Library Subscription: Guest

ISSN Online: 2377-424X

ISBN Print: 0-89116-130-9

International Heat Transfer Conference 6
August, 7-11, 1978, Toronto, Canada

DYNAMIC TESTING OF A CRYOGENIC HEAT PIPE/RADIATOR

Get access (open in a dialog) DOI: 10.1615/IHTC6.2770
pages 105-110

Abstract

An experimental investigation was performed to determine the dynamic characteristics of two fixed conductance cryogenic heat pipe/radiators, 1.3 and 6.4 meters long. Included was the response of Freon-13 and nitrogen filled pipes to step changes in evaporator power, as well as response during natural and (evaporator) powered cooldown to the cryogenic regime. Key features of the transient response, subsequent to step power changes that encompassed 2.2 and 62.6 watts (about 87°K to 230°K), include the following: (1) Pipe response was well-behaved with monotonic changes in temperature levels. (2) Once start-up occurred, a relatively large attached distributed mass had a minor effect on pipe performance. (3) Pipe response times for large power changes were fairly long, being measured in hours. (4) It was possible to speed elevation of the pipe temperature by overdriving the evaporator. Preliminary findings on natural cooldown to the cryogenic regime indicated that, under certain conditions, heat pipe/radiators will fail to start naturally as a result of radiator drop-out. Powering of the evaporator during cooldown was shown to be one method of achieving startup. It was also demonstrated that a common Lobar Wick design can be utilized to provide thermal control over an extremely wide temperature range of at least 74-230°K.