In this paper a first experimental attempt is described in which heat conduction through rarefied air contained between two concentric cylinders is analysed. The heat transfer between a heated platinum wire having a diameter (d) of 0.15 mm, disposed along the axis of a cylindrical shell in stainless steel having an inner diameter (D) of 100 mm, and a surrounded rarefied gas has been studied experimentally. The ratio between the outer and inner diameter of the annular region filled by the gas is large (D/d=667). In the annular region filled with air the pressure was varied by using a vacuum pump from atmospheric value down to 10-3 mbar. Temperature differences between the wire and the external stainless steel wall in the range 50-125 K were imposed and the heat power transferred from the wire to the surround was measured as a function of the gas pressure starting from air at atmospheric conditions down to 10-3 mbar. The experimental results were compared with the numerical results obtained using a linear Shakhov kinetic model. A good agreement between the numerical results and the experimental results were observed for DT=50 and 75 K; on the contrary, for DT>75 K the experimental heat flux was larger than the numerical values. The results suggest the need of an improved accuracy in the experimental tests.

H. Chalabi, L. Saraceno, G. Boccardi, G.P. Celata, M. Lorenzini, D. Valougeorgis, et al. (2012). HEAT CONDUCTION IN AN ANNULAR GAP FILLED WITH A RAREFIED GAS. BOLOGNA : Esculapio.

HEAT CONDUCTION IN AN ANNULAR GAP FILLED WITH A RAREFIED GAS

LORENZINI, MARCO;MORINI, GIAN LUCA
2012

Abstract

In this paper a first experimental attempt is described in which heat conduction through rarefied air contained between two concentric cylinders is analysed. The heat transfer between a heated platinum wire having a diameter (d) of 0.15 mm, disposed along the axis of a cylindrical shell in stainless steel having an inner diameter (D) of 100 mm, and a surrounded rarefied gas has been studied experimentally. The ratio between the outer and inner diameter of the annular region filled by the gas is large (D/d=667). In the annular region filled with air the pressure was varied by using a vacuum pump from atmospheric value down to 10-3 mbar. Temperature differences between the wire and the external stainless steel wall in the range 50-125 K were imposed and the heat power transferred from the wire to the surround was measured as a function of the gas pressure starting from air at atmospheric conditions down to 10-3 mbar. The experimental results were compared with the numerical results obtained using a linear Shakhov kinetic model. A good agreement between the numerical results and the experimental results were observed for DT=50 and 75 K; on the contrary, for DT>75 K the experimental heat flux was larger than the numerical values. The results suggest the need of an improved accuracy in the experimental tests.
2012
Proceedings of 30th UIT Heat Transfer Conference
99
105
H. Chalabi, L. Saraceno, G. Boccardi, G.P. Celata, M. Lorenzini, D. Valougeorgis, et al. (2012). HEAT CONDUCTION IN AN ANNULAR GAP FILLED WITH A RAREFIED GAS. BOLOGNA : Esculapio.
H. Chalabi; L. Saraceno; G. Boccardi; G.P. Celata; M. Lorenzini; D. Valougeorgis; G.L. Morini
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/116948
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