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The Two-Phase Fluid Loop (TPFL) System is a heat transport system for future large spacecraft, using latent heat of coolant. TOSHIBA Co. has developed a ground test facility capable of dissipating a 5kw heat load and tested the components of that facility since 1988. As a next phase, static characteristics of the TPFL system are being studied. In this paper, static behaviors under heat load variation are presented as results of the experimental study and the numerical simulation. For the experimental study, the above-mentioned ground test facility was used. In this facility, heat is finally dissipated to the heat exchanger using brine as a heat sink. In order to determine static behaviors for an actual radiator heat rejection system used in orbit, numerical simulation was carried out. To confirm the analytical model used in the numerical simulation, the numerical result and the experimental result were compared.

Self-rewetting fluids, i.e. dilute aqueous alcoholic solutions with unique surface tension behavior, have been proposed as working fluids for terrestrial and space heat pipes. Experiments have been carried out in normal gravity and in low-gravity conditions with tubular heat pipes, thin flat heat pipes for thermal management in electronic devices, and flexible, inflatable and deployable radiator panels for space applications. Self-rewetting heat pipes exhibit, in general, better thermal performances in comparison with water heat pipes. Current developments are focused on self-rewetting brines, studied as candidate potential heat transfer fluids for space applications. Activities are in progress to perform experiments in space with a small technological payload onboard a microsatellite developed by the Italian Space Agency.

A multi-objective optimization model using a piston behavior simulation for the prediction of NV, friction and scuffing was created. This model was used to optimize the piston skirt form, helping to enable well-balanced forms to be sought. Optimization calculations, involving extended analyses and numerous design variables, conventionally necessitate long calculation times in order to achieve adequate outcomes. Because of this, in the present project data was converted into functions in order to help enable the complex piston skirt form to be expressed using a small amount of coefficients. Using the limit values for manufacturability and the degree of contribution to the target functions, the scope of design variables was restricted, and the time necessary for the analysis was significantly reduced. This has helped to enable optimal solutions to be determined within a practical time frame.

A new concept of the anti-freeze PEFC stack has been demonstrated. Anti-freeze concepts consist of an antifreeze coolant system and the new humidification method called “Jiko-kashitu”, which eliminates the liquid water channels required for humidificaion. The antifreeze stack has the cell stack assembly equipped with an anti-freeze coolant system and the humidifying section recycling of product water. The fresh air humidified by the Jiko-kashitu method is supplied to the cell stack assembly. The exhaust air including product water is introduced into the Jiko-kashitu section and product water permeates the membrane to humidify the fresh air. The anti-freeze stack also employs the low height design fitting under a passenger space by use of high aspect ratio separators. A 3kW class anti-freeze PEFC stack was fabricated, and the anti-freeze concepts were evaluated.