Design optimization of a hydrogen advanced loop heat pipe for space-based IR sensor and detector cryocooling

Abstract

Next generation space infrared sensing instruments and spacecraft will require drastic improvements in cryocooling technology in terms of performance and ease of integration. Projected requirements for cryogenic thermal control systems are: high duty cycle heat loads, low parasitic heat penalty, long transport distances, highly flexible transport lines, and lower cooling temperatures. In the current state of cryocooling transport technology, cryogenic Loop Heat Pipes (CLHPs) are at the forefront of intensive research and development. CLHPs are capable of dispersing heat quickly from an IR heat source and transporting it to remotely located cryocoolers via small and flexible transport lines. Circulation of working fluid in a CLHP is accomplished entirely by capillary action developed in fine pore wicks of the system capillary pumps. Thus they contain no mechanical moving parts to wear out or to introduce unwanted vibrations to the spacecraft. A recently developed CLHP using Hydrogen as the working fluid performed extremely well in the temperature range of 20-30K under the most severe operating conditions. However, it was not optimized for spacecraft applications due to cost and schedule constraints of the initial research phase. Design optimization of the Hydrogen Advanced Loop Heat Pipe is the main objective of the follow-on research. Chief among the system improvements is the weight and volume reduction of the loop components.