Experimental investigation on flow characteristics in a narrow annulus

Lu, Guangyao; Wang, Jing

doi:10.1007/s00231-007-0268-1

Cited by 5 publications

(12 citation statements)

References 12 publications

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“…Unlike in the case for a circular tube, where transition based on the friction factor and the heat transfer coefficient from laminar to turbulent starts and ends concurrently, in annular passages, transition based on the heat transfer coefficient often starts earlier than transition based on the friction factor. This is also the case in this study, and reflects similar observations made by Lu and Wang [24,25] for a narrow annulus. The difference in the transitional range behaviour for the heat transfer coefficient and the friction factor is due to the fact that the friction factor is influenced by both the outer and inner wall surfaces, while the heat was only transferred at the inner wall surface (the outer wall being isothermal).…”

Section: Transitional Flow Regime Reynolds Number Limitssupporting

confidence: 93%

“…For experimental studies, only a few references are available in the literature. These include work by Mohammed et al [22], Ciampi et al [23] and Lu and Wang [24,25]. Some of these are briefly discussed here.…”

mentioning

confidence: 96%

“…In their studies, Lu and Wang [24,25] experimentally considered the characteristics of a developing flow with buoyancy-driven secondary flow in narrow annuli in three flow orientations, including a horizontal flow passage layout. Their investigation revealed that heat transfer and flow characteristics in the annular passage differ from those in circular tubes.…”

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confidence: 99%

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Heat transfer and pressure drop in annuli with approximately uniform internal wall temperatures in the transitional flow regime

Ndenguma

Dirker

Meyer

2017

International Journal of Heat and Mass Transfer

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Highlights• Experimental investigation of the transitional flow regime in an annulus for water.• Heated and cooled inner wall uniform wall temperature conditions are studied.• Nusselt number, friction factor and critical Reynolds number results are presented.• Annular dimensions directly impact resultsa new geometric parameter is proposed.• Nusselt number and friction factor correlations are developed. AbstractAn experimental study was conducted to determine the lower and upper Reynolds number limits of the transitional flow regime, and the characteristics of the heat transfer coefficients and friction factors for annular passages with different hydraulic diameters and diameter ratios in the transitional flow regime. Water was used in this investigation during isothermal, heating and cooling cases. Four horizontal concentric counter-flow tube-in-tube heat exchangers with conventional inlet geometries were considered to obtain the required data.The flow was both hydrodynamic and thermally developing, and the transitional flow was composed of mixed and forced convection types. The wall temperature on the inner surface of the annular passages was approximately uniform, while the outer surface was isothermal.Average Nusselt numbers were obtained for both the heating and cooling cases, while friction 1 Corresponding author: jaco.dirker@up.ac.za, Mechanical and Aeronautical Department, University of Pretoria, Private Bag X20, Hatfield 0028, RSA. 2 factors were obtained for heating, cooling and isothermal adiabatic conditions. Isothermal adiabatic condition was considered for reference purposes. The geometric size of the annular passage and direction of the heat flux (heating and cooling cases of annular fluid) had a significant influence on the heat transfer coefficients, friction factors and Reynolds number span of the transitional flow regime. The annular geometric parameters that represent the geometric size of the annular passage were proposed and found to describe the heat transfer coefficient and friction factors well. Subsequently, correlations for predicting the Nusselt numbers and friction factors in the transitional flow regime were developed.

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Section: Transitional Flow Regime Reynolds Number Limitssupporting

confidence: 93%

mentioning

confidence: 96%

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Heat transfer and pressure drop in annuli with approximately uniform internal wall temperatures in the transitional flow regime

Ndenguma

Dirker

Meyer

2017

International Journal of Heat and Mass Transfer

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“…The criterion for instability is based on the energy gradient method for parallel flow instability. It is shown that the Stable for all Re 20.7 370 370 Table 1 Comparison of the critical Reynolds number and the energy gradient parameter K max for plane Poiseuille flow and pipe Poiseuille flow as well as for plane Couette flow [19,20]. U is the averaged velocity, 0 u the velocity at the mid-plane of the channel, D the diameter of the pipe, h the half-width of the channel for plane Poiseuille flow (L=2h) and plane Couette flow.…”

Section: Discussionmentioning

confidence: 99%

Determining the critical condition for turbulent transition in a full-developed annulus flow

Dou

Khoo

Tsai

2010

Journal of Petroleum Science and Engineering

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“…The selected grids consist of 15 and 200 cells, respectively in the radial and axial directions. Figure 2 compares the experimental results of frictional pressure drop at various Reynolds numbers [25] with the predicted results. While Fig.…”

Section: Grid Test and Results Validationmentioning

confidence: 94%

Numerical Study of Laminar Forced Convection of Water/Al2o3 Nanofluid in an Annulus with Constant Wall Temperature

Kashani¹,

Jalali-Vahid

Hossainpour

2013

IIUMEJ

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Laminar forced convection of a nanofluid consisting of water and Al2O3 in a horizontal annulus has been studied numerically. Two-phase mixture model has been used to investigate thermal behaviors of the nanofluid over constant temperature thermal boundary condition and with different volume concentration of nanoparticles. Comparisons with previously published experimental and analytical works on flow behavior in horizontal annulus show good agreements between the results as volume fraction is zero. In general convective heat transfer coefficient increases with nanoparticle concentration.Â ABSTRAK: Kertaskerja ini mengkaji secara numerik olakan paksa bendalir lamina yang menganduangi air dan Al2O3 didalam anulus mendatar. Model campuran dua fasa digunakan bagi mengkaji tingkah laku haba bendalir nano pada keadaan suhu malar dengan kepekatan nanopartikel berbeza. Perbandingan dengan karya eksperimen dan analitikal yang telah diterbitkan menunjukkan bahawa kelakuan aliran didalm anulus mendatar adalah baik apabila pecahan isipadu adalah sifar. Pada amnya, pekali pemindahan haba olakan meningkat dengan kepekatan nanopartikel.Â KEYWORDS: nanofluid; volume concentration; heat transfer enhancement; laminar flow convection; annulus

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Experimental investigation on flow characteristics in a narrow annulus

Cited by 5 publications

References 12 publications

Heat transfer and pressure drop in annuli with approximately uniform internal wall temperatures in the transitional flow regime

Heat transfer and pressure drop in annuli with approximately uniform internal wall temperatures in the transitional flow regime

Determining the critical condition for turbulent transition in a full-developed annulus flow

Numerical Study of Laminar Forced Convection of Water/Al2o3 Nanofluid in an Annulus with Constant Wall Temperature

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