Roughness and surface material effects on nucleate boiling heat transfer from cylindrical surfaces to refrigerants R-134a and R-123

Jabardo, José María Sáiz; Ribatski, Gherhardt; Stelute, Elvio Bugança

doi:10.1016/j.expthermflusci.2008.12.004

Cited by 72 publications

(27 citation statements)

References 24 publications

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“…Additional information regarding the experimental set-up and procedures can be found in Stelute [2], Ribatski [31], and Saiz Jabardo et al [32]. Heat transfer coefficient, minimum uncertainty ± 1.3%…”

Section: Experimental Set Upmentioning

confidence: 99%

An Overview of Surface Roughness Effects on Nucleate Boiling Heat Transfer~!2009-10-31~!2010-01-01~!2010-04-16~!

Jabardo¹

2010

TOTPJ

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Abstract:The paper aims at an overview of heating surface microstructure effects on nucleate boiling heat transfer. A comprehensive chronological literature survey is presented followed by an analysis of the results of an experimental investigation. Boiling data of refrigerants R-134a and R-123 on 19 mm diameter copper and brass tubes of average surface roughness varying from 0.07 μm to 10.5 μm have been gathered under the present investigation. Though most of the data confirm previous literature trends, according to which the heat transfer coefficient increases with surface roughness, very rough surfaces present a peculiar behavior with respect to that of the smoother surfaces (Ra<3.0 μm). Heat transfer performance of very rough surfaces is superior to the smoother ones at low heat fluxes (q<20 kW/m 2 ). However, decay in their thermal performance is observed in the high heat fluxes range. An in depth analysis of the effect of roughness on the slope, "m" of the h vs q curves has been performed with a general conclusion being that "m" is affected not only by de pressure but also by the surface roughness. Finally, an analysis of the active cavities density is performed using some models from the literature in order to evaluate the effect of surface roughness in cavity activation. The obtained results are generally inconclusive. However, it has been determined that surface microstructure effects must not be neglected in future models.

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Section: Experimental Set Upmentioning

confidence: 99%

An Overview of Surface Roughness Effects on Nucleate Boiling Heat Transfer~!2009-10-31~!2010-01-01~!2010-04-16~!

Jabardo¹

2010

TOTPJ

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“…As aforementioned and despite the big advances in recent years, no strong theoretical and global mechanistic model has been developed yet [5,6]. As noted by several authors [5,8] due to the vague knowledge of bubble formation at macro and microstructure levels, many of the past and recent predictive methods in practice are based on empirical and semi-empirical models.…”

Section: Introductionmentioning

confidence: 99%

“…In this context, heat transfer employing boiling mechanisms is a proper option to take into account. Nevertheless, despite being analysed in depth since the first half of the 20th century, nucleate boiling phenomenon is still unresolved at a global scale and no coherent theory has been established [1][2][3][4][5][6] mainly due to the great complexity of mass and energy transport mechanisms related with the two phases and the wide range of factors involved. This complexity is explained by the variety of characteristic length and time scales that take part in the process of bubble nucleation, growth, detachment, coalescence and collapse.…”

Section: Introductionmentioning

confidence: 99%

On the effect of surface roughness and material on the subcooled flow boiling of water: Experimental study and global correlation

Paz

Conde

Suárez

et al. 2015

Experimental Thermal and Fluid Science

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.On the effect of surface roughness and material on the subcooled flow boiling of water: Experimental study and global correlation. AbstractIn this paper, a new correlation based on experimental results for subcooled flow boiling of water at low pressure is proposed, preceded by a brief review on how the solid-fluid interaction has been dealt with in past correlations. The experimental sample comprises seven heating surfaces of different material (copper, aluminium and stainless steel) and roughness. The experimental facility is presented in detail and the surface morphology of each test specimen is analysed by means of an optical interferometer. The correlation is based on the assumption that the effect of material and roughness can be captured by means of modifiers of a general expression. The surfaces chosen in this work were selected to capture a broad range of industrial applications, and, though the correlation found fits well in the range of commercial and relatively high values of R a (up to 7 µm in the case of copper), further study is needed for larger values, as a discontinuity in the effect was observed, which has been previously determined by some authors. Thus, the proposed global correlation permits the calculation of the boiling heat flux taking into account, in addition to the more classical parameters such as pressure and bulk temperature, the effect of both the roughness and material of the wall heater, allowing its general use in low pressure applications such as those commonly found in the automotive industry.

