Consolidated methodology to predicting flow boiling critical heat flux for inclined channels in Earth gravity and for microgravity

Kharangate, Chirag R.; Konishi, Christopher; Mudawar, Issam

doi:10.1016/j.ijheatmasstransfer.2015.08.018

Cited by 25 publications

(8 citation statements)

References 37 publications

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“…In an effort to complement previous studies conducted as part of the ongoing project between PU-BTPFL and NASA GRC dealing primarily with characterization and prediction of important time-averaged design parameters such as heat transfer coefficient [44][45][46][47], pressure drop [31,[48][49], and CHF [50][51][52][53], the present study will also present and evaluate several flow boiling stability maps commonly found in literature.…”

Section: (2)mentioning

confidence: 99%

Experimental investigation into the impact of density wave oscillations on flow boiling system dynamic behavior and stability

O’Neill

Mudawar

Hasan

et al. 2018

International Journal of Heat and Mass Transfer

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In order to better understand and quantify the effect of instabilities in systems utilizing flow boiling heat transfer, the present study explores dynamic results for pressure drop, mass velocity, thermodynamic equilibrium quality, and heated wall temperature to ascertain and analyze the dominant modes in which they oscillate. Flow boiling experiments are conducted for a range of mass velocities with both subcooled and saturated inlet conditions in vertical upflow, vertical downflow, and horizontal flow orientations. High frequency pressure measurements are used to investigate the influence of individual flow loop components (flow boiling module, pump, preheater, condenser, etc.) on dynamic behavior of the fluid, with fast Fourier transforms of the same used to provide critical frequency domain information. Conclusions from this analysis are used to isolate instabilities present within the system due to physical interplay between thermodynamic and hydrodynamic effects. Parametric analysis is undertaken to better understand the conditions under which these instabilities form and their impact on system performance. Several prior stability maps are presented, with new stability maps provided to better address contextual trends discovered in the present study.

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Section: (2)mentioning

confidence: 99%

Experimental investigation into the impact of density wave oscillations on flow boiling system dynamic behavior and stability

O’Neill

Mudawar

Hasan

et al. 2018

International Journal of Heat and Mass Transfer

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“…The current study deals with flow boiling and augments prior work dealing with experimental investigation and prediction of key design parameters including heat transfer coefficient [86][87][88][89], pressure drop [53,[90][91], and critical heat flux [92][93][94][95][96][97][98], with development of a mechanistic model for prediction of frequency and amplitude of DWO induced pressure oscillations evident in vertical upflow boiling with finite inlet quality.…”

Section: Objectives Of Studymentioning

confidence: 99%

Mechanistic model to predict frequency and amplitude of Density Wave Oscillations in vertical upflow boiling

O’Neill

Mudawar

2018

International Journal of Heat and Mass Transfer

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Modeling of two-phase flow transient behavior and instabilities has traditionally been one of the more challenging endeavors in heat transfer research due to the need to distinguish between a wide range of instability modes systems can manifest depending on differences in operating conditions, as well as the difficulty in experimentally determining key characteristics of these phenomena. This study presents a new mechanistic model for Density Wave Oscillations (DWOs) in vertical upflow boiling using conclusions drawn from analysis of flow visualization images and transient experimental results as a basis from which to begin modeling. Counter to many prior studies attributing DWOs to feedback effects between flow rate, pressure drop, and flow enthalpy causing oscillations in position of the bulk boiling boundary, the present instability mode stems primarily from body force acting on liquid and vapor phases in a separated flow regime leading to liquid accumulation in the near-inlet region of the test section, which eventually departs and moves along the channel, acting to re-wet liquid film along the channel walls and re-establish annular, cocurrent flow. This process was modeled by dividing the test section into three distinct control volumes and solving transient conservation equations for each, yielding predictions of frequencies at which this process occurs as well as amplitude of associated pressure oscillations. Values for these parameters were validated against an experimental database of 236 FC-72 points and show the model provides good predictive accuracy and capably captures the influence of parametric changes to operating conditions.

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“…(2). The outer smooth side of the heated plate of the minichannel was strengthened on both sides with narrow micanite panels (8) to prevent the plate surface from deforming.…”

Section: Experimental Standmentioning

confidence: 99%

“…Research reported in the literature finds that different orientation of test sections is an important factor in flow boiling heat transfer models in mini spaces. In [8], the researchers examine complex trends of flow boiling critical heat flux (CHF) in a rectangular channel at eight angular positions (0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°) in both microgravity and Earth gravity. The authors reported that CHF sensitivity to orientation was lower for upflow and upward-facing heated wall positions (0°-90°) and higher for downward flow and downward-facing wall positions (180° -270°).…”

Section: Introductionmentioning

confidence: 99%

Research on flow boiling heat transfer for vertical upward and downward flows along a minichannel with a smooth heated surface

Strąk

Piasecka

2018

E3S Web Conf.

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The paper reports results for flow boiling heat transfer in a 1.7 mm deep minichannel vertically-oriented with upward and downward flow. The heated element for HFE-649 flowing upward or downward in a channel was a smooth plate. Infrared thermography allowed determining changes in temperature on the outer plate side. Two-phase flow structures were recorded through a glass pane at the other side of the channel being in contact with the fluid. Analysis of the results was performed on the basis of experimental series obtained for the same heat flux for upward and downward flows and two mass flow velocities. The results are presented as relationships between the heat transfer coefficient or the plate temperature and the channel length, boiling curves, and between the heat flux and the heat transfer coefficient and two-phase flow structure images. The impact of mass flow velocity on the heat transfer coefficient and two-phase flow structures for vertical upward and downward flows were discussed.

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Consolidated methodology to predicting flow boiling critical heat flux for inclined channels in Earth gravity and for microgravity

Cited by 25 publications

References 37 publications

Experimental investigation into the impact of density wave oscillations on flow boiling system dynamic behavior and stability

Experimental investigation into the impact of density wave oscillations on flow boiling system dynamic behavior and stability

Mechanistic model to predict frequency and amplitude of Density Wave Oscillations in vertical upflow boiling

Research on flow boiling heat transfer for vertical upward and downward flows along a minichannel with a smooth heated surface

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