The deterioration of chemicals contained in safety devices is an important issue because such devices must be ready for emergencies and should remain functional for a long period of time, even when exposed to degrading environments. In this study, we focused on the influence of ozone disinfection on chemicals present in safety devices as ozone can be used for virus inactivation in compartments housing these devices. Specifically, we conducted accelerated deterioration tests to evaluate the effects of ozone exposure on guanidine nitrate (GN).
Under the experimental conditions of this study, ozone-containing water deteriorated GN, whereas no change was observed in GN exposed to dry ozone. The ion chromatography (IC) analysis of the deteriorated product suggested that GN decomposed into nitrate ions, while capillary electrophoresis (CE) revealed a transformation of guanidine ions into ammonium ions. These results imply that GN deterioration produces ammonium nitrate. Additionally, ultraviolet-visible spectroscopy revealed the reaction products between GN and ozone, which were considered electrically neutral because of their absence in the results of IC and CE analyses.
In a differential accelerating rate calorimeter, decomposition started at a lower temperature for the deteriorated GN than for the pristine sample. This indicates that the deterioration products affected the thermal decomposition behavior of GN. This change in exothermic and pressure-release behavior is considered to have an impact on the performance of pyrotechnics using GN.

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In the flow field of a rotating detonation engine (RDE), the detonation wave propagates through the reaction with the continuously injected fuel and oxidant mixture. In the previous research using the actual RDE, due to insufficient mixing, combustor shape, centrifugal force, and so forth, the detonation wave velocity generated in RDE is usually significantly lower than the characteristic Chapman-Jouguet (C-J) velocity for the corresponding mixture. In order to elucidate the effect of incomplete fuel mixing on detonation propagation inside RDE, a closed linear combustor (CLC) with doublet injectors that can change the injection angle was constructed. A lower plenum pressure was examined because supersonic fuel injection shock waves would affect detonation wave propagation. To verify feasibility of the experiment and obtain the predicted value, numerical analysis of detonation wave plunging entry combustible gas jet train of the premixed fuel and non-premixed fuel at three injection angles (perpendicular to the bottom wall, 70 degrees, and 45 degrees) were carried out. The fuel and oxidant use Ethylene (C₂H₄) and Oxygen (O₂) respectively. The results showed that the effects of detonation wave pressure on the injectors arranged along the propagation direction of blast wave are obviously less than that of the jet ports arranged perpendicular to the bottom wall and opposite directions of detonation propagation. Although the detonation propagation velocity of non-premixed fuel is lower than that of premixed fuel, it could also reach more than 90% of the C-J velocity after the promotion of mixing. Compared with pure non-premixed gas, the detonation velocity increases by about 50%. Therefore, the performance is expected to be improved by creating a structure in the RDE that allows the fuel and oxidizer to intersect in advance and be injected in the direction of the detonation wave propagation. The numerical results also confirm that the reflection wave from the top of the CLC does not affect the propagation and visualization of the detonation wave.

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Ammonium dinitramide (ADN)-based high energetic ionic liquids are promising new liquid rocket propellants that can replace hydrazine due to their high energy density and handling properties. In this study, aiming at realizing stable ADN supplies, we focused on the synthesis of dinitramide salts using a small (μL to several mL) continuous reactor. Due to the small capacity of the reactor, it can efficiently remove the heat generated from the reaction, and the dinitramide salts can be safely synthesized. To investigate the feasibility of the synthesis with the small continuous reactor system, we fabricated a test reactor with transparent resin and tried to synthesize dinitramic acid (HDN). The ultraviolet (UV) spectrometry of the products at the reactor outlet showed that they absorbed UV rays at 〜285 nm. The absorption of the dinitramide anion was observed even at higher synthetic temperatures than those of typical syntheses in batch reactors. These results showed that the fabricated small continuous reactor allows the safe synthesis of dinitramide salts even at relatively high temperatures due to its high heat removal efficiency.

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Understanding gel fuel combustion behavior is pivotally important for future engineering practice. This study experimentally investigated the combustion behavior of non-metallized and metallized gel droplets. Pure ethanolmethylcellulose gel was used to represent non-metallized gel. Mixed ethanol-methylcellulose gel with 10% aluminum (Al) powder was used to represent metallized gel. Gel droplet combustion experiments were conducted at an initial ambient temperature of approximately 700 (±20) °C under an air convective condition. The initial diameter of droplets used for combustion experiments was 2.25 ± 0.11 mm. Observations revealed different combustion behaviors of nonmetallized and metallized gel droplets. The combustion of metallized gel droplets exhibited a particular phenomenon: an Al agglomeration period before combustion ceased. This finding suggests that adding aluminum powder in ethanolmethylcellulose gel might reduce the droplet ignition delay time and might increase the droplet burning time, thereby allowing more energy to be released during combustion.

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