Effects of heater surface orientation on the critical heat flux—I. An experimental evaluation of models for subcooled pool boiling

While the role of the liquid properties, surface morphology, and operating conditions on critical heat flux (CHF) in pool boiling is well investigated, the effect of the properties of the heater material is not well understood. Previous studies indicate that the heater thickness plays an important role on the CHF phenomenon. However, beyond a certain thickness, called the asymptotic thickness, the local temperature fluctuations on the heater surface caused by the periodic bubble ebullition cycle are evened out, and the CHF is not influenced by further increasing the thickness. In the present work, data from literature and pool boiling experiments conducted in this study with seven substrates—aluminum, brass, copper, carbon steel, Monel 400, silver, and silicon—are used to determine the effect of the thermophysical property of the material on CHF for thick heaters that are used in industrial pool boiling applications. The results indicate that the product of density (ρ) and specific heat (cp) represents an important substrate property group that affects the CHF, and that the thermal conductivity is not an important parameter. A well-established force-balance-based CHF model (Kandlikar model) is modified to account for the thermal properties of the substrate. The predicted CHF values are within 15% of the experimental results.

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Influence of orientation and roughness of heater surface on critical heat flux and pool boiling heat transfer coefficient of nanofluid

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2017.06.025 ◽

2017 ◽

Vol 124 ◽

pp. 353-361 ◽

Cited By ~ 33

Author(s):

Mina Dadjoo ◽

Nasrin Etesami ◽

Mohsen Nasr Esfahany

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Critical Heat Flux ◽

Boiling Heat Transfer ◽

Pool Boiling ◽

Heater Surface ◽

Pool Boiling Heat Transfer ◽

Boiling Heat Transfer Coefficient

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The effects of surface orientation, heater size, wettability, and subcooling on the critical heat flux enhancement in pool boiling

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2019.119230 ◽

2020 ◽

Vol 149 ◽

pp. 119230 ◽

Cited By ~ 2

Author(s):

Shangzhen Xie ◽

Qing Tong ◽

Y. Guo ◽

Xuhui Li ◽

Haojie Kong ◽

...

Keyword(s):

Heat Flux ◽

Critical Heat Flux ◽

Pool Boiling ◽

Surface Orientation ◽

Flux Enhancement

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Effects of heater surface orientation on the critical heat flux—II. A model for pool and forced convection subcooled boiling

International Journal of Heat and Mass Transfer ◽

10.1016/s0017-9310(97)00077-x ◽

1997 ◽

Vol 40 (17) ◽

pp. 4021-4030 ◽

Cited By ~ 17

Author(s):

Matthew J. Brusstar ◽

Herman Merte

Keyword(s):

Heat Flux ◽

Forced Convection ◽

Critical Heat Flux ◽

Surface Orientation ◽

Heater Surface ◽

Subcooled Boiling

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Effects of Surface Orientation on the Pool Boiling Heat Transfer in Water/2-Propanol Mixtures

Journal of Heat Transfer ◽

10.1115/1.2825972 ◽

1999 ◽

Vol 121 (1) ◽

pp. 80-88 ◽

Cited By ~ 15

Author(s):

S. Ahmed ◽

V. P. Carey

Keyword(s):

Heat Transfer ◽

Surface Tension ◽

Heat Flux ◽

Binary Mixtures ◽

Critical Heat Flux ◽

Boiling Heat Transfer ◽

Pool Boiling ◽

Bulk Liquid ◽

Heater Surface ◽

Pool Boiling Heat Transfer

To explore the role of Marangoni effects in the pool boiling heat transfer of binary mixtures, experiments have been conducted with water/2-propanol mixtures at three different concentrations under normal gravity with different orientations of the heater surface. The system pressure was subatmospheric (∼5.5 kPa) and the bulk liquid temperature was near the saturation temperature of the fluids tested. The molar concentrations of2-propanol tested were 0.015, 0.025, and 0.1. These concentrations of 2-propanol are selected because their strong variation of surface tension with concentration gives rise to high surface tension gradients near the heater surface during nucleate boiling. Boiling curves were obtained both for an upward-facing and a downward-facing heater surface. For each concentration of 2-propanol, the critical heat flux has been reached in both orientations of the heater surface. Models of pool boiling heat transfer and the critical heat flux condition for binary mixtures are tested to correlate the data. Comparison of boiling curves and CHF obtained at different orientations of the heater surface indicates that there is strong gravity independent mechanism of boiling heat transfer in these mixtures.

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