Experiments to understand bubble base growth mechanism(s) on hydrophobic surfaces under the influence of bulk flow inertia during nucleate boiling regime

Moiz, Mohd; Vadlamudi, Sai Raja Gopal; Srivastava, Atul

doi:10.1016/j.icheatmasstransfer.2022.106546

Cited by 12 publications

(2 citation statements)

References 25 publications

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“…Moiz et al [35] sought to understand the bubble base growth mechanisms on hydrophobic surfaces under the influence of bulk flow inertia and compare them to hydrophilic surfaces in similar conditions at low heat fluxes. Specifically, they investigated microlayer formation under flow boiling bubbles on a hydrophobic surface with a contact angle of 90°.…”

Section: Wettability Focused Coatingsmentioning

confidence: 99%

A Review on Flow Boiling Enhancement on Textured Surfaces

Mertens,

Castagne,

Vetrano

2024

Energies

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It is widely established that flow boiling, being a direct cooling technique also employing the latent heat of the fluid, has the potential to be more efficient than being useful in single-phase conventional cooling methods. This results in considerable potential for thermal management in many fields like microelectronics, space technology, thermal power plants, etc. The increasing demand for heat dissipation, consequent to component miniaturization, has pushed the development of new strategies for enhancing heat transfer efficiency, such as employment of functionalized surfaces. This review aims to describe in detail the current status of technology related to flow boiling heat transfer enhancement via micro/nanoscale surface functionalization. Key objectives are an increased nucleation site density and enhanced bubble dynamics. The vast majority of findings show favorable heat transfer performance, evidenced by an earlier onset of boiling (ONB), an improved flow boiling heat transfer coefficient (HTC), and an ameliorated critical heat flux (CHF). Increased pressure drop is a serious concern in certain application cases. Nanoscale textures mainly enhance capillary wicking to nucleation sites, thus being more effective in combination with microscale textures that define fixed nucleation sites. Degradation effects need to be more thoroughly and systematically characterized for application cases. Extra effects related to the manufacturing process can be easily overlooked, but one should be aware of their possible existence when drawing conclusions. Finally, the implementation of enhanced surfaces in mainstream applications is hindered by the absence of general predictive design tools for different channel configurations/materials, fluids, and operating conditions. A more universal understanding of the basic mechanisms involving texture geometry is needed in this aspect.

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Section: Wettability Focused Coatingsmentioning

confidence: 99%

A Review on Flow Boiling Enhancement on Textured Surfaces

Mertens,

Castagne,

Vetrano

2024

Energies

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“…In the last few years, such detailed studies are being carried out both in pool and flow boiling conditions [3]- [5]. In our previous works, we have reported bubble, microlayer and dry patch dynamics involved in flow boiling for single [2], [3], [6], [7] and multiple nucleations [8].…”

Section: Introductionmentioning

confidence: 99%

Ignored/Intriguing Processes Involved During Bubble Lift-Off Stage in Flow Boiling

Moiz,

Vadlamudi,

Srivastava

2024

Proceedings of the 9th World Congress on Momentum, Heat and Mass Transfer

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Traditionally the bubble departure and/or lift-off processes have been predicted based on force balance approach. However, recent experiments dedicated towards fundamentally understanding the pool and flow boiling have revealed severe limitations in the force balance approach towards accurately predict either bubble departure or bubble lift-off. In fact, the bubble lift-off process is very complex in flow boiling, involving asymmetric depletion of microlayer and rewetting of dry patch, it was poorly understood, mainly due to the limitations of measurement techniques. Our experimental measurements using state-of-the-art visible wavelength light-based imaging techniques -thin film interferometry and rainbow schlieren deflectometry-revealed many interesting and complex phenomena during the lift-off process. Among the many observations made, two phenomena highlight the complicated nature of boiling process and warrant proper discussion. First, the phenomenon of rapid ejection of bubbles in the normal direction to the heater surface (without sliding), almost perpendicular to the direction of buoyancy. Second, the appearance of bubble on the heater surface from the side-view, but with no real contact with the heater surface (as indicated by thin film interferograms). Particularly, the first phenomenon captured by thin-film interferograms revealed an intriguing pattern: an unusual depletion of microlayer from the downstream direction. To the best of our knowledge, such a phenomenon has not been reported/explored prior to this work.

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