Gravity Scaling Parameter for Pool Boiling Heat Transfer

Raj, Rishi; Kim, Jungho; McQuillen, John

doi:10.1115/1.4001632

Cited by 28 publications

(7 citation statements)

References 11 publications

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“…The study of Macro et al (Di Marco and Grassi, 2002) about pool boiling under different gravitational accelerations showed that bubbles became smaller at high gravity, and they grew bigger at low gravity. Similar results could also be found in the simulation by Ma et al (2017) and experiments by Raj et al (2010). Besides, the gravity influences on CHF have also been studied in previous research studies (Raj et al, 2010;Ma et al, 2017;Fang et al, 2019), and the results showed that higher gravity within a certain range could increase CHF.…”

Section: Introductionsupporting

confidence: 84%

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Numerical Investigation of Pool Boiling Under Ocean Conditions with Lattice Boltzmann Simulation. Part Ⅰ: Heaving Condition

Zou

Liu

et al. 2021

Front. Energy Res.

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Pool boiling is the heat-transfer mechanism of many heat exchangers inside ocean nuclear power plants working under the complex marine circumstances. Also, ocean conditions will create a new acceleration field other than gravity for the fluid, which induces some unique thermal–hydraulic characteristics. In this study, pool boiling under heaving conditions is numerically simulated using multiple relaxation time phase change lattice Boltzmann method. Firstly, the simulated results under static condition have been validated with recognized empirical equations, such as Rohsenow’s correlation at nucleate boiling, Zuber’s model, and Kandlikar’s model about critical heat flux (CHF). Then, pool boiling patterns, the boiling curve of time-averaged heat flux, transient heat flux, and heaving effects on different pool boiling regions are investigated. The results show that pool boiling curves of time-averaged heat flux between heaving conditions and static conditions with middle superheat degrees are similar. Heat transfer under heaving conditions at low superheat is somewhat enhanced, and it is weakened at high superheat, which leads to a slightly smaller critical heat flux with larger superheat compared with that under static conditions. Moreover, distinct fluctuation of the transient heat flux of pool boiling under heaving conditions is found for all boiling regimes. Furthermore, the heaving condition shows both positive and negative effects on pool boiling heat transfer at high-gravity and low-gravity regions, respectively. Besides, both the larger heaving height and shorter period time bring out more violent heaving motion and make a greater impact on pool boiling heat transfer.

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Section: Introductionsupporting

confidence: 84%

“…Similar results could also be found in the simulation by Ma et al (2017) and experiments by Raj et al (2010). Besides, the gravity influences on CHF have also been studied in previous research studies (Raj et al, 2010;Ma et al, 2017;Fang et al, 2019), and the results showed that higher gravity within a certain range could increase CHF.…”

Section: Introductionsupporting

confidence: 84%

Numerical Investigation of Pool Boiling Under Ocean Conditions with Lattice Boltzmann Simulation. Part Ⅰ: Heaving Condition

Zou

Liu

et al. 2021

Front. Energy Res.

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“…The heat fluxes for the two larger sizes were comparable at the same wall temperature, while a non-departing primary bubble was formed on 0.81 Â 0.81 mm 2 . The recent experiments conducted by Raj [4] at 1.7 g e using three heater sizes are in consistency. Hence, it was concluded that below the particular heater size, boiling is dominated by surface tension and the nucleate boiling curve is heater-size-dependent.…”

Section: Introductionmentioning

confidence: 54%

Experimental study of the heater size effect on subcooled pool boiling heat transfer of FC-72 in microgravity

