Experimental study on condensation flow patterns inside inclined U-bend tubes

Mozafari, M.; Akhavan-Behabadi, M.A.; Qobadi-Arfaee, H.; Hanafizadeh, Pedram; Fakoor-Pakdaman, M.

doi:10.1016/j.expthermflusci.2015.05.003

Cited by 12 publications

(6 citation statements)

References 14 publications

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“…Convective heat transfer in inclined tubes has long been considered. One of the most important applications of the inclined tube is their use in solar collectors and refrigerant distillation in condensers of heat transfer systems [1] to [3], since introducing the subject of adding nanoparticles to the base fluid to improve the efficiency of heat transfer systems, extensive studies were done both numerically and experimentally in horizontal tubes with different boundary conditions and various cross sections [4] to [6]. Saha and Paul [7] studied numerically turbulent flow forced convection heat transfer of two nanofluids and concluded that by increasing the Reynolds number, the Nusselt number increases.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of the Effect of the Reynolds Numbers on Thermal and Hydrodynamic Parameters of Turbulent Flow Mixed Convection Heat Transfer in an Inclined Tube

Vahidinia¹,

Miri²

2015

SV-JME

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A numerical investigation of the effect of the Reynolds number on the thermal and hydrodynamic parameters of mixed convection heat transfer of the water-Al 2 O 3 nanofluid turbulent flow in an inclined circular channel is the subject of this article. The upper wall of the channel was under non-uniform heat flux and its lower part was isolated. The two-phase mixture model, the finite volume method, and the secondorder upstream difference scheme were used to solve the governing equations. After reviewing the results, it was found that by increasing Reynolds number, the convective heat transfer coefficient and shear stress increase, but the surface friction coefficient decreases. In the case of Nusselt number and the surface friction coefficient, some equations were extracted.

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Section: Introductionmentioning

confidence: 99%

Numerical Study of the Effect of the Reynolds Numbers on Thermal and Hydrodynamic Parameters of Turbulent Flow Mixed Convection Heat Transfer in an Inclined Tube

Vahidinia¹,

Miri²

2015

SV-JME

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“…The inclination effect on flow patterns for low mass flux R134a (52-225 kg/m 2 s) flow in U-bend tubes was visually observed and analyzed [20]. The findings of the research showed that the flow pattern was strongly influenced by gravitational and centrifugal forces, surface tension, shear stress and thus the inclination of the tube.…”

Section: Literature Studiesmentioning

confidence: 98%

“…For U-bend tubes, stratified and stratified-wavy flow regimes appeared at low-vapour qualities, annular flow was observed at high-vapour qualities where the effects of gravitational and centrifugal forces could be neglected. In the same types of channels, with the increasing interfacial shear stress at high mass fluxes, the liquid separated from the channel walls and this phenomenon provided a basis for more stable flow characteristics and disappearing slug and slug/stratified-wavy flows [20].…”

Section: Literature Studiesmentioning

confidence: 98%

Comprehensive Review on the Flow Characteristics of Two-Phase Flows in Inclined Tubes

Karademir¹,

Ozcelik²,

Açıkgöz³

et al. 2021

Journal of Thermal Engineering

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This paper presents a comprehensive review of research works on condensation and boiling heat transfer characteristics in horizontal, vertical and inclined tubes both smooth and enhanced. Although there are many studies examining two-phase flows inside tubes, it is almost impossible to find such a comprehensive study for two-phase flow in tubes. Moreover, while number of the studies concerning condensation or boiling inside tubes are limited, the present study covers almost all studies of condensation and boiling inside inclined tubes. Previous studies are classified into many subtitles according to configuration (horizontal, vertical or inclined) and roughness (smooth or enhanced) as well as aim of the study (researching the effect of parameters on the heat transfer coefficient, pressure drop or evaluation of prediction correlation). Such a wide range of classification and scope have no done before. Condensation and boiling phenomena are of great importance in heat exchangers, cooling systems, etc. due to their wide utilization in those devices. Additionally, two-phase flow and the associated heat transfer are becoming increasingly important in industrial applications because the heat transfer coefficient in twophase flows is much higher than in single-phase flows. In this research, major topics such as heat transfer, pressure drop, friction factor and void fraction were studied using active and passive techniques in the literature. The fluids used in the reviewed studies diverse in a very wide range. For pure refrigerants (single component-fluorocarbon refrigerant),

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“…Latent heat stored in the TES Maximum heat storage capacity o f TES (14) Figure 8 shows temporal plots of SHR for all of the studied cases so far. It could be seen that quick, full solidifications could be achieved when both PCMs were almost equally involved in the energy recovery during the whole discharging process (case-4 and case-6).…”

Section: Shr =mentioning

confidence: 99%

“…Therefore, novel techniques could be used for an accelerated solidification or melting of the PCMs. Eccentric configuration of the tubes in horizontal TES systems has been identified as an efficient, economical, practical, yet simple technique to improve the rate of phase change process [14]. Senthil [15] experimentally investigated the effect of heat transfer fluid (HTF) tube orientation in a horizontal TES unit filled with PCM.…”

Section: Introductionmentioning

confidence: 99%

Simulation Study of Solidification in the Shell-And-Tube Energy Storage System with a Novel Dual-PCM Configuration

Mozafari

Lee

2022

Energies

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This study proposes a novel dual-PCM configuration with outstanding solidification response in a horizontal shell-and-tube energy storage system. To demonstrate that the proposed PCM configuration is superior in its thermal responses, results from a range of numerical simulations are presented and compared between different configurations of dual-PCM. As the melting/solidus point is a crucial factor for the solidification rate, dual PCMs are chosen such that the average of their melting point is equal to the melting point of the single-PCM in the reference case. Additionally, equal-area sectors are considered for all cases to ensure the same quantities of PCMs are compared. The temporal liquid fraction and temperature contours reveal that solidification is delayed in the upper half of the system due to strong natural convection motions. Therefore, a dual-PCM configuration is offered to improve the solidification rate in this region and accelerate the full solidification process. Results show that placing a PCM with a lower solidus point in the lower half or an annulus-shaped zone around the cold tube can save the full recovery time up to 8.51% and 9.36%, respectively. The integration of these two strategies results in a novel and optimum design that saves the solidification time up to 15.09%.

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Experimental study on condensation flow patterns inside inclined U-bend tubes

Cited by 12 publications

References 14 publications

Numerical Study of the Effect of the Reynolds Numbers on Thermal and Hydrodynamic Parameters of Turbulent Flow Mixed Convection Heat Transfer in an Inclined Tube

Numerical Study of the Effect of the Reynolds Numbers on Thermal and Hydrodynamic Parameters of Turbulent Flow Mixed Convection Heat Transfer in an Inclined Tube

Comprehensive Review on the Flow Characteristics of Two-Phase Flows in Inclined Tubes

Simulation Study of Solidification in the Shell-And-Tube Energy Storage System with a Novel Dual-PCM Configuration

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