Publication Date:
2019-06-26
Description:
Local values of heat transfer coefficients have been measured experimentally for helium and hydrogen gas flowing through an electrically heated inconel tube. The experiment was conducted primarily to determine the effect on the heat transfer coefficient of a large density change, radially, in the heat transfer fluid. This large density change was accomplished with relatively high surface temperatures as compared to fluid bulk temperatures or more commonly referred to as high surface to fluid bulk temperature ratio. The large temperature ratio was achieved by precooling the gas with liquid nitrogen. Data were measured for local values of surface to fluid bulk temperature ratios up to 4.5, Reynolds numbers in the turbulent flow region, surface temperatures up to 2300 R, heat flux up to 1,600,000 Btu/(hr)(sq ft) and length to diameter ratio of 250. A comparison of this data with the conventional heat transfer correlation equation (Dittus-Boelter eq.) is shown on a curve of Nusselt number divided by Prandtl number versus the Reynolds number. The gas properties were evaluated at the film temperature and the Reynolds number was modified by evaluating the velocity term at the fluid bulk temperature and the density at the film temperature.
Keywords:
Fluid Mechanics and Thermodynamics
Type:
E-1721
,
GRC-E-DAA-TN67415
Format:
application/pdf
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