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.