Mechanically Pumped Two-Phase Flow Loop Evaporator Development and Performance Evaluations



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50th International Conference on Environmental Systems


Two-phase flow loop offers unique benefits in spacecraft thermal control system. Compared to the passive thermal control, the two-phase flow loop is more suitable for high heat load, high heat flux, and long transport distance applications. Additionally, it has better architecture flexibility and better tolerance to late stage design change. Compared to the single phase thermal control system, the two-phase flow loop offers better temperature uniformity, lower pumping power, and lighter system mass. With these benefits, the prospect of deploying two-phase thermal control technology in high power spacecraft is very promising. In general, there are four major components in the two-phase flow loop; a pump, an evaporator, a radiator/condenser, and a two-phase accumulator. In addition to these hardware, the development of the two-phase thermal control system architecture and system control scheme also play equally important roles in ensuring the system robustness. Collins Aerospace has been working on the two-phase thermal control technology development in the past few years. One of the efforts was to develop an evaporator with the features of high heat load/flux capability, minimum pumping power consumption, light weight structure, and high scalability. This paper reviews the test apparatus and the performance of the evaporators. The heat load was varied from 1,000 W to 8,000 W and the heat flux was varied from 6.5 W/cm2 to 22.6 W/cm2. The heat load was applied to the top, the bottom, or both sides of the evaporator. Water was used as the working fluid and the quality was controlled in the range between 0.1 and 0.8. Using the evaporator interface and outflow temperatures as references, with quality of 0.5 and single-sided heat load of 3,500 W, the 2-inch wide by 12-inch long evaporator thermal resistance is 7.0 x 10-5 �C-m2/W and the hydraulic power is 0.016 W.


Wei-Lin Cho, Collins Aerospace
Gary Adamson, Collins Aerospace, Retired
ICES201: Two-Phase Thermal Control Technology
The 50th International Conference on Environmental Systems was held virtually on 12 July 2021 through 14 July 2021.


Mechanically Pumped Two-Phase Flow Loop, Two-Phase Thermal Control, Evaporator