Flow boiling of R245fa in 1.1 mm diameter stainless steel, brass and copper tubes

Pike-Wilson, Emily; Karayiannis, Tassos G.

doi:10.1016/j.expthermflusci.2014.02.024

Cited by 45 publications

(8 citation statements)

References 34 publications

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“…Author also used homogeneous and separated flow models to predict the pressure drop data in the study and reported that the both models have an agreeable performance with the data. Pike-Wilson and Karayiannis [139] used copper, brass and stainless steel minichannel tubes for investigation of surface profile on the boiling and pressure drop of R245fa. A broad explanation on definition of surface roughness and different aspects of the tube materials' surface profiles were presented by authors.…”

Section: Surface Modification In Minichannels and Microchannelmentioning

confidence: 99%

A Review of Flow Boiling in Mini and Microchannel for Enhanced Geometries

Dalkılıç¹

2018

Journal of Thermal Engineering

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Flow boiling researches in enhanced geometries practiced recently have been summarized in this review. Classical approximations in macroscale flows have not applied to the flows with small hydraulic diameters, so, this subject has been paid attention by the researchers. Application areas of these structures are increasing continuously due to cooling need in small confined spaces. The related studies have been reviewed in a chronological manner and their parameters have been given in a table in order for the researchers to observe the scientific duration regarding the progresses on this subject. Almost all papers on this subject have been produced after 2000, therefore, this subject is considered as an actual one to improve and worth to study in the literature. This study can not only be evaluated as the beginning argument for the researchers involved in flow boiling process in mini and microchannel, but it also consists of new works on the investigated subject.

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Section: Surface Modification In Minichannels and Microchannelmentioning

confidence: 99%

A Review of Flow Boiling in Mini and Microchannel for Enhanced Geometries

Dalkılıç¹

2018

Journal of Thermal Engineering

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“…The effect of substrate material in flow boiling cannot be concluded from the literature due to the difference in operating conditions (mass flux, heat flux, and inlet conditions), type of fluid, diameter and heated length. To avoid the variations in the above parameters, the current research group tested flow boiling in cold drawn copper, brass and stainless steel tubes with 1.1 mm diameter and 300 mm length using R245fa, see Pike-Wilson and Karayiannis [78]. They conducted the tests in the mass flux range 100 -400 kg/m 2 s, heat flux range 10 -60 kW/m 2 , vapour quality up to 0.95 and 1.8 bar inlet pressure.…”

Section: Effect Of Boiling Surface Materialsmentioning

confidence: 99%

Flow Boiling in Micro-Passages: Developments in Fundamental Aspects and Applications

Karayiannis

Mahmoud

2018

International Heat Transfer Conference 16

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Flow boiling in mini to micro passages located at the heat source, and as part of a thermal management system, has been identified as a possible way to remove the increasing high heat fluxes generated by high power electronic devices due to their capability of high heat transfer rates with small surface temperature variations. However, some still unresolved fundamental issues hinder the possible full adoption of this technology. These relate to the prevailing flow patterns, heat transfer rates and pressure drop in such geometries, and their dependence on key parameters. The possible major applications of flow boiling in microchannels are first mentioned in this paper, highlighting the requirements and the challenges of the thermal management of each application. The paper then presents new experimental research by the present authors as well as research reported in the literature on flow boiling in single tubes and rectangular multi microchannels to help elucidate the following fundamental issues: the definition of a microchannel, prevailing flow patterns, heat transfer mechanisms, flow instability and reversal and their effect on heat transfer rates, effect of channel material and surface characteristics (including latest research in coatings), effect of different fluid properties, and its relation to channel material, effect of channel length and aspect ratio. An appreciation of the above can help explain the interpretation of the prevailing fluid flow and heat transfer phenomena and the data scatter and discrepancies observed in past studies. In addition, models and correlations predicting flow patterns and heat transfer rates are presented.

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“…First, these channels are smoother than metallic channels used in industrial heat transfer applications. Fiorenza et al [2] measured the statistical average roughness of surfaces in a polyimide heat sink using Atomic Force Microscopy (AFM), obtaining values ranging from 12 to 35 nm, while smooth metallic channels are rougher, with values on the order of 100-1000 nm [3] [4]. Wall roughness has been often reported to have an effect on the heat transfer coefficient.…”

Section: Introductionmentioning

confidence: 99%

Experimental flow boiling heat transfer in a small polyimide channel

Marzoa

Ribatski

Thome

2016

Applied Thermal Engineering

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New experimental flow boiling heat transfer results averaged along a very low thermal conductivity polyimide channel are presented. The experimental setup consists of a horizontal, 300 mm-long, 2.689 mm inner diameter polyimide tube, heated by a counter-current, external water flow. R245fa is the working fluid, at mass fluxes ranging from 100 to 500 kg m-2 s-1 , heat fluxes from 15 to 55 kW m-2 , and three saturation temperatures: 35, 41 and 47°C. Heat transfer coefficient results are presented averaged over the whole polyimide channel for mean vapor qualities ranging from 0.05 to 0.8. High-speed flow visualization was possible downstream of the polyimide tube. Parametric analysis of the results revealed a strong dependence of the heat transfer coefficients on mass flux and vapor quality, and mild influence of the heat flux and the saturation temperature. The experimental database is compared with results obtained for metallic tubes of comparable size in similar experimental facilities. Last, experimental results are contrasted with several heat transfer methods, of which a convective model for annular flow well predicts the heat transfer coefficient values and convective boiling trends.

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Flow boiling of R245fa in 1.1 mm diameter stainless steel, brass and copper tubes

Cited by 45 publications

References 34 publications

A Review of Flow Boiling in Mini and Microchannel for Enhanced Geometries

A Review of Flow Boiling in Mini and Microchannel for Enhanced Geometries

Flow Boiling in Micro-Passages: Developments in Fundamental Aspects and Applications

Experimental flow boiling heat transfer in a small polyimide channel

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