Accession Number : AD0263465

Title :   HEAT TRANSFER TO CRYOGENIC HYDROGEN AT SUPER-CRITICAL PRESSURES

Corporate Author : AEROJET-GENERAL CORP AZUSA CALIF

Personal Author(s) : THOMPSON,W.R. ; GEERY,E.L.

Report Date : JUL 1960

Pagination or Media Count : 1

Abstract : Heat transfer by forced convection to cryogenic hydrogen at supercritical pressures has been studied experimentally, using a resistanceheated tubular test element. Test pressures were varied from 680 to 1344 psia with fluid bulk temperatures at the test-section inlet ranging from 55 to 102 R. The maximum heat flux obtained was 8.0 Btu/sq. in.-sec, while the maximum wall-to-bulk temperature ratio was 16.5. Heat transfer to hydrogen was found to be characterized by two mechanisms, each differing in its dependence on Reynolds number and the wall-to-bulk temperature ratio. Although mean residence times were of the order of milliseconds, the data indicate that an appreciable fraction of the parahydrogen was converted to the ortho form, the degree of conversion increasing with wall temperature. Support is presented for the Powell hypothesis that a minimum exists in the heat-transfer coefficient near the critical temperature. Further, a second distinct but lesser minimum in the coefficient was found to exist about 50 to 75 R above the critical temperature. The Nikuradse equation was found to satisfactorily relate the friction factor and the bulk Reynolds modulus for supercritical hydrogen. (Author)

Descriptors :   *CRYOGENICS, *HEAT TRANSFER, *HYDROGEN, COOLANTS, HEAT EXCHANGERS, LIQUEFIED GASES, PRESSURE, REYNOLDS NUMBER, ROCKET ENGINES, TEMPERATURE

Distribution Statement : APPROVED FOR PUBLIC RELEASE