Experimental results are presented for friction factor and surface finish measurements on eight graphite tubes machined to give a range of surface finishes from smooth up to the maximum roughness likely to occur in a reactor.
Correlations are given which allow estimation of friction factor from graphite surface finish measurements.
The results are compared with those obtained by Nikuradse in his sand-grain roughness tests. Except at low values of es+, agreement is good, enabling the heat transfer similarity law of Dipprey and Sabersky to be used to predict any increases in Stanton number due to surface roughness.
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References
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NikuradseJ.‘Strömungsgesetze in rauhen rohren’, Trans. NACA TM 1292 1933.
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WarburtonC.‘The surface roughness of graphite and its effect on friction factor’, CEGB Rep. RD/B/N2219 1972.
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ColebrookC. F.‘Turbulent flow in pipes, with particular reference to the transition region between the smooth and rough pipe laws’, J. Instn civ. Engrs1938–3911, 133–56.
