A study of local heat transfer mechanisms along the entire boiling curve by means of microsensors

Buchholz, Martin; Auracher, Hein; Lüttich, Torsten; Marquardt, Wolfgang

doi:10.1016/j.ijthermalsci.2004.08.007

Cited by 37 publications

(31 citation statements)

References 16 publications

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“…The corresponding measurements obtained by micro optical probes [35] yield information about vapor-liquid structures and for some extent interface velocities of the two-phase structure above the surface. In combination with the associated heat flux distribution and dynamics evaluated in the present work, a data basis is available for the development of realistic mechanistic heat transfer models for boiling regimes beyond low heat flux nucleate boiling, where heat transfer models can be based on the study of single undisturbed bubbles.…”

Section: Discussionmentioning

confidence: 99%

“…Using a temperature controlled heater, boiling curves for some test fluids have been evaluated [12,35]. In this section, we use the obtained temperature measurement inside the heater to estimate the local heat flux q b at the fluid/heater interface C B .…”

Section: Estimation With Measurement Data From Pool Boiling Experimentsmentioning

confidence: 99%

“…The characteristics of temperature fluctuations in the different boiling regimes are associated with the dynamics of the two-phase layer above the heater surface. This has been measured with the same test heater by micro optical probes at different heights above the heater [35]. These measurements yield information about vapor-liquid structures and for some extent interface velocities of the two-phase structure above the surface.…”

Section: Estimation With Measurement Data From Pool Boiling Experimentsmentioning

confidence: 99%

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Reconstruction of local heat fluxes in pool boiling experiments along the entire boiling curve from high resolution transient temperature measurements

Heng

Mhamdi

Groß

et al. 2008

International Journal of Heat and Mass Transfer

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Section: Discussionmentioning

confidence: 99%

Section: Estimation With Measurement Data From Pool Boiling Experimentsmentioning

confidence: 99%

Section: Estimation With Measurement Data From Pool Boiling Experimentsmentioning

confidence: 99%

See 1 more Smart Citation

Reconstruction of local heat fluxes in pool boiling experiments along the entire boiling curve from high resolution transient temperature measurements

Heng

Mhamdi

Groß

et al. 2008

International Journal of Heat and Mass Transfer

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“…Boiling heat transfer curves which correlate the wall-to-fluid heat flux to the wall superheat are traditionally used to explain different boiling heat transfer regimes 41 . They also facilitate predictions of overall HTC, critical heat flux (CHF), and limits for device burnout [42][43][44] . Internal two-phase flows inside microchannels also highlight the importance of different boiling regimes, depending on the heat flux, relative size of bubbles (compared to the channel dimensions), mass flux, and the vapor quality of the flow.…”

Section: Tdtr Experiments For Subcooled Boiling In Microchannelsmentioning

confidence: 99%

Transient and local two-phase heat transport at macro-scales to nano-scales

Mehrvand

Putnam

2018

Commun Phys

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Two-phase cooling has become a promising method for improving the sustainability and efficiency of high energy-density and power-density devices. Fundamentally, however, two-phase thermal transport is not well understood for local, transient processes, especially at critical to near-critical heat fluxes at the macro, micro, and nano-scales. Here we report spatiotemporal characterization of the single-bubble ebullition cycle in a hot-spot heating configuration with heat fluxes approaching 3 kW cm −2 . In particular, we experimentally reconstruct the spatiotemporal heat transfer coefficient in terms of its proportionality at both the macro-scale (l >> 1 μm) and the micro-to-nanoscale (l < 1 μm). We show that the maximum rates of heat transfer occur during the microlayer evaporation stage of the ebullition cycle, corresponding to critical maxima in the heat transfer coefficient of~160 ± 40 kW m −2 K −1 and~5300 ± 300 kW m −2 K −1 at the macro-scale and micro-to-nanoscale, respectively.

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“…It is believed that the behavior of the near-wall liquid layer plays a key role in the heat transfer and boiling crisis. To date, most of the published modeling and numerical studies on boiling heat transfer have concentrated on the near-wall liquid layers (i.e., micro-and macrolayers) with the thickness estimated to range from several to hundreds of micrometers in pool boiling (Rajvanshi et al, 1992;Kumada and Sakashita, 1995;Auracher and Marquardt, 2004;Bang et al, 2005;Buchholz et al, 2006;Ono and Sakashita, 2007). Stephan and Kern (2004) phenomena.…”

Section: Introductionmentioning

confidence: 99%

Thin Liquid Film Dynamics and Bubble Behavior in Flow Boiling

Wang

Lin

et al. 2016

Interfac Phenom Heat Transfer

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A profound knowledge of the dynamics of a thin liquid film and bubble behavior in flow boiling is crucial in a thorough study of the physical mechanisms of boiling crisis, which is important to the performance and safety of light water reactors. To address this, in the present study a series of tests were carried out at various water and air flow rates under atmospheric pressure and different heat fluxes in a horizontal copper channel. We employed a developed confocal optical sensor system to detect the variations and integrity of the thin liquid film. Additionally, we used a high-speed camera to capture the bubble behavior in detail and analyzed the effect of the film thickness on bubble behavior. According to our observations, the thinning process of the liquid film is governed by the entrainment under adiabatic or lower heat flux conditions, whereas evaporation becomes more pronounced in a higher heat flux system. The critical film thickness of an integral film is found to be related to the condition of the heating surface and the heat flux. Remarkably, the coalescence of bubbles seldom occurs in flow boiling with the thinner liquid film. The bubble departure diameter increases with an increase in the heat flux and liquid mass flow rate, but decreases with an increase in the gas flow rate. The minimum bubble departure diameter observed using high-speed photography was about 90 µm.

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A study of local heat transfer mechanisms along the entire boiling curve by means of microsensors

Cited by 37 publications

References 16 publications

Reconstruction of local heat fluxes in pool boiling experiments along the entire boiling curve from high resolution transient temperature measurements

Reconstruction of local heat fluxes in pool boiling experiments along the entire boiling curve from high resolution transient temperature measurements

Transient and local two-phase heat transport at macro-scales to nano-scales

Thin Liquid Film Dynamics and Bubble Behavior in Flow Boiling

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