Browsing by Author "Lefort, Georges"
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Item Deployable Panel Radiator(47th International Conference on Environmental Systems, 2017-07-16) Lecossais, Anthony; Jacquemart, Francois; Lefort, Georges; Dehombreux, Emmanuel; Beck, Felix; Frard, Valerie"The Deployable Panel Radiator (DPR), a premiere in Europe, is finalizing its development with the extensive support of ESA through the ARTES Large Platform Mission by prime contractor Airbus Defence and Space. A DPR will be incorporated into the Eurostar Neo product line catalog. Eurostar Neo is part of the ARTES14 Next Generation Platform element, the ESA program to develop and qualify satellite product lines in the 3 to 6 tons launch mass range by the end of the decade. Telecommunication operators owing for ever increasing payload capability, thermal dissipation has become one of the most significant challenges for satellite manufacturers. Fixed passive radiators on the north and south panels of telecom spacecraft used to be sufficient to radiate heat into space and prevent the spacecraft from overheating. But for missions such as the new generation of Very High Throughput Satellites, typically generating up to 25kW power, traditional radiators are no longer sufficient. In those instances a DPR offers a significant increase of the thermal heat rejection capability, of the order of 2.4 kW per DPR unit. The DPR’s most innovative aspect is its passive circulation system, which allows efficient cooling of the payload thanks to two-phase loop heat pipes. Heat is transported by gaseous ammonia from LHP evaporators located on the payload heat pipes to condensers embedded within a large radiator panel. After condensation, ammonia returns in liquid state to the evaporators thanks to the capillary mesh acting as a passive pump. During launch, each DPR is stowed against the spacecraft body. Once in orbit, it is deployed thanks to a single axis mechanism which incorporates flexible piping for the cooling fluid. The DPR Qualification Model has successfully undergone extensive thermal, functional and mechanical testing."Item Operation of an Eight-Loop Heat Pipe Architecture for High Dissipative Applications(51st International Conference on Environmental Systems, 7/10/2022) Prado Montes, Paula; Lefort, Georges; Pastor Fernández, José Luis; Beck, Felix; Macías Jiménez, SandraArchitectures with several Loop Heat Pipes (LHPs) connected to a network of Heat Pipes (HPs) can be considered as an attractive solution for space missions with highly dissipative equipment onboard. This kind of architecture allows transferring significant heat loads efficiently on long distances towards different cold thermal sinks, while ensuring stable and uniform temperature of the dissipating units. Operation of several LHPs in parallel has been historically considered unstable due to the intrinsic features of the LHP performance during transients and in particular for start-up. A system based on eight LHPs connected to a network of 12 HPs has been defined for the thermal control of all Dual State Solid Power Amplifiers (DSSPAs) in a highly dissipative Active Antenna. The system design has been challenged to cope with stringent operational requirements such as high heat transport capability in the range of 5kW and temperature homogeneity among the DSSPAs, with temperature gradients < 5K. To prove the concept, a dedicated Thermal Model (TM) has been built and tested at different operational scenarios and boundary conditions. The TM consists of eight LHPs distributed on a network of 12 HPs in parallel, each LHP being mounted on six HPs, so that each HP remains in contact with at least three, and up to five, LHP evaporators. The TM has been tested both in vacuum and in climatic chamber. The test sequence included start-up in cold and hot environment and from different initial conditions including dry-out and preconditioning, shut-down tests and performance with several power and sink levels, with and without heat leaks to the reservoir. Start-up and shut down ability of the LHPs, plus reliability of the system operating during steady conditions and transients has been proven.