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Capillary-pumped two-phase heat transport technology
Two-phase heat transport technology is based on the use of a continuous evaporation and condensation cycle at the saturation temperature of a selected working fluid. The thermal gradient between the evaporating and condensing section of the two-phase heat transport device is consequently much lower than that of conduction-based devices.

The two-phase flow-based thermal control device which is currently used in almost all satellites is the ammonia based heat pipe. This technology, initially developed for telecommunication satellites in early 1970s, is now fully mature.

Current heat pipe developments at ESA are mainly focussed on performance enhancement and on extension of the upper and lower operating temperature of these devices. In addition, ESA supports the performance optimisation of radiator panels with embedded heat pipes.

Capillary-driven two-phase fluid loop developments were initiated at ESA in the late 1980s and started to gain wider acceptance in the early 2000s. They have other thermal and structural features not provided by the heat pipe systems. In particular, they are an enabling technology and hence baselined as the heat transfer element for deployable radiators.  
Last update: 2 May 2007


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