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One of the current applications for cryogenic heat pipes is the European astronomy satellite INTEGRAL where two aluminium / ammonia axially grooved heat pipes will be used to transport a heat load of 20 W from an intermediate stage at 210K to a radiator. A prototype heat pipe of 1.65m long, with a 14 mm outside diameter, has been manufactured and tested. The extrapolated 0g maximum heat transport capability at 200K is 60 W.m. Tests have shown the reliability of the ammonia heat pipe to work close to its freezing point (down to 197K) and its ability to thaw within a few minutes using the right procedure. A development model with the same heat pipe profile but filled with ethane has shown a maximum heat transport capability of 19 W.m at 200K under 5 mm adverse tilt (46 W.m for the ammonia) and just a few watts at ambient temperature. This confirms the suitability of the ammonia heat pipe for the INTEGRAL application, where the operating temperature is [200K;300K].

This paper presents the last developments which have been performed at SABCA under internal funding, and the application of this work on the Technological Telecommunication Satellite STENTOR. The High Performance Capillary Pumped Loop ( HPCPL ) has been defined to get a reliable operation mode under a very wide range of operation conditions. Preliminary results have been already presented (ref. (1)), showing the high performances and the reliable functional characteristics of the HPCPL. The present paper emphasises the last developments which have been performed at SABCA.

This paper presents the development program of a High Performance Heat Pipe (HPHP) whose first application is aboard the satellite STENTOR, the French Advanced Telecommunication Satellite. A trade-off study has been performed to select the most appropriate high performance heat pipe design to meet the requirements (maximum heat transport capability of at least 500W.m). The selected one is the aluminium axially grooved heat pipe. A numerical model has been used to optimise the grooves geometry, which consists of divergent entrance passageways (0.4mm width) and a circular trough. As a first development tests model, a HPHP of 17 mm outer diameter, 2.8 m long and 470g/m has been manufactured and tested. The first tests results have shown a heat transport capability of 600 W.m horizontally at +20°C and 400 W.m under a tilt height of 5 mm.