Mechanically pumped two-phase heat transport systems are currently developed to meet the high power and long transport distance requirements of thermal management systems for future large spacecraft.
Capillary pumped systems are being developed for applications with special requirements concerning microgravity disturbance level, temperature stability and controllability.
As two-phase flow and heat transfer in a low-gravity environment is expected to differ from terrestrial behaviour, two-phase heat transport system technology has to be demonstrated in orbit. Therefore the Dutch-Belgian Two-Phase eXperiment TPX has been developed within the ESA In-Orbit Technology Demonstration Programme.
TPX is a two-phase ammonia system, flown in the 5ft3 gaseous nitrogen filled Get Away Special canister G557, aboard STS-60. The system, being a reduced-scale capillary pumped two-phase loop with a flat and a cylindrical capillary evaporator and an actively controlled reservoir (for loop temperature setpoint control), also included downscaled versions of mechanically pumped two-phase loop components: multichannel condensers and vapour quality sensors, plus a controllable 3-way valve for control exercises.
The objectives of the autonomously running experiment and its actual flight configuration (with own power supply, data handling and experiment control) are presented.
Preliminary results of the flight data analysis are compared with pre-launch predictions and test results.