Orifice Blocks Heat Pipe in Reverse Mode

Abstract

High forward-mode conductance is combined with rapid reverse-mode shutoff in a heat pipe originally developed to cool spacecraft payloads. A narrow orifice within the pipe "chokes off" the evaporator if heat sink becomes warmer than source. During normal operation, with source warmer than sink, orifice has little effect. Design is simpler and more compact than other thermal-diode heat pipes and requires no special materials, forgings, or unusual construction techniques.