Heat transfer coefficient and cross-sectional flow structure in condensation of steam in an inclined tube at a low mass flux

The heat transfer characteristics during flow boiling of deionized water in parallel microchannels are investigated. The silicon heat sinks contain an array of integrated heaters and diodes for localized heat-flux control and temperature measurement. The channel widths for the three different test pieces range from 250 μm to 2200 μm, with a nominal depth for all channels of 400 μm. The present study investigates the effects of the channel width and mass flux on the boiling performance. This study follows a previous study using a wetting dielectric liquid, and aims to understand the role of wetting since water is relatively non-wetting. From the results of the present study, a weak dependence of the boiling curve and heat transfer coefficient on mass flux was observed. Varying the channel width also does not have a strong effect on either the boiling curve or the heat transfer coefficient. The experimental results are compared to those obtained previously for a dielectric liquid. They are also compared with predictions from several correlations from the literature.

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Shell-Side Condensation Characteristics of R410A on Horizontal Enhanced Tubes

Journal of Heat Transfer ◽

10.1115/1.4045135 ◽

2019 ◽

Vol 142 (1) ◽

Cited By ~ 1

Author(s):

Weiyu Tang ◽

Wei Li

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Mass Flux ◽

Saturation Temperature ◽

Diffusion Resistance ◽

Outer Diameter ◽

Vapor Quality ◽

Enhanced Tubes ◽

The Heat Transfer Coefficient

Abstract An experimental investigation into heat transfer characteristics during condensation on two horizontal enhanced tubes (EHTs) was conducted. All the tested EHTs s have similar geometries with an outer diameter of 12.7 mm, and a plain tube was also tested for comparison. Investigated enhanced surfaces consist of dimples, protrusions, and grooves, which may produce more flow turbulence and enhanced the liquid drainage effect. The effects of mass fluxes and vapor quality were compared and analyzed. Test conditions were as follows: saturation temperature fixed at 45 °C, mass flux varying from 100 to 200 kg m−2 s−1, and vapor quality ranging from 0.3 to 0.8. The heat transfer coefficient was presented, and the results show that the proposed enhanced surfaces seem to have worse performance than the conventional tubes when the mass flux is less than 150 kg m−2 s−1, while one of the enhanced tubes (2EHT-1) produce an enhanced ratio of 1.03–1.14 when G = 200 kg m−2 s−1. Besides, it was found that the heat transfer coefficient increases with increasing vapor quality, which can be attributed to the increasing diffusion resistance. Mass flux seems to have little effect on the heat transfer performance of smooth tubes, while that of 1EHT increases obviously with increasing mass flux, especially for high vapor qualities.

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Experimental Investigation of Shell-Side Flow Condensation on Three-Dimensional Enhanced Surface Tubes

ASME 2020 Heat Transfer Summer Conference ◽

10.1115/ht2020-8987 ◽

2020 ◽

Author(s):

Desong Yang ◽

Zhichuan Sun ◽

Wei Li

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Mass Flux ◽

Three Dimensional ◽

Condensation Heat Transfer ◽

Shell Side ◽

Plain Tube ◽

Side Flow ◽

The Heat Transfer Coefficient

Abstract An experimental investigation of shell-side flow condensation heat transfer was performed on advanced three-dimensional surface-enhanced tubes, including a herringbone micro-fin tube and a newly-developed 1-EHT tube. An equivalent plain tube was also tested for performance comparison. All of the test tubes have similar geometry parameters (inner diameter 11.43mm, outer diameter 12.7mm). Tests were conducted using R410A as the working fluid at a condensation saturation temperature of 45 °C, covering the mass flux range of 10–55 kg/(m2·s) with an inlet quality of 0.8 and an outlet quality of 0.1. Experimental results showed that the plain tube exhibits a better condensation heat transfer performance when compared to the enhanced tubes. Moreover, the mass flux has a significant influence on the heat transfer coefficient for shell-side condensation: the condensation heat transfer coefficient of plain tube decreases when the refrigerant mass flux becomes larger, while the heat transfer coefficient of herringbone tube shows a non-monotonic trend and the heat transfer coefficient of the 1-EHT tube gets higher with increasing refrigerant mass flux. Besides, A new prediction model based on the Cavallini’s equation was developed to predict the condensing coefficient of the three test tubes, and the mean absolute error of the improved equations is less than 4%.