Wang

Zhao

et al. 2016

Experimental Thermal and Fluid Science

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Experiments of highly subcooled nucleate pool boiling of FC-72 with dissolved air were conducted on a large scale silicon chip (2 Â 2 Â 0.05 cm 3 , denoted as chip S 2 Â 2) in short-term microgravity condition and normal gravity condition by utilizing the drop tower in Beijing respectively. The results were compared with published results of a smaller scale chip (1 Â 1 Â 0.05 cm 3 , denoted as chip S 1 Â 1) both in normal gravity condition and microgravity condition, to study the heater size effect on boiling heat transfer. It is indicated that in microgravity, the input heat flux range in which bubble departure took place for chip S 2 Â 2 is wider than that for chip S 1 Â 1, and an interesting phenomenon observed is that coalesced bubbles departed at a continuously smaller radii at a given heat flux. Initially, the average bubble departure radii for chip S 2 Â 2 increased linearly with heat flux while later remained constant. At a same heat flux, chip S 2 Â 2 showed a bubble departure radius larger than that of chip S 1 Â 1. By comparison, it is found that nucleate boiling performance deteriorates with increase in heater size in both earth gravity condition and microgravity condition. However, in microgravity the q CHF of chip S 2 Â 2 is 20% greater than that of chip S 1 Â 1, contrary to the CHF characteristic in earth ground condition. Moreover, boiling patterns in microgravity are different in high heat flux region: a smooth hemispherical bubble was generated on chip S 1 Â 1, while on chip S 2 Â 2 an oblate vapor blanket was formed, which indicates that different dominated boiling heat transfer mechanisms exist in both cases. It is found that in microgravity, the boiling was dominated by buoyancy for chip S 2 Â 2, but it was in surface tension dominated boiling regime for chip S 1 Â 1, which proved the above speculation. Moreover, the range of transition heater size criteria is 1:45 < L h Lc < 2:89 in the present work. By using the updated model developed by Raj and Kim, it is discovered that predicted values are generally lower than experimental values in both experiments. Moreover, differences were more evident for chip S 2 Â 2.

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“…Refs. [6][7][8]. Boiling has been found to be buoyancy-dominated for heaters above a certain minimum size and to be surface-tension-dominated below this minimum heater size.…”

Section: Introductionmentioning

confidence: 99%

Pool boiling in deep and shallow vessels and the effect of surface nano-texture and self-rewetting

Sankaran

Zhang

Yarin

2018

International Journal of Heat and Mass Transfer

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Pool boiling of ethanol and self-rewetting fluids on bare copper surface and copper surface with polymer nanofibers were studied experimentally. No significant effect of the depths of ethanol layer on the heat removal rate was found. That indicates that only the heat transfer in the liquid microlayer near the heater surface is a dominant factor. As a result, one can expect that selfrewetting fluids can significantly affect boiling performance. Accordingly, several alcohol solutions including the self-rewetting ones were investigated as working fluids in the boiling chamber. It was found that at the 0.1% (v/v) concentration, only the high carbon-alcohol, nheptanol in aqueous solution, improved boiling heat transfer considerably. Furthermore, the experimental study of the effect of surface nano-texture on boiling characteristics was undertaken. For that aim, polyacrylonitrile (PAN) nanofibers were deposited onto the copper heater surface. Measurements of the boiling curve revealed a detrimental effect of such nano-texture in the case of such working fluids as ethanol and self-rewetting n-heptanol solutions. On the other hand, when polystyrene (PS) nanofibers were deposited onto the copper heater surface instead of PAN nanofibers, a significant improvement in boiling heat transfer was observed. The more hydrophobic nature of PS compared to copper is responsible for this effect, i.e. is the reason of the heat transfer enhancement on such a nano-textured surface compared to the pure copper one. In addition, the critical heat flux in the case of n-heptanol solution was found to be reduced considerably on the PS nano-textured surface compared to the pure copper one. This stems from the increased propensity of the heater surface to be covered by vapor, while the rewetting is insufficiently effective at high heat fluxes in presence of PS nanofibers.

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Gravity Scaling Parameter for Pool Boiling Heat Transfer

Cited by 28 publications

References 11 publications

Numerical Investigation of Pool Boiling Under Ocean Conditions with Lattice Boltzmann Simulation. Part Ⅰ: Heaving Condition

Numerical Investigation of Pool Boiling Under Ocean Conditions with Lattice Boltzmann Simulation. Part Ⅰ: Heaving Condition

Experimental study of the heater size effect on subcooled pool boiling heat transfer of FC-72 in microgravity

Pool boiling in deep and shallow vessels and the effect of surface nano-texture and self-rewetting

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