The mechanism of heat transfer in nucleate pool boiling—Part I: Bubble initiaton, growth and departure
TL;DR: In this article, a criterion for bubble initiation from a gas filled cavity on a surface in contact with a superheated layer of liquid was developed, and it was found that the temperature of bubble initiation on a given surface is a function of the temperature conditions in the liquid surrounding the cavity as well as the surface properties themselves.
About: This article is published in International Journal of Heat and Mass Transfer.The article was published on 1965-06-01. It has received 457 citations till now. The article focuses on the topics: Bubble point & Maximum bubble pressure method.
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TL;DR: In this paper, a theoretical model is developed to describe the hydrodynamic behavior of the vapor-liquid interface of a bubble at the heater surface leading to the initiation of critical heat flux (CHF) condition.
Abstract: A theoretical model is developed to describe the hydrodynamic behavior of the vapor-liquid interface of a bubble at the heater surface leading to the initiation of critical heat flux (CHF) condition. The momentum flux resulting from evaporation at the bubble base is identified to be an important parameter. A model based on theoretical considerations is developed for upward-facing surfaces with orientations of 0 deg (horizontal) to 90 deg (vertical). It includes the surface-liquid interaction effects through the dynamic receding contact angle. The CHF in pool boiling for water, refrigerants and cryogenic liquids is correctly predicted by the model, and the parametric trends of CHF with dynamic receding contact angle and subcooling are also well represented
734 citations
TL;DR: In this article, a simple general relation for bubble growth rates in a uniformly superheated liquid was derived, and the relation was valid in both regions: inertia controlled and heat diffusion controlled growth, respectively.
516 citations
TL;DR: In this paper, it is shown that a thin layer of liquid (the microlayer) forms beneath the vapour bubble, which can also be deduced from a simple theory for the hydrodynamics of the formation of the layer.
439 citations
TL;DR: In this article, the authors characterized pool boiling on surfaces with wettabilities varied from superhydrophobic to super-hydrophilic, and provided nucleation measurements, and developed an analytical model that describes how biphilic surfaces effectively manage the vapor and liquid transport, delaying critical heat flux and maximizing the heat transfer coefficient.
428 citations
TL;DR: In this article, a detailed and thorough parametric study of the Leidenfrost point (LFP) is presented, which serves as the temperature boundary between the transition and film boiling regimes.
Abstract: Recent demands for superior material properties and more efficient use of materials and production time are forcing manufacturers to develop intelligent processing techniques for enhanced process control in order to better dictate the end product. In the heat treatment and processing of metallic alloys, the desire to obtain parts of enhanced and uniform mechanical properties is requiring increased control over heat removal rates and enhanced temperature control. In particular, spray quenching has been shown to be an effective means to control and enhance the cooling rates of heat treatable aluminum alloys. This study presents a detailed and thorough parametric study of the Leidenfrost point (LFP), which serves as the temperature boundary between the transition and film boiling regimes. Sessile drop evaporation experiments were conducted with acetone, benzene, FC-72, and water on heated aluminum surfaces with either polished, particle blasted, or rough sanded finishes to observe the influential effects of fluid properties, surface roughness, and surface contamination on the LFP. A weak relationship between surface energies and the LFP was observed by performing droplet evaporation experiments with water on polished copper, nickel, and silver surfaces. Additional parameters which were investigated and found to have negligible influence on the LFP included liquidmore » subcooling, liquid degassing, surface roughness on the polished level, and the presence of polishing paste residues. The accumulated LFP data of this study were used to assess several existing models which attempt to identify the mechanisms which govern the LFP. The disagreement between the experimental LFP values and those predicted by the various models suggests that an accurate and robust theoretical model which effectively captures the LFP mechanisms is currently unavailable.« less
361 citations
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01 Jan 1951
1,114 citations
TL;DR: In this paper, the equations governing spherically symmetric phase growth in an infinite medium are first formulated for the general case and then simplified to describe growth controlled by the transport of heat and matter.
832 citations
TL;DR: In this paper, the authors proposed a model to define the size range of active cavities as a function of wall temperature or heat flux, and showed that maximum and minimum sizes of effective cavities are functions of subcooling, pressure of the system, physical properties, and the thickness of the superheated liquid layer.
Abstract: The importance of surfare condition on nucleate boiling has long been recognized. It has also been known that only cavities of a narrow size range can be active nucleation sites. In order to define the size range of active cavities as a function of wall temperature or heat flux, a model is proposed. The model pictures a bubble nucleus at a site enveloped by a warm liquid. The nucleus will begin to grow into a bubble only when the surrounding liquid is sufficiently superheated. The time required for the liquid to attain this superheat is called the waiting period. The transfer of heat from the superheated liquid into the bubble is considered to be a transient conduction process. A cavity is considered effective only if the waiting period is finite. This criterion gives the limiting sizes of effective cavities. The equations show that maximum and minimum sizes of effective cavities are functions of subcooling, pressure of the system, physical properties, and the thickness of the superheated liquid layer. Comparison of theoretical prediction with experimental data from several sources was made. The fluids considered were ether, pentane, and water, with water under various degrees of subcooling. The theory did predict the incipience of boiling and size range of cavities successfully.
832 citations
01 Dec 1958
TL;DR: In this paper, a single cavity nucleation model was proposed to characterize the gross nucleation properties of a given surface for all fiuids under all conditions with a single group having the dimensions of length.
Abstract: Nucleation from a single cavity was studied indicating that cavity geometry is important in two ways. The mouth diameter determines the superheat needed to initiate boiling and its shape determines its stability once boiling has begun. Contact angle is shown to be important in babble nucleation primarily through its effect on cavity stability. Contact angle measurements made on''clean'' and paraffin coated stainless steel surfaces with water show that the contact angle varies between 20 and 110 deg for temperatures from 20 to 17O deg C. On the basis of single cavity nucleation theory, it is proposed to characterize the gross nucleation properties of a given surface for all fiuids under all conditions with a single group having the dimensions of length. Finally, it is shown experimentally that this characterization is adequate by boiling water, methanol and ethanol different copper surfaces finished with 3/0 emery, and showing that the number of active centers per unlt area is a function of this variable alone. (auth)
235 citations
216 citations