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Steady State Film Boiling Heat Transfer Simulated With TRACE V4.160

Volume 2: Thermal Hydraulics ◽

10.1115/icone14-89494 ◽

2006 ◽

Author(s):

Audrius Jasiulevicius ◽

Rafael Macian-Juan

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Mass Flux ◽

Boiling Heat Transfer ◽

High Mass ◽

Film Boiling ◽

Experimental Database ◽

Boiling Heat Transfer Coefficient

This paper presents the results of the assessment and analysis of TRACE v4.160 heat transfer predictions in the post-CHF (critical heat flux) region and discusses the possibilities to improve the TRACE v4.160 code predictions in the film boiling heat transfer when applying different film boiling correlations. For this purpose, the TRACE v4.160-calculated film boiling heat flux and the resulting maximum inner wall temperatures during film boiling in single tubes were compared with experimental data obtained at the Royal Institute of Technology (KTH) in Stockholm, Sweden. The experimental database included measurements for pressures ranging from 30 to 200 bar and coolant mass fluxes from 500 to 3000 kg/m2s. It was found that TRACE v4.160 does not produce correct predictions of the film boiling heat flux, and consequently of the maximum inner wall temperature in the test section, under the wide range of conditions documented in the KTH experiments. In particular, it was found that the standard TRACE v4.160 underpredicts the film boiling heat transfer coefficient at low pressure-low mass flux and high pressure-high mass flux conditions. For most of the rest of the investigated range of parameters, TRACE v4.160 overpredicts the film boiling heat transfer coefficient, which can lead to non-conservative predictions in applications to nuclear power plant analyses. Since no satisfactory agreement with the experimental database was obtained with the standard TRACE v4.160 film boiling heat transfer correlations, we have added seven film boiling correlations to TRACE v4.160 in order to investigate the possibility to improve the code predictions for the conditions similar to the KTH tests. The film boiling correlations were selected among the most commonly used film boiling correlations found in the open literature, namely Groeneveld 5.7, Bishop (2 correlations), Tong, Konkov, Miropolskii and Groeneveld-Delorme correlations. The only correlation among the investigated, which resulted in a significant improvement of TRACE predictions, was the Groeneveld 5.7. It was found, that replacing the current film boiling correlation (Dougall-Rohsenow) for the wall-togas heat transfer with Groeneveld 5.7 improves the code predictions for the film boiling heat transfer at high qualities in single tubes in the entire range of pressure and coolant mass flux considered.

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Experimental Study on Flow Evaporation Heat Transfer Characteristics Inside Horizontal Three-Dimensional Enhanced Tubes

ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems ◽

10.1115/ipack2018-8454 ◽

2018 ◽

Author(s):

Wei Li ◽

Chuancai Zhang ◽

Zhichuan Sun ◽

Zhichun Liu ◽

Lianxiang Ma ◽

...

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Mass Flux ◽

Three Dimensional ◽

Outer Diameter ◽

Evaporation Heat ◽

Enhanced Tubes ◽

Evaporation Heat Transfer ◽

The Heat Transfer Coefficient

Experimental investigation was performed to measure the evaporation heat transfer coefficients of R410A inside three three-dimensional enhanced tubes (1EHT-1, 1EHT-2 and 4LB). The inner and outer enhanced surface of the 4LB tube is composed by arrays of grooves and square pits, while 1EHT-1 tube and 1EHT-2 tube consist of longitudinal ripples and dimples of different depths. All these tubes have an inner diameter of 8.32 mm and an outer diameter of 9.52 mm. Experiment operational conditions are conducted as follows: the saturation temperature is 279 K, the vapor quality ranges from 0.2 to 0.8, and the mass flux varies from 160 kg/(m2·s) to 380 kg/(m2·s). With the mass flux increasing, the heat transfer coefficient increases accordingly. The heat transfer coefficient of 1EHT-2 is the highest of all three tubes, and that of 1EHT-1 is the lowest. The heat transfer coefficient of 4LB ranks between the 1EHT-1 and 1EHT-2 tube. The reason is that the heat transfer areas of the 1EHT-2 and 4LB tube are larger than that of 1EHT-1 and interfacial turbulence is enhanced in 1EHT-2.

