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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).

A two-dimensional model to calculate the radial heat transfer coefficient in a heat pipe evaporator with trapezoidal grooves is extended to highly efficient so-called ‘Re-Entrant’ groove geometries. Results from the model are compared with experimental values. Good agreement is found. For further theoretical studies the heat transfer model is combined with liquid flow characteristics in axial groove direction. Based on these numerical studies, an advanced capillary structure is developed to improve the heat transfer coefficient. The new structure consists of the Re-Entrant grooves with additional micro grooves which are manufactured on top of them. It is modeled in a first attempt by superposition of two two-dimensional heat transfer models. A parameter study shows that for certain dimensions of the micro grooves the overall evaporative heat transfer coefficient considerably increases compared to the standard Re-Entrant groove geometry.

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.

An ESA technology programme led to the successful development of an aluminum extruded heat pipe family based on a multi re-entrant grooves design and using ammonia as working fluid. This family, called High Capacity Grooved Heat Pipe (HGP), has been submitted to a space qualification programme according to ESA standards (ESA PSS-49; see ref.[1]), which aimed to fulfill an as large as possible range of potential applications. Therefore, four heat pipe diameters (11 mm, 15 mm, 20 mm and 25 mm), two heat pipe outer shapes (circular, saddles integrated) and two heat pipe configurations (straight, bent) have been selected for going into this space qualification. The space qualification programme, started in 1994, ended up early 1997. The present paper presents the HGP heat pipe family characteristics and the space qualification programme.

The Water Supply Assembly (WSA) is part of the Liquid Management Section (LMS) of the Hermes Environmental Control and Life Support Subsystem (ECLSS) (see ref. [1] and [2]). The WSA has to provide pure water for drinking and food preparation (rehydratation of dry food and beverage powder) and to provide pure water for hygiene purposes (oral hygiene and towel wetting). To obtain different desired temperatures (as well as different quantities of water to be dispensed), a heating device, using electrical foils, and a cooling device, using a water/water heat exchanger have been designed with regard to the critical mass and power requirements. Two dispensers are used to fill food/beverage or hygiene (towels) containers. As part of the Hermes C1 phase, breadboard models of the heating device (heater) and of the cooling device (chiller) have been manufactured and functionally tested.

In the frame of an ESA technology program, the development of a High Capacity Grooved Heat Pipe (HGP), based on the thermal requirements of the next generation of telecommunication satellites, was contracted to SABCA. Different promising concepts and methods of groove technology were reviewed. A trade-off and design study was performed on potential HGP concepts, taking into account theoretical performances (on earth and in micro-gravity), ease of manufacturing and of assembly as well as the heat pipe working reliability and priming capability. The two finally selected concepts were aluminium extruded heat pipes (outer diameter of 25 mm, vapour core diameter of 15 mm), based on a multi re-entrant grooves concept or on a mixed rectangular/re-entrant grooves concept.