New equations for Nusselt number and friction factor of the annulus side of the conically coiled tubes in tube heat exchangers

Ali, Mohamed; Rad, Milad Mansouri; Nuhait, A.; Almuzaiqer, Redhwan; Alimoradi, Ashkan; Tlili, Iskander

doi:10.1016/j.applthermaleng.2019.114545

Cited by 21 publications

(8 citation statements)

References 74 publications

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“…(17c), and eq. (26-29) and the corresponding diagrammatic representations in Figures (7)(8)(9)(10)(11) and Figure 13, have shown that their input to the total amount of entropy generation was little short of zero. It is evident that there were obtained values of the entropy generation from 10 −12 to 10 −7 W/mK, but at the same time it has also been concluded that the contribution of the biggest gradient ∂vx/∂y, although also imperceptible in relation to the total entropy production, is 10 5 higher in comparison to other velocity gradients.…”

Section: Discussionmentioning

confidence: 99%

“…In order to include the effects of interfacial slip, Pati et al [8] extended Nusselt's theory on film condensation over vertical surfaces and brought enhancement in Nusselt number as a consequence of an effective interfacial slip as compared to that in case of without slip. Ali et al [9] numerically simulated the fluid flow and the turbulent/laminar water heat transfer through the annulus side of the conically tube. Two correlations were proposed for the prediction of the friction factor and the Nusselt number.…”

Section: Introductionmentioning

confidence: 99%

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Entropy Analysis of Complete Condensation of Saturated Steam on a Vertical Wall Using Nusselt Velocity and Temperature Profile in a Condensate Layer

Rauch¹,

Mudrinić²,

Galović³

2021

J. sustain. dev. energy water environ. syst.

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In this paper an analytical model for calculation of entropy production for Nusselt model of condensation of pure substance vapour is given. Model development starts from basic two-dimensional integral equation for entropy production and describes film condensation on a vertical wall. Model covers entropy production, which is a result of two-dimensional heat transfer in a condensate layer, existence of velocity gradient and condensate layer viscosity. Entropy contribution of each of the members is explicitly derived in a closed form and the results of calculation are shown in the appropriate diagrams. Diagrams present film condensation of dry saturated water steam and dry saturated ammonia steam, both with saturation temperature of 100 °C with surface wall temperature of 98.5 °C. Obtained equations and presentation of the related results have shown that dominant entropy production is directly connected only with heat conduction in y-axis direction, where y-axis corresponds with thickness of condensate layer.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Entropy Analysis of Complete Condensation of Saturated Steam on a Vertical Wall Using Nusselt Velocity and Temperature Profile in a Condensate Layer

Rauch¹,

Mudrinić²,

Galović³

2021

J. sustain. dev. energy water environ. syst.

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“…where D is the diameter of the conical spiral tube and L the length of the conical spiral tube. The data obtained by Ali et al were employed to confirm the CFD results [33]. The heat exchanger consists of a conical coil with inner and outer diameters of 8 and 14 mm, respectively, conical angle of 40°, coil pitch of 20 mm, and height of 100 mm.…”

Section: Computational Fluid Dynamicsmentioning

confidence: 92%

Computational Fluid Dynamics and Fuzzy Logic for Modeling Conical Spiral Heat Exchangers

Soltanian

Beigzadeh

2023

Chem Eng & Technol

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Computational fluid dynamics and fuzzy logic (FL) modeling methods were used to estimate heat transfer and fluid flow characteristics in conical spiral tubes. The effects of coil pitch p and cone angle θ at Reynolds numbers Re of 1500–5500 on flow and heat transfer were investigated. Water with an inlet temperature of 298 K was considered as the working fluid, and a constant wall temperature of 398 K was used in the study. FL was used to predict the Nusselt number and friction factor in conical spiral tubes as functions of Re, θ, and p. FL is an efficient method for predicting complex systems and is a valuable complement to classical hard computing techniques. The purpose of the study was to find a relationship between heat exchanger parameters and performance characteristics. It was also investigated how the FL expert system plays an important role in predicting heat transfer performance.

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“…They reported that the conical coil tubes improved melting rate compared to normal coil in the percentage of 22%. Ali et al 9 performed a numerical investigation to find out the heat transfer and fluid flow through the annulus of conical tube heat exchangers. The results showed that the Nusselt number and friction factor enhanced by 37.17% and 15.51% as the cone angle changed from 0° to 90°.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis on heat transfer enhancement of Al₂O₃ nanofluid in the flattened conically coiled tubes

Solanki¹,

Ram²,

Siddharth³

2022

Heat Trans

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Enhancement in the heat transfer of the working fluid flowing inside the tube is achieved by modification of tubes and changing the direction of fluid flow. For this purpose, the straight tube can be changed into a conical coil tube, thereby, heat transfer is increased due to the centrifugal effect caused by the curvature of the tube. Furthermore, the circular cross-section of the tube is modified into an oblong shape for more heat transfer enhancement. In this study, the numerical heat transfer and pressure drop characteristics of Al 2 O 3 -water nanofluids in the flattened conically coiled tube are studied. The effect of the aspect ratio, cone angle, coil pitch, and solid volume fraction of nanofluids on heat transfer and pressure drop are examined. It is found that the heat transfer coefficient and pressure drop increase with the rise of aspect ratio, Reynolds number, and solid volume fraction of nanofluid, while it decreases with the increment of cone angles and coil pitches of conical coil tube. Furthermore, the effect of aspect ratio on the heat transfer enhancement factor, pressure drop ratio, and thermal performance index for Al 2 O 3 -water nanofluid are presented.

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New equations for Nusselt number and friction factor of the annulus side of the conically coiled tubes in tube heat exchangers

Cited by 21 publications

References 74 publications

Entropy Analysis of Complete Condensation of Saturated Steam on a Vertical Wall Using Nusselt Velocity and Temperature Profile in a Condensate Layer

Entropy Analysis of Complete Condensation of Saturated Steam on a Vertical Wall Using Nusselt Velocity and Temperature Profile in a Condensate Layer

Computational Fluid Dynamics and Fuzzy Logic for Modeling Conical Spiral Heat Exchangers

Numerical analysis on heat transfer enhancement of Al₂O₃ nanofluid in the flattened conically coiled tubes

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New equations for Nusselt number and friction factor of the annulus side of the conically coiled tubes in tube heat exchangers

Cited by 21 publications

References 74 publications

Entropy Analysis of Complete Condensation of Saturated Steam on a Vertical Wall Using Nusselt Velocity and Temperature Profile in a Condensate Layer

Entropy Analysis of Complete Condensation of Saturated Steam on a Vertical Wall Using Nusselt Velocity and Temperature Profile in a Condensate Layer

Computational Fluid Dynamics and Fuzzy Logic for Modeling Conical Spiral Heat Exchangers

Numerical analysis on heat transfer enhancement of Al2O3 nanofluid in the flattened conically coiled tubes

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Product

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About

Numerical analysis on heat transfer enhancement of Al₂O₃ nanofluid in the flattened conically coiled tubes