Thermodynamic optimization of free convection film condensation on a horizontal elliptical tube with variable wall temperature

Yang, Sheng‐An; Li, Guan-Cyun; Yang, Wen‐Jei

doi:10.1016/j.ijheatmasstransfer.2007.03.019

Cited by 13 publications

(6 citation statements)

References 15 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%

“…Two correlations were proposed for the prediction of the friction factor and the Nusselt number. Yang et al [10] focused on the thermodynamic analysis of saturated vapour flowing slowly onto and condensing on an elliptical tube with variable wall temperature, Qu et al [11] presented a numerical solution for film condensation on a vertical plate sintered with metallic foam.…”

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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“…As it is noticed before, in the current study in addition to the study of the external mixed convective heat transfer for pure and nanofluid flow over a cylinder with different cross sections, the second law of thermodynamic or the entropy generation analysis which is proportional to the irreversibility has been investigated. Due to the fact that, the maximum friction entropy generation is of order of 10 and in compare with the thermal entropy production is negligible, hence in the current study the total entropy is considered equivalent to the heat transfer generated entropy (Yang, Hung et al 2007). The entropy generation for pure fluid and nanofluid with = 0.03 is shown in Fig.…”

Section: Fig 4 Convection Heat Transfer Coefficient For Pure Free Cmentioning

confidence: 99%

“…The energy quality analysis is a relatively modern method to provide an effective way to optimize the performance of a thermal system based on the principle of entropy generation minimization. Yang et al (2007) analyzed the entropy generation of the laminar film condensation on an ellipsoid under the effect of the non-isothermal wall temperature for different ellipticity. The results illustrated that, the entropy generation due to heat transfer in comparison to the film flow friction is superior in most cases.…”

Section: Introductionmentioning

confidence: 99%

Mixed Convection Heat Transfer of Al2O3 Nanofluid on the Elliptical Shapes: Numerical Study of Irreversibility

Khajeh¹,

Jahanshaloo²,

Ebrahimi³

et al. 2018

JAFM

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In this study the 2D laminar and steady water-based Al2O3 nanofluid flow over a cylinder with circular, horizontal and vertical elliptical cross section by constant surface temperature boundary condition has been studied. The main goal of this research is to investigate the effects of different natural and mixed convection heat transfer mechanisms on the convective heat transfer coefficient, and the entropy generation due to the thermal and frictional origination. Conservation equations of the mass, momentum and energy under the assumption of incompressible, Newtonian nanofluid, by using the homogeneous single phase method have been solved. The impact of considered parameters in this study (alteration in cross section, convective flow direction and volume fraction of nano particles) in enhancing the heat transfer rate is studied in association with the entropy generated value in each case. Based on the results, the vertical elliptical cross section, in comparison with others, shows the highest entropy generation value and the heat transfer coefficient in all considered mechanisms. Moreover, mixed convection heat transfer type 2, in which the force flow is perpendicular to the buoyant flow direction, has the highest entropy generation and heat transfer rate for all cross sections. In addition, in all cases in the presence of the nanoparticles, the heat transfer rate and entropy generation increases.

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“…The entropy generation number was found to be a function of the Rayleigh, Brinkman numbers and geometrical parameters (ellipticity). Moreover, Yang et al [23] have studied thermodynamic optimization of free convection film condensation on a horizontal elliptical tube with variable wall temperature. Their results indicated that the optimal entropy generation number is proportional to amplitude of non-isothermal wall temperature variation.…”

Section: Introductionmentioning

confidence: 99%

Entropy generation of forced convection film condensation on a horizontal elliptical tube

Esfahani

Modirkhazeni

2012

Comptes Rendus. Mécanique

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The aim of this study is to analyze the entropy generation number in forced convection film condensation on a horizontal isothermal elliptical tube. A numerical approach has been used to investigate how parameters, including ellipticity of ellipse, Reynolds and Brinkman numbers affect the irreversibility. The results show that the minimization of total entropy generation number (N S ) can be achieved by reducing the values of Reynolds and Brinkman numbers. Also, it was concluded that the effect of ellipticity on total entropy generation number is significant for e > 0.7 and increasing ellipticity, increases the amount of N S .

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Thermodynamic optimization of free convection film condensation on a horizontal elliptical tube with variable wall temperature

Cited by 13 publications

References 15 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

Mixed Convection Heat Transfer of Al2O3 Nanofluid on the Elliptical Shapes: Numerical Study of Irreversibility

Entropy generation of forced convection film condensation on a horizontal elliptical tube

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