Post-critical heat flux heat transfer: A survey of current correlations and their applicability

Wang, S.W.; Weisman, J.

doi:10.1016/0149-1970(83)90021-5

Cited by 9 publications

(4 citation statements)

References 28 publications

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“…The attainment of the critical heat flux (chf) is followed, in turn, by a brief transition boiling region where heat flux decreases as DT sat increases. When DT sat is sufficiently high to prevent liquid contact, the surface is completely covered by a vapour film and film boiling occurs [34]. Figure 4 illustrates the pool boiling curve as first measured by Nukiyama showing the different boiling regimes and important salient values.…”

Section: Boiling Curvesmentioning

confidence: 95%

“…Transition or partial film boiling is an unstable mode of heat transfer in which both nucleate and film boiling coexist (or alternate) at the same location, so that a liquid film is present only part of the time. Intermittent wetting produces significant wall temperature oscillations as these two different boiling mechanisms compete [34,36], causing the size of the wetted region to expand and contract periodically [36]. It is usually suggested that the transition boiling heat fluxes can generally be estimated by drawing a straight line on a semi-log plot of heat flux versus DT sat (heat flux on the log scale).…”

Section: Boiling Curvesmentioning

confidence: 99%

“…However, the procedure ignores the complications due to the surface wetting direction of approach to the transition boiling region, and the effect of subcooling as discussed by Witte and Lienhard [43]. It does, nevertheless, provide a reasonable heat flux result for saturated liquid, on a moderately clean surface in the absence of surface active agents [34]. The direction of approach referred to above relates to whether cooling or heating is studied.…”

Section: Boiling Curvesmentioning

confidence: 99%

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Analysis of residual strain and stress states due to heat treatment and thermal processing

Vorster

Korsunsky

2008

The Journal of Strain Analysis for Engineering Design

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This paper dwells on the nature of the highly non-linear interactions occurring during heat treatments with the aim of developing an improved understanding of the process and of the residual strains and stresses formed in heat-treated components during processing. As an example, two industrial quench processes are analysed. A general analytical strategy is presented to study not only these processes, but is formulated in such a way that it may also be extended to other thermomechanical processes. This strategy may therefore serve as a roadmap for industrial designers to analyse thermomechanical processes for optimization. Results in the broad framework of thermomechanical processing indicate that careful characterization and correct representation of the heat transfer conditions leads to significant improvements in accuracy over the current quench modelling techniques. In addition to this, the nature of the thermomechanics involved in spray and bath quench processes is analysed. Neutron diffraction experiments and finite element analyses indicate that the use of water sprays reduces the depth of permanent deformation in quenched components compared to those treated in a water bath. It is shown that this is a direct consequence of the rewetting condition. Understanding the processes involved enables the processing engineer to perform optimization studies of the thermomechanical process, before processing. This ultimately allows production of engineering components with superior mechanical properties, reduced distortion and well-controlled beneficial residual stress states.

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Section: Boiling Curvesmentioning

confidence: 95%

Section: Boiling Curvesmentioning

confidence: 99%

Section: Boiling Curvesmentioning

confidence: 99%

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Analysis of residual strain and stress states due to heat treatment and thermal processing

Vorster

Korsunsky

2008

The Journal of Strain Analysis for Engineering Design

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“…This could result in local dry out which could have an effect on the oscillatory motion of the quench front, often observed during transition boiling studies [19,20].…”

Section: High Speed Imaging Of Spray Fieldmentioning

confidence: 99%

Analysis of the spray field development on a vertical surface during water spray-quenching using a flat spray nozzle

Vorster

Schwindt

Schupp

et al. 2009

Applied Thermal Engineering

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.Analysis of the spray field development on a vertical surface during water spray-quenching using a flat spray nozzle Abstract -The aims of this study were (i) to conduct experimental spatially and time-resolved measurements of flow development on large heated surfaces during transient spray cooling operations, and (ii) to investigate and discuss the influence of spray cooling mechanisms such as bubble formation and the flow field development of the cooling fluid and how this affects heat transfer. Quartz plates were heated to above 500°Cand then sprayed with pressurised water subcooled to 80K. High speed images of the quench process were collected at a rate of 3000 Hz making it possible to track the movement of the quench front as the plate cools below the Leidenfrost temperature of the fluid at that location. Observations showed that the relative importance of droplet-surface interactions decreases once the Leidenfrost temperature is reached on the plate:It was found that once the water contacts the surface, a water pool develops rapidly which grows larger as the pool floods the heated surface. Comparisons between the spatial flow development and heat transfer on the plate are made in order to describe these interactions more accurately. This information not only provides crucial input into process simulations, but is also useful to develop theoretical models of fluid-solid interaction describing the wetting of a heated component due to water spraying.

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Critical Heat Flux, Post-CHF Heat Transfer and Their Augmentation

Celata¹,

Mariani²

2003

Modelling and Experimentation in Two-Phase Flow

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Post-critical heat flux heat transfer: A survey of current correlations and their applicability

Cited by 9 publications

References 28 publications

Analysis of residual strain and stress states due to heat treatment and thermal processing

Analysis of residual strain and stress states due to heat treatment and thermal processing

Analysis of the spray field development on a vertical surface during water spray-quenching using a flat spray nozzle

Critical Heat Flux, Post-CHF Heat Transfer and Their Augmentation

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