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Thursday, July 30, 2020 | History

2 edition of Surface roughness effects on nucleate boiling heat transfer rates found in the catalog.

Surface roughness effects on nucleate boiling heat transfer rates

by James C. Gibson

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Published .
Written in English

    Subjects:
  • Mechanical engineering

  • The Physical Object
    Paginationp. ;
    ID Numbers
    Open LibraryOL25167549M

    @article{osti_, title = {Surface roughness and its effects on the heat transfer mechanism in spray cooling}, author = {Pais, M R and Chow, L C and Mahefkey, E T}, abstractNote = {In the spray cooling of a heated surface, variations in the surface texture influence the flow field, altering the maximum liquid film thickness, the bubble diameter, vapor entrapment, bubble departure. Nishikawa, K, Fujita, Y, Ohta, H & Hidaka, S , EFFECT OF THE SURFACE ROUGHNESS ON THE NUCLEATE BOILING HEAT TRANSFER OVER THE WIDE RANGE OF PRESSURE. in Heat Transfer, Proceedings of the International Heat Transfer Conference.

    Kandlikar S. G. Controlling bubble motion over heated surface through evaporation momentum force to enhance pool boiling heat transfer. Applied Physics Letters , – (). Kim J. Review of nucleate pool boiling bubble heat transfer mechanisms. International Journal of Multiphase F – (). the quantitative effect of the heat-transfer surface in the nucleate­ boiling region. Corty and Foust (6) observed that the size and shape distribution of the micro-roughness of the heat-transfer surface have a crucial influence on bubble formation during nucleate boiling. This micro-roughness of the boiling surface is one of the fundamental.

    It was observed that the helix-finned surface had higher bubble departure frequencies compared to plain surfaces and an earlier onset of nucleate boiling was noticed. It is concluded that the surface roughness and micron level cavities produced by the 3D printing technique on the helix surface are key factors to enhance boiling heat transfer. The experiment was conducted in order to test how surface roughness affects the rate temperature rises in aluminum. Rationale The effects of surface texture on heat transfer are not yet known. The reason for this experiment is to provide initial observations on the effects that increasing surface textures have on the amount of heat transferred.


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Surface roughness effects on nucleate boiling heat transfer rates by James C. Gibson Download PDF EPUB FB2

The effect of surface roughness on pool boiling heat transfer is experimentally explored over a wide range of roughness values in water and Fluorinert ™ FC, two fluids with different thermal properties and wetting characteristics. The test surfaces ranged from a polished surface (⁠ R a between μ m and μ m ⁠) to electrical discharge machined (EDM) surfaces with a Cited by: The Influence of Surface Roughness on Nucleate Pool Boiling Heat Transfer The effect of surface roughness on pool boiling heat transfer is experimentally explored over a wide range of roughness values in water and Fluorinert™ FC, two fluids with different thermal properties and wetting characteristics.

The test surfaces ranged from a. The effect of surface roughness on the nucleate boiling heat transfer and CHF at copper surfaces having moderate contact angles in pool boiling of saturated water was investigated.

The average roughness R a was varied from μm to μm, and static and dynamic contact angles were measured before and after each boiling test for all nine Cited by: The influence of surface roughness on nucleate boiling heat transfer was investigated by [12] [13][14][15][16]. The major conclusion from these studies indicates that increases in the surface.

The heat flux increased as the surface roughness increased in the pure water, but the effect of surface roughness on heat flux was unclear in the nanofluid. This was attributable to the decreased difference of surface roughness, which was caused by the coating or deposition of nanoparticles on the heat transfer surface during the by: 8.

Wuu-Tsann Wu, Yu-Min Yang, Jer-Ru Maa, Enhancement of Nucleate Boiling Heat Transfer and Depression of Surface Tension by Surfactant Additives, Journal of Heat Transfer, /,2, (), ().

It has been well understood that the surface properties, e.g., surface roughness, porosity, and wettability, play a significant role in boiling heat transfer.

