THERMAL CONTROL AND POWER FLATTENING FOR RADIOISOTOPIC THERMODYNAMIC POWER SYSTEM

摘要

A thermal control device utilizing the heat pipe principle. Heat receiving and heat rejecting surfaces are spaced from each other along the length of the heat pipe. In a preferred form, a radioisotope fuel capsule is in thermal conducting relationship with the heat receiving surface and a noncondensible gas is mixed with the working fluid of the heat pipe. A noncondensible gas automatically expands as the threshold temperature of the system drops to block off more of the heat rejecting surface. In other alternate preferred embodiments, a nonvaporizable liquid is utilized in lieu of a noncondensible gas to reduce the area of the heat receiving surface as the threshold temperature of the system drops or a second material is mixed with the working fluid which changes to a solid phase to block the flow of the working fluid between the heat rejecting and heat receiving surfaces as the threshold temperature of the system drops.