2014-10-202014-10-202014-07-13978-0-692-38220-2ICES-2014-136http://hdl.handle.net/2346/59591Tucson, ArizonaThe 44th International Conference on Environmental Systems was held in Tuscon, Arizona, USA on 13 July 2014 through 17 July 2014.H.J. van Gerner, National Aerospace Laboratory NLR, NetherlandsR.C. Van Benthem, National Aerospace Laboratory NLR, NetherlandsJ. van Es, National Aerospace Laboratory NLR, NetherlandsD. Schwaller, European Space Agency, NetherlandsS. Lapensée, European Space Agency, NetherlandsThe selection of a suitable fluid is one of the first and most important steps for the design of a thermal control system. For example, for a heat pipe it is important to use a fluid with a high surface tension and heat of evaporation, and a low viscosity. These characteristics can be combined in a ‘figure of Merit’. This figure of Merit is used to pre-select a number of fluids, after which these fluids are further investigated for material compatibility, safety, radiation hardness etc. This systematic approach results in the selection of the most favourable fluid for each application. In this paper, the fluid selections for heat pumps and pumped loops (both single- and two-phase) are discussed. It is explained for instance why CO2 is used in the thermal control system of AMS02 (which was launched with the space shuttle in May 2011 and subsequently mounted on the International Space Station). Also discussed is the selection of Galden HT80 for ESA’s single-phase Mechanically Pumped Fluid Loop (MPFL) and the selection of isopentane for an ESA Heat Pump application.application/pdfengPresentation