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“…58 µm for v=5 m/min. Based on a review of selected literature presented in the bibliography concerned with the issues of heat transfer intensification involving the working medium phase, the highest values (R a ) of sample surfaces used for tests were recorded as follows: 10 µm in [10], 10.5 µm in [12], 13.04 µm in [9] or 13.33 µm in [11]. As a consequence of applying vibration-laser treatment, the R a values are significantly higher and should have a significant impact on the improvement of heat dissipation properties.…”

Section: Profilometric Evaluationmentioning

confidence: 99%

“…The techniques are used to modify the metal surface by means of, among others, the following types of reaction: a) chemical -pits obtained through chemical reactions, [3], [8], b) thermal -sintering of metal particles, [4], c) mechanical -creating microribs on the surface, application of finely cut grooves, making valleys, holes, projections or sand blasting, shot-peening, treatment with abrasive paper or abrasive compounds [7], [8], [9], [11], [12], d) laser beam -(making microholes by means of a laser beam, laser melting) and electrical discharge machining (EDM) [5], [6], [10]. The presented paper discusses the preliminary results of experimental research on the new technology of enhancing the roughness of metal elements.…”

Section: Introductionmentioning

confidence: 99%

An Evaluation of the use of Laser-Vibration Melting to Increase the Surface Roughness of Metal Objects

Grabas¹

2015

Archives of Metallurgy and Materials

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This paper presents preliminary, experimental results of a new, hybrid method of increasing the surface roughness of metal objects. In this new approach, metal objects are melted with a mobile laser beam while they are being rotated. A vibration generator provides circular vibrations with an amplitude of 3 mm, and the vibration plane is perpendicular to the moving laser beam. The melting tests were performed using flat carbon steel samples at a predetermined frequency of circular vibrations. The effects of laser power and laser beam scanning velocity on the melted shapes were studied. All laser melting procedures were performed at a vibration frequency of 105 Hz. The melted samples were subjected to microscopic evaluation and the R a parameter, which characterises mean roughness, was measured using a profilometer. Melting metal samples with physically smooth surfaces (R a = 0.21 µm) resulted in surface structures of varied roughness values, with R a ranging from 5 µm to approximately 58 µm. The studies were undertaken to employ this technology for the purpose of passive heat exchange intensification of heating surfaces in practical applications.Keywords: laser melting, surface roughness, laser treatment, vibration, nucleate boiling W artykule zaprezentowano wstępne wyniki eksperymentalne nowej hybrydowej metody zwiększania chropowatości powierzchni elementów metalowych. W metodzie tej wykorzystuje się przetapianie ruchomą wiązką laserową elementów metalowych poddanych równocześnie wibracji kołowej. Generator drgań wytwarza wibrację kołową o amplitudzie 3 mm, a płaszczyzna wibracji jest prostopadła do osi przemieszczającej się wiązki laserowej. Próbom przetapiania przy ustalonej częstotliwości wibracji kołowej poddano płaskie próbki ze stali węglowej. Badano wpływ mocy laserowej oraz prędkości skanowania wiązki laserowej na kształt przetopień. Wszystkie przetopienia laserowe wykonywano przy częstotliwości wibracji f = 105 Hz. Otrzymane przetopy poddane zostały obserwacjom mikroskopowym oraz pomiarom profilometrycznym parametru R a charakteryzującego średnią chropowatość. W wyniku przetapiania technicznie gładkich powierzchni próbek metalowych (R a = 0,21 µm), uzyskano struktury o zróżnicowanych chropowatościach, dla których R a mieścił się w przedziale od ok. 5 µm do ok. 58 µm. Badania prowadzono pod kątem potencjalnych możliwości stosowania tej technologii do pasywnej intensyfikacji wymiany ciepła powierzchni płyt grzewczych.

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Roughness and surface material effects on nucleate boiling heat transfer from cylindrical surfaces to refrigerants R-134a and R-123

Cited by 72 publications

References 24 publications

An Overview of Surface Roughness Effects on Nucleate Boiling Heat Transfer~!2009-10-31~!2010-01-01~!2010-04-16~!

An Overview of Surface Roughness Effects on Nucleate Boiling Heat Transfer~!2009-10-31~!2010-01-01~!2010-04-16~!

On the effect of surface roughness and material on the subcooled flow boiling of water: Experimental study and global correlation

An Evaluation of the use of Laser-Vibration Melting to Increase the Surface Roughness of Metal Objects

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