Cryogenic Loop Heat Pipe

Cryogenic heat pipes are typically characterized by their low heat transport capability, resulting from the low surface tension and the low latent heat of their working fluids. These heat transfer limits restrict the amount of heat which can be removed from the device being cooled and/or the allowable separation between the heat source and the sink. Loop Heat Pipes offer significant improvements in heat transport over conventional heat pipes, due to their fine-pored wick structures and liquid and vapor transport lines which are optimized to minimize pressure drop. Loop Heat Pipes have demonstrated their performance advantages at ambient temperature, and have proven to be self-priming, reliable heat transfer devices. The primary goal of the proposed program is to extend this technology to cryogenic temperatures while maintaining the reliability of the ambient temperature devices. A prototype Loop Heat Pipe will be developed in Phase I, with the design goal of improving heat transport capability over state-of- the-art cryogenic heat pipes by an order of magnitude or more. Demonstration tests will characterize the prototype's steady state performance capabilities, as well as its startup behavior. The test results will also be used to validate/update existing analytical models.