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Study on Flow Boiling Heat Transfer of Carbon Dioxide With PAG-Type Lubricating Oil in Pre-Dryout Region Inside Horizontal Tube

2010 14th International Heat Transfer Conference, Volume 1 ◽

10.1115/ihtc14-23189 ◽

2010 ◽

Cited By ~ 1

Author(s):

Chaobin Dang ◽

Minxia Li ◽

Eiji Hihara

Keyword(s):

Heat Transfer ◽

Carbon Dioxide ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Mass Flux ◽

Boiling Heat Transfer ◽

Flow Boiling ◽

Nucleate Boiling ◽

Flow Boiling Heat Transfer ◽

The Heat Transfer Coefficient

In this study, the boiling heat transfer coefficients of carbon dioxide with a PAG-type lubricating oil entrained from 0 to 5 wt% in a horizontally placed smooth tube with an inner diameter of 2 mm were experimentally investigated under the following operating conditions: mass fluxes from 170 to 320 kg/m2s, heat fluxes from 4.5 to 36 kW/m2, and a saturation temperature of 15 °C. The results show that for a low oil concentration of approximately 0.5% to 1%, no further deterioration of the heat transfer coefficient was observed at higher oil concentrations in spite of a significant decrement of the heat transfer coefficient compared to that under an oil-free condition. The heat flux still had a positive influence on the heat transfer coefficient in low quality regions. However, no obvious influence was observed in high quality regions, which implies that nucleate boiling dominates in the low quality region whereas it is suppressed in the high quality regions. Unlike the mass flux under an oil-free condition, mass flux has a significant influence on the heat transfer coefficient, with a maximum increase of 50% in the heat transfer. On the basis of our experimental measurements of the flow boiling heat transfer of carbon dioxide under wide experimental conditions, a flow boiling heat transfer model for horizontal tubes has been proposed for a mixture of CO2 and polyalkylene glycol (PAG oil) in the pre-dryout region, with consideration of the thermodynamic properties of the mixture. The surface tension and viscosity of the mixture were particularly taken into account. New factors were introduced into the correlation to reflect the suppressive effects of the mass flux and the oil on both the nucleate boiling. It is shown that the calculated results can depict the influence of the mass flux and the heat flux on both nucleate boiling and convection boiling.

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Two Phase Heat Transfer of Ammonia in a Mini/Micro Channel

ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels: Parts A and B ◽

10.1115/fedsm-icnmm2010-30302 ◽

2010 ◽

Author(s):

M. Hamayun Maqbool ◽

Bjo¨rn Palm ◽

R. Khodabandeh ◽

Rashid Ali

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Mass Flux ◽

Experimental Results ◽

Working Fluid ◽

Internal Diameter ◽

Vapour Quality ◽

The Heat Transfer Coefficient

Experiments have been performed to investigate heat transfer in a circular vertical mini channel made of stainless steel (AISI 316) with internal diameter of 1.70 mm and a uniformly heated length of 245 mm using ammonia as working fluid. The experiments are conducted for a heat flux range of 15 to 350 kW/m2 and mass flux range of 100 to 500 kg/m2s. The effects of heat flux, mass flux and vapour quality on the heat transfer coefficient are explored in detail. The experimental results show that the heat transfer coefficient increases with imposed wall heat flux while mass flux and vapour quality have no considerable effect. Experimental results are compared to predictive methods available in the literature for boiling heat transfer. The correlations of Cooper et al. [1] and Shah [3] are in good agreement with our experimental data.

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Experimental Investigation of Condensation Heat Transfer and Adiabatic Pressure Drop Characteristics Inside a Microfin and Smooth Tube

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132517500274 ◽

2017 ◽

Vol 25 (03) ◽

pp. 1750027 ◽

Cited By ~ 3

Author(s):

M. Mostaqur Rahman ◽

Keishi Kariya ◽

Akio Miyara

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Pressure Drop ◽

Transfer Coefficient ◽

Mass Flux ◽

Saturation Temperature ◽

Condensation Heat Transfer ◽

Vapor Quality ◽

Transfer Coefficients ◽

Frictional Pressure Drop

Experiments on condensation heat transfer and adiabatic pressure drop characteristics of R134a were performed inside smooth and microfin horizontal tubes. The tests were conducted in the mass flux range of 50[Formula: see text]kg/m2s to 200[Formula: see text]kg/m2s, vapor quality range of 0 to 1 and saturation temperature range of 20[Formula: see text]C to 35[Formula: see text]C. The effects of mass velocity, vapor quality, saturation temperature, and microfin on the condensation heat transfer and frictional pressure drop were analyzed. It was discovered that the local heat transfer coefficients and frictional pressure drop increases with increasing mass flux and vapor quality and decreasing with increasing saturation temperature. Higher heat transfer coefficient and frictional pressure drop in microfin tube were observed. The present experimental data were compared with the existing well-known condensation heat transfer and frictional pressure drop models available in the open literature. The condensation heat transfer coefficient and frictional pressure drop of R134a in horizontal microfin tube was predicted within an acceptable range by the existing correlation.

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