Koji Fujisato

Bio: Koji Fujisato is an academic researcher from University of Tokyo. The author has contributed to research in topics: Ammonium dinitramide & Combustion. The author has an hindex of 3, co-authored 8 publications receiving 42 citations. Previous affiliations of Koji Fujisato include Japan Aerospace Exploration Agency.

Condensed Phase Behavior in the Combustion of Ammonium Dinitramide

Abstract: This paper reports on the thermal and combustion behaviors of ammonium dinitramide (ADN). The thermal behavior is measured by a pressure thermogravimetric analysis (TGA) at pressures below 8 MPa. The burning rates of pure ADN and ADN/ammonium nitrate (AN) mixtures are measured in the range 0.2–12 MPa, and the burning temperature profiles are obtained using thermocouples with diameters of 5 and 25 μm. This report mainly focuses on the condensed-phase behavior in the vicinity of a burning surface. The temperature profiles are complicated because the ADN decomposition and AN dissociation compete during the condensed phase, and the bubbles of the decomposition gas and gas-phase flame also affect the surface temperature. AN addition helps to understand the effects of AN during the condensed phase, and it was shown that the burning temperature rises to the critical temperature of AN. Based on these experimental results, the pressure dependency of the burning rates is also discussed.

Role of Additives in the Combustion of Ammonium Dinitramide

Abstract: The thermal decomposition behavior and combustion characteristics of mixtures of ammonium dinitramide (ADN) with additives were studied. Micrometer-sized particles of Al, Fe2O3, TiO2, NiO, Cu(OH)NO3, copper, CuO, and nanometer-sized particles of aluminum (Alex) and CuO (nano-CuO) were employed. The thermal decomposition was measured by TG-DTA and DSC. The copper compounds and NiO lowered the onset temperature of ADN decomposition. The heat value of ADN with Alex was larger than that of pure ADN in closed conditions. The burning rates and temperature of the pure ADN and ADN/additives mixtures were measured. CuO and NiO enhance the burning rate, particularly at pressures lower than 1 MPa, because of the catalyzed decomposition in the condensed phase; the other additives lower the burning rate. This negative effect on the burning rate is explained based on the surface temperature measurements by a physicochemical mechanism, which involves a chemical reaction, a phase change of the ammonium nitrate, and the blown-off droplets of the condensed phase.

Nitrogen-Based Fuels: A Power-to-Fuel-to-Power Analysis.

Abstract: What are the fuels of the future? Seven representative carbon- and nitrogen-based fuels are evaluated on an energy basis in a power-to-fuel-to-power analysis as possible future chemical hydrogen-storage media. It is intriguing to consider that a nitrogen economy, where hydrogen obtained from water splitting is chemically stored on abundant nitrogen in the form of a nontoxic and safe nitrogen-based alternative fuel, is energetically feasible.