Nitrous Oxide Based Green Propellants: Fuel Selection and Miscibility Analysis Method

Kurzfassung

Over the past 25 years, the search for safe, high-performance spacecraft propellants has highlighted nitrous oxide (N2O) as one promising alternative to the toxic but efficient and state-of-the-art hydrazine-based propellants. Monopropellant N2O offers key advantages such as low toxicity, self-pressurization and high specific impulse but requires high temperatures for its decomposition to start and can exhibit low combustion efficiency. This study explores premixed N2O-fuel blends as potential monopropellants with the aim of lowering ignition temperatures while ensuring efficiency and safety. Therefore, the focus is on blends close to the Lower Explosion Limit (LEL), where small amounts of fuels are added to N2O. To define and characterize such mixtures, a preliminary fuel selection process is performed and suitable candidates for blending with N2O are identified on defined criteria. The selection results in compounds from the family of the hydrocarbons, alcohols, hydrides and silanes. In addition, a test-bench has been developed to evaluate the miscibility of these mixtures to ensure homogeneous blending and prevent phase separation. The results can provide insights into assessing the range of mixture ratios below the explosion limit that yields functional blends.