Microgravity Performance of a Structurally Embedded Oscillating Heat Pipe

The oscillating heat pipe is a novel, simply formed, wickless heat pipe that relies on the phase-change-induced motion of a contained working fluid to transport heat between the evaporator (hot end) and condenser (cold end). The improved heat transfer capability, simplicity, and reduced mass of oscillating heat pipes have led to great interest in the oscillating heat pipe. This paper details the terrestrial and microgravity validation of an ultrasonic consolidation manufactured structurally embedded oscillating heat pipe. It is shown that 1) for conditions in which an oscillating heat pipe is terrestrially orientation-independent, it is also likely to be gravity-independent, and 2) for conditions in which an oscillating heat pipe is not terrestrially orientation-independent, it is likely to perform better in microgravity than in a terrestrial environment. Additionally, this test campaign provides evidence that the “knee” found in most oscillating heat pipe performance versus input heat curves roughly corresponds to the point at which 1) oscillating heat pipe performance variation drops off, 2) oscillating heat pipe performance becomes orientation-independent, and 3) the oscillating heat pipe performance becomes gravity-independent. These results can be used to better predict oscillating heat pipe performance using terrestrial test data.