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Alcatel Space Cannes has successfully designed, manufactured and ground tested a two-LHP lightweight and high performance deployable radiator (“DELPHRAD”) in the frame of a development program co-funded by ESA. DELPHRAD is a follow-up of the STENTOR deployable radiator flight experiment sponsored by CNES (“Centre National d'Etudes Spatiales”; French National Space Agency). The STENTOR and DELPHRAD LHPs were designed, manufactured and delivered by EHP Nivelles (formerly SABCA Brussels). DELPHRAD features significantly lower mass budget than that of STENTOR with slightly better thermal performance. The considerable mass improvement is achieved essentially by the direct condensation thermal concept and the use of corrugated flexible lines. Some technological innovations contribute to facilitate the deployable radiator thermal sub-system manufacturing and its integration in a satellite system.

This paper describes two possible modelling approaches (ESATAN and ESATAN/FHTS) for the thermo-hydraulic simulation of capillary driven fluid loops. The respective advantages and disadvantages of the approaches are discussed and are illustrated by an Industrial application, the development of a Deployable Radiator by the European consortium Astrium.

Necessity of thermal control of dissipative units located on the earth panel and thermally linked to the North and South radiators of a telecommunication satellite has been identified since many years ago. The thermal control of TV SAT TDF platforms was defined using this concept, but necessitated a complex heat pipe networks with on-ground test constraints. The emergence of the capillary-pumped two-phase loop authorises to perform the same function using one item with virtually no on-ground test constraints. Since 1995, Alcatel Space Cannes (formerly Aerospatiale Cannes), sponsored by CNES, have developed a STENTOR (“Satellite de Télécommunication pour l'Expérimentation de Nouvelles Technologies en Orbite”) 1000 W CPL. The ground qualification has been completed in 1999 and the flight qualification is planned late 2000 (launch of STENTOR satellite).

Future telecommunication and constellation satellites share a common objective to improve their thermal control performances when compared to the current state of the art. They are increasingly demanding in heat transport and thermal dissipation. Thus the use of classical thermal devices such as heat pipes or typical radiators are not sufficient anymore for the overall spacecraft thermal control. Therefore, the expected thermal control needs in the near future have motivated and directed, since about 5 years, new developments as e.g. Loop Heat Pipes. This technology is now almost mature and the industrialisation phase is being started. Indeed, as they give valuable possibilities and advantages to the thermal design of the platform, the LHPs constitute the most promising system to ensure particularly: □ The North / South radiator thermal coupling.

Deployable radiators (DRs) have been in development at Alcatel Space Cannes (formerly Aerospatiale Cannes) since the 1980s to respond to the increasing need of additional heat rejection area. In 1980-1985, Alcatel Space Cannes, sponsored by Centre National d'Etudes Spatiales (CNES), defined, manufactured and ground-tested a 250 W thermal rotating joint DR. Since 1995, Alcatel Space Cannes, sponsored by CNES, have developed a STENTOR («Satellite de Télécommunication pour l'Expérimentation de Nouvelles Technologies en Orbite») 600 W Loop Heat Pipe (LHP)-based DR. The ground qualification will be completed mid 2000 and the flight qualification is planned late 2000 (launch of STENTOR satellite). Late 1998, Alcatel Space, co-funded by the European Space Agency (ESA), started the development of a Deployable Lightweight High Performance Radiator (DELPHRAD). The 1200 W DR will be ground-tested by mid 2001.

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.

ESA/ESTEC funded two-phase heat transport activities for spacecraft thermal control started in the mid 1980's. A number of different two-phase loops, using either a mechanical pump or driven by a capillary pumped evaporator, were designed, assembled and tested successfully in the past years. The transported power levels were from a few hundred watts up to 10 kW over distances of some meters up to several tens of meters. The working fluid was either Freon or Ammonia. Within ESA's Technology Demonstration Programme (TDP1), a first two-phase experiment (TPX) for flight as a GAS-payload on the US Shuttle was designed and has been successfully flown on STS-60 in February 1994.