated. A transition Boiling number was proposed to separate the IEF-sensitive region at high Boiling numbers and the IEF-insensitive region low Boiling numbers. Besides, the diameter effect on dryout vapor quality was studied. The dryout vapor quality increases with decreasing tube diameter. A possible reason is that there is less droplet entrainment in smaller tubes, as evidenced in numerous flow pattern visualization studies. It needs to be pointed out that the dryout characteristics of submillimeter channels to be different because of different mechanisms of dryout, i.e., drying of liquid film underneath long vapor slugs and flow boiling instabilities.

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M3 - Paper in conference proceeding

AN - SCOPUS:85002843340

VL - 2

BT - Heat Transfer in Multiphase Systems; Gas Turbine Heat Transfer; Manufacturing and Materials Processing; Heat Transfer in Electronic Equipment; Heat and Mass Transfer in Biotechnology; Heat Transfer Under Extreme Conditions; Computational Heat Transfer; Heat Transfer Visualization Gallery; General Papers on Heat Transfer; Multiphase Flow and Heat Transfer; Transport Phenomena in Manufacturing and Materials Processing

PB - American Society Of Mechanical Engineers (ASME)

T2 - ASME 2016 Heat Transfer Summer Conference, HT 2016, collocated with the ASME 2016 Fluids Engineering Division Summer Meeting and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels

Y2 - 10 July 2016 through 14 July 2016

ER -

Wu Z, Wadekar V, Sundén B. Effect of entrainment on liquid film dryout in vertical upward annular flow. In Heat Transfer in Multiphase Systems; Gas Turbine Heat Transfer; Manufacturing and Materials Processing; Heat Transfer in Electronic Equipment; Heat and Mass Transfer in Biotechnology; Heat Transfer Under Extreme Conditions; Computational Heat Transfer; Heat Transfer Visualization Gallery; General Papers on Heat Transfer; Multiphase Flow and Heat Transfer; Transport Phenomena in Manufacturing and Materials Processing. Vol. 2. American Society Of Mechanical Engineers (ASME). 2016. HT2016-7042 doi: 10.1115/HT2016-7042

Effect of entrainment on liquid film dryout in vertical upward annular flow

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