Mccreight, C. R. — Page 3 | Engineering Papers

NASA NTRS1977

Development of a thermal diode heat pipe for cryogenic applications

The paper describes the development of a cryogenic thermal diode heat pipe for space flight applications. The diode has ethane working fluid, and uses the liquid blockage technique with an internal blocking orifice, to accomplish shutoff in the reverse mode. The pipe is 0.635 cm OD by 75.82 cm long including a 2.54 cc excess liquid reservoir. Experimental data are presented for forward mode throughput vs tilt, film coefficients, and reverse mode characteristics. Transport capacity is 1000 w-cm at 2.5 cm tilt. Evaporator and condenser film coefficients were 0.92 and 1.64 w/sq cm K, respectively.

Quadrini, J. A.↗

NASA NTRS1976

Development and test of two flexible cryogenic heat pipes

Results are presented for a comprehensive test program directed toward determining the physical and thermal performance of two flexible cryogenic heat pipes that can provide a highly efficient thermal link between a detector and a space radiator or other cooling system in spacecraft applications. A 100-200 K high-power heat pipe is tested with methane at 100-140 K while a 15-100 K low-temperature pipe is designed for operation with nitrogen and oxygen and is optimized for oxygen in the range 75-90 K. Parametric performance and design tradeoff studies are carried out to determine the optimum geometry and materials for the container and wicking systems. A spiral multiwrap wick in conjunction with braided bellows appears to be a workable solution to the problem of developing highly flexible heat transport devices for cryogenic applications.

Wright, J. P.↗