Sodium heat pipe with sintered wick and artery: Effects of noncondensible gas on performance

High performance heat pipes with arteries are being designed into space nuclear power systems. Artery depriming and subsequent heat pipe failure can occur if noncondensible gas comes out of solution in sufficient quantities to terminate artery liquid return to the evaporator. This paper describes results of analyses and tests to quantify the conditions for which dissolved gas will come out of solution and shutdown the artery. Results show that a stainless steel/sodium heat pipe will operate reliably when gas concentrations in the liquid are kept at a partial pressure of 0.01 bar or less. For example, the heat pipe survived over 25 cycles of start‐up from the frozen condition being heated to over 800 °C with an evaporator heat flux of 45 W/cm2 with the evaporator elevated 40‐cm above the condenser.