Among the various surface properties, surface wettability has clear, yet complicated effects on boiling heat transfer from the thermodynamic point of view. The formation of steam bubbles along a heat transfer surface has a significant effect on the overall heat transfer rate.

Boiling. in which steam completely blankets the heat transfer surface. Departure from Nucleate Boiling and Critical Heat Flux. In practice, depending on what source "book" the student has used to obtain the.

Heat transfer measurements for liquid flow rates between 1 to 5 l/h and air flow rates between to l/s are presented. Maximum heat fluxes of W/cm 2 for the μm surface. An Overview of Surface Roughness Effects on Nucleate Boiling Heat Transfer The Open Transport Phenomena Journal,Volume 2 25 roughness of the heating surface varied in the range between μm and μm whereas the measured contact angle varied from 45° to 60°.

The Corty and Foust results indicate. FIGURE TITLE PAGErectangularspecimen#in) 31rectangularspecimen#in) 32 25rectangularspecimen#3(96^>in) 33 mrectangularspecimen#4(46^in) 34 27rectangularspecimen#5(32^in) 35 28 PlotofHeatRatevs.

This paper presents results of an experimental investigation carried out to determine the effects of surface material on nucleate pool boiling heat transfer of refrigerant R Experiments were performed on horizontal circular plates of brass, copper and aluminum.

The heat transfer coefficient was evaluated by measuring wall superheat and effective heat flux removed by boiling. The objective of the study is to observe the effect of surface roughness on heat transfer. The same principal applied in current transfer when two metallic conductive materials are in amount of current passed depends upon the amount of area in contact with each other of two surfaces [6].

Effect of Surface Roughness on Heat Transfer. The effect of surface roughness on nucleate boiling heat transfer is not clearly understood. This study is devised to conduct detailed heat transfer and bubble measurements during boiling on a heater surface with controlled roughness.

This second of two companion papers presents an analysis of heat transfer and bubble ebullition in nucleate boiling with new measures of surface roughness: area. SURFACE ROUGHNESS EFFECTS ON NUCLEATE BOILING HEAT TRANSFER RATES by James C.

Gibson, Jr If Lieutenant, United States Navy Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN MECHANICAL ENGINEERING United States Naval Postgraduate School Monterey, California 1 9 6 2. Aluminium substrates of different initial roughness were used to study the roughness effect on the wettability after boiling in various nanofluid concentrations, boiling durations and heat fluxes.

heating surface will also enhance heat transfer in nucleate boiling. • Irregularities on the heating surface, including roughness and dirt, serve as additional nucleation sites during boiling. • The effect of surface roughness is observed to decay with time. Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy between physical transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase ers also consider the transfer of mass of differing chemical species.

One promising way to enhance the heat transfer coefficient (HTC) and the critical heat flux (CHF) is modifying the heating surface morphology by using machining techniques, coating, and chemical processes. Microstructured surfaces, i.e., surfaces with the presence of micropillars on the surface, provide small perturbations in the liquid, affecting the vapor bubbles dynamic.

External heat is applied and data for the forced convective, nucleate boiling and transition or critical heat flux (CHF) regimes has been obtained. The results highlighted in this paper attempt to quantify the effects of cooling passage surface roughness on the nucleate boiling regime.

modifying surface roughness and wettability or by tuning the liquid’s properties. In order to investigate the effects of surface roughness, Berenson et al.

[4] studied pool boiling of n-pentane at atmospheric pressure. The result showed an increment of times in the nucleate boiling heat transfer coefficient using roughened surfaces.constant, ε = surface roughness (µm) ()() 10 Treated similar to nucleate pool boiling heat transfer, accounting for the interaction with flow Flow Increasing vapour mass fraction nucleate boiling • Effect of flow on nucleate boiling TF 1 10 6 Re 1 +.Bradley D.

Bock, Josua P. Meyer, John R. Thome, Falling film boiling and pool boiling on plain circular tubes: Influence of surface roughness, surface material and saturation temperature on heat transfer and dryout, Experimental Thermal and Fluid Science.