Improved Energy Efficiency of Mixed Convection Heating Process in Eccentric Annulus

Abdelmlek, Khaoula Ben; Fayçal, Ben Nejma

doi:10.1177/16878140211039150

Cited by 3 publications

(3 citation statements)

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“…is the hydraulic diameter, is the surface temperature of the inner cylinder at a specified axial location and is the bulk temperature, which is calculated as the massweighted average temperature of the air across the annulus at a specified axial location. The average value of the Nusselt number along the inner cylinder is calculated by integrating the local values along the cylinder as: (11) where the axial direction along the cylinders is the z-direction as shown in Figure 1.…”

Section: Mathematical Modelmentioning

confidence: 99%

“…This statement has an agreement with the investigations carried out by Kang et al [9] where a high rotation rate could suppress vortex shedding. Recently, Chithrakumar et al [10] and Khaoula and Faycal [11] considered the mixed convection (free and forced) in annulus which is eccentric with heated rotating inner cylinder. They presented the results to show that maximum energy efficiency is achieved with high values of Rayleigh number and with small eccentricity.…”

Section: Introductionmentioning

confidence: 99%

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Parametric Study of Heat Transfer from An Annulus with Rotating Inner Cylinder

Saeid¹,

Liang²,

Shuib³

2022

JMechE

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The present article presents a parametric study on the forced convection heat transfer from a heated rotating inner cylinder with the stationary outer cylinder in the presence of an axial flow. Both laminar and turbulent flows of air are considered. The following parameters were considered in the present research work: Reynolds number, the rotational speed of the inner cylinder, heat flux dissipated from the inner cylinder in addition to the annulus gap width. The results are presented to show the variation of the Nusselt number with the governing parameters for both laminar and fully turbulent flow. The results of the present study show that increasing either the Reynolds number, rotation speed, and/or the gap distance, leads to improve the cooling and enhancing the heat dissipation from the inner cylinder for both laminar and turbulent flows. The present numerical results show also that various heat flux values from the inner rotating cylinder have a negligible effect on the rate of the cooling process.

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Section: Mathematical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Parametric Study of Heat Transfer from An Annulus with Rotating Inner Cylinder

Saeid¹,

Liang²,

Shuib³

2022

JMechE

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“…With the advent of industrial advancement, the continuation of research and studies of convective heat transfer must meet the requirements of recent environmental and industrial applications in terms of improving thermal performance and energy efficiency of processes. In this context, [26], [27], studied numerically the case of concentric and eccentric annulus respectively. The inner cylinder is supposed to be hot and rotating, however the outer one is cold and immobile.…”

Section: Introductionmentioning

confidence: 99%

Energy Efficiency Analysis of Natural Convection Heat Transfer in Concentric Annulus with Interior and Exterior Grooves

Abdelmlek,

Nejma

2023

1790-5044

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This study is a numerical investigation of the convective heat transfer in motionless concentric annulus composed of two horizontal cylinders, one of which is grooved. The inner cylinder is kept at hot temperature Th and the outer one is kept at cold temperature Tc. The aim of this paper is to analyze the effect of the groove on thermal and dynamic behavior in the annulus when the groove is located on the hot cylinder (inner groove), and when it is located on the cold cylinder (exterior groove). To observe the effect the inner and outer groove on the flow structure and on the heat transfer rate, the groove is positioned at ϕ0=-90̊, -45̊, 0 ̊, 45 ̊, and 90̊. Moreover, the groove size (f) and the radius ratio (e) of the annulus have been changed to investigate their effects on heat transfer rate as well as on the energy efficiency of the process. The results show that the heat transfer rate rises up with the increase of Rayleigh number. It is seen that; in the case of the inner groove; the heat transfer rate reaches a maximum at ϕ0=40̊, whatever the groove size. Furthermore, the energy efficiency of the process is maximum when the inner groove is positioned at ϕ0=90̊, and it increases well with the increase of f. On the other hand, in the case of the exterior groove, the heat transfer rate is practically close to that of non-grooved annulus for f<0.7. A decrease of 34% of the energy efficiency is noticed with the increase of the size of the groove to f=0.7. Our results would be very useful for manufacturers who are looking for increasing the energy efficiency of their process, or also who need to boost or decrease the heat transfer rate depending on the objective of their process.

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