Analysis of conduction - natural convection conjugate heat transfer in the gap between concentric cylinders under solar irradiation

Dong Chul Kim, Young Don Choi

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Although, in general, most of concentric cylinders used in engineering applications are heated non-uniformly, studies on the natural convection in the air layer between the cylinders have been performed only for the uniform heating so that it is difficult to apply the results to the real cases. In the present study, the effects of material property of outer cylinder and the air gap thickness between cylinders on the natural convection are investigated by computational fluid dynamics and experimental means. Namely, conduction-natural convection conjugated heat transfer in the concentric cylinders, gun and shield tube, under solar irradiation, is analyzed numerically and the various predictions on the resultant thermal deformations of gun are compared to the experimental data with variation of the gap thickness of cylinders and material properties of shield tube. Results show that larger the thermal conductivity of shield tube, smaller the Nusselt number variations of gun and shield tube surfaces. This is due to that balance of conduction in the cylinders and natural convection in the gap between inner and outer cylinders may increase the uniformity of the air layer temperature. High thermal conductivity of shield tube inhibits the natural convection in the air layer and there exists a gap thickness that exerts an influence critically on the thermal deformation of gun.

Original languageEnglish
Pages (from-to)1247-1258
Number of pages12
JournalInternational Journal of Thermal Sciences
Volume48
Issue number6
DOIs
Publication statusPublished - 2009 Jun 1

Fingerprint

concentric cylinders
Engine cylinders
Natural convection
free convection
heat transfer
Irradiation
Heat transfer
conduction
irradiation
tubes
Air
air
Thermal conductivity
Materials properties
thermal conductivity
Nusselt number
computational fluid dynamics
Computational fluid dynamics
convection
Heating

Keywords

  • Inner cylinder (gun)
  • Natural convection
  • Outer cylinder (shield tube)
  • Solar radiation

ASJC Scopus subject areas

  • Engineering(all)
  • Condensed Matter Physics

Cite this

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abstract = "Although, in general, most of concentric cylinders used in engineering applications are heated non-uniformly, studies on the natural convection in the air layer between the cylinders have been performed only for the uniform heating so that it is difficult to apply the results to the real cases. In the present study, the effects of material property of outer cylinder and the air gap thickness between cylinders on the natural convection are investigated by computational fluid dynamics and experimental means. Namely, conduction-natural convection conjugated heat transfer in the concentric cylinders, gun and shield tube, under solar irradiation, is analyzed numerically and the various predictions on the resultant thermal deformations of gun are compared to the experimental data with variation of the gap thickness of cylinders and material properties of shield tube. Results show that larger the thermal conductivity of shield tube, smaller the Nusselt number variations of gun and shield tube surfaces. This is due to that balance of conduction in the cylinders and natural convection in the gap between inner and outer cylinders may increase the uniformity of the air layer temperature. High thermal conductivity of shield tube inhibits the natural convection in the air layer and there exists a gap thickness that exerts an influence critically on the thermal deformation of gun.",
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N2 - Although, in general, most of concentric cylinders used in engineering applications are heated non-uniformly, studies on the natural convection in the air layer between the cylinders have been performed only for the uniform heating so that it is difficult to apply the results to the real cases. In the present study, the effects of material property of outer cylinder and the air gap thickness between cylinders on the natural convection are investigated by computational fluid dynamics and experimental means. Namely, conduction-natural convection conjugated heat transfer in the concentric cylinders, gun and shield tube, under solar irradiation, is analyzed numerically and the various predictions on the resultant thermal deformations of gun are compared to the experimental data with variation of the gap thickness of cylinders and material properties of shield tube. Results show that larger the thermal conductivity of shield tube, smaller the Nusselt number variations of gun and shield tube surfaces. This is due to that balance of conduction in the cylinders and natural convection in the gap between inner and outer cylinders may increase the uniformity of the air layer temperature. High thermal conductivity of shield tube inhibits the natural convection in the air layer and there exists a gap thickness that exerts an influence critically on the thermal deformation of gun.

AB - Although, in general, most of concentric cylinders used in engineering applications are heated non-uniformly, studies on the natural convection in the air layer between the cylinders have been performed only for the uniform heating so that it is difficult to apply the results to the real cases. In the present study, the effects of material property of outer cylinder and the air gap thickness between cylinders on the natural convection are investigated by computational fluid dynamics and experimental means. Namely, conduction-natural convection conjugated heat transfer in the concentric cylinders, gun and shield tube, under solar irradiation, is analyzed numerically and the various predictions on the resultant thermal deformations of gun are compared to the experimental data with variation of the gap thickness of cylinders and material properties of shield tube. Results show that larger the thermal conductivity of shield tube, smaller the Nusselt number variations of gun and shield tube surfaces. This is due to that balance of conduction in the cylinders and natural convection in the gap between inner and outer cylinders may increase the uniformity of the air layer temperature. High thermal conductivity of shield tube inhibits the natural convection in the air layer and there exists a gap thickness that exerts an influence critically on the thermal deformation of gun.

KW - Inner cylinder (gun)

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KW - Outer cylinder (shield tube)

KW - Solar radiation

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