Developed Boiling Heat Transfer - Forty Years of the Model of "The Theatre of Director"

2008

TOMEJ

A review discusses current status of boiling heat transfer research. Basic experimental facts, physical models and correlations of experimental data on heat transfer coefficient (HTC) are reconsidered. Principal restrictions of traditional model of "the theatre of actors" (MTA) are demonstrated. Basic role of control of HTC by thermodynamic conditions on nucleation sites is demonstrated and consequent model of "the theatre of director" (MTD) is discussed. Universal MTD-based correlation of boiling HTC of all types of liquids is presented. Unified consistent research framework for developed boiling heat transfer and diverse specific boiling heat transfer regimes is outlined through supplementing MTD by so-called multifactoring concept (MFC). MFC links transition from developed boiling mode to diverse boiling curves to a phenomenon of multiplication of factors influencing HTC. Multifactoring phenomenon equally can cover any boiling process including boiling in minichannels and microchannels. Possible types of multifactoring are considered. Finally, the ways of further research of the boiling problem are discussed.

Section: Principal Restrictions Of Mtamentioning

confidence: 99%

Section: Mtd and Mtd-based Analysismentioning

confidence: 99%

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Boiling Heat Transfer: Mechanisms, Models, Correlations and the Lines of Further Research

2008

TOMEJ

“…According to the multi-factoring concept (MFC) [41], any failure to meet these conditions results in essential transformation of heat transfer regularities up to drastic increase of the number of influencing HTC factors. For instance, depending on concrete conditions, the circle of influencing HTC factors may be widened by the parameters of inter-phase hydrodynamics, intensity of body force, contact angle, subcooling, sizes, form, orientation, and thermal characteristics of the heating surface, micro-geometry, and distribution of nucleation sites, and prehistory of the process.…”

Section: The Er Correlation Of Experimental Data and Heat Transfer mentioning

confidence: 99%

Boiling Heat Transfer: Convection Controlled by Nucleation

Heat Transfer - Models, Methods and Applications

2018

Due to the peculiar way of evolution of boiling heat transfer research, a model "theater of director" (MTD), pumping effect of growing bubble (PEGB) and MTD-based universal correlation (UC) remain beyond the attention of researchers for more than half a century.In parallel, there are periodic fundamental events, demonstrating the irrationality of such indifference. Since the 1980s, not having found a way to enhance boiling heat transfer, other than that uncovered by the MTD-UC, high-performance boiling surfaces are being developed by artificially increasing effective radius (ER) of nucleation centers (bypassing the reference to the relevant theoretical basis). In 2009, an independent review declares transient conduction and microconvection as the dominant boiling heat transfer mechanism, not knowing that this is just the PEGB. In 2014-2017, the real versatility and accuracy of the UC is confirmed by independent studies, which involve extensive databases on the pool and flow boiling (with some interpretation problems). Assessing the current status of the study, the chapter emphasizes the complete fiasco of traditionally adopted approaches, models and theories, led to the dominance of purely empirical relationships written in a dimensionless form. Heat transfer research community is invited to gain will and rid of the heavy burden of the past.

“…In order to analyze the diversity of boiling heat transfer curves different from the basic developed boiling curve, including boiling hysteresis, the MTD is supplemented by so-called MFC (Multi-factoring concept) [12]. At the same time, despite the obvious fundamental importance, the MTD-UC, the PEGB and others were subjected to general neglect during half a century.…”

mentioning

confidence: 99%

Tabooed Universal Characteristic Length and Misled Boiling Heat Transfer Research

2015

JPSA

Abstract:The paper presents the next step within multiyear fruitless efforts of the author to overcome the absurd situation in boiling heat transfer research. The focus is made on the problem of the characteristic length of the process most clearly exhibiting the consequences of half a century ignoring the basic MTD (Model "theater of director"), the UC (Universal correlation) and some other boiling fundamentals. Echoing control of boiling heat transfer by nucleation, the MTD-UC identifies universal characteristic length, the AER (Average effective radius) of nucleation sites, equally workable at the macro-and microscale. Inefficiency of the generally accepted, so called MTA (theater of actors) is particularly pronounced just in the confusion with the characteristic length. Traditional and potential candidates, departure diameter of vapor bubble and transverse internal size of the channel hardly can be adjusted to independence of developed boiling HTC on mass acceleration, subcooling, liquid convection and the heating surface geometry. At the same time, even such a problem has not prevented many authors to develop tens or even hundreds of helpless MTA-based correlations. The ignoring the MTD-UC-AER has also led to the incompleteness of the standard boiling heat transfer experiment, which is usually done without studying nucleation sites (there are available only very few comprehensive experimental works including the data on the AER). The only exception was made for the problem of boiling heat transfer enhancement: over the past decades enhanced boiling surfaces were developed in direct accordance with the principle defined by the MTD-UC (just through the AER). Another thing is that the basic role of the MTD-UC-AER in substantial progress of the relevant R&D activities passed over in silence in the corresponding publications. Enviable unity and coherence of heat transfer community in preventing real scientific debate on the problem is also remarked.