Composition Optimization of a Hypergolic Green Propellant Based on Monoethanolamine and N-Butanol

Abstract

Satellite attitude-control thrusters design depends on a trade-off between minimum impulse bit and specific impulse (Isp), where pulse maneuvers width rely on a combination of the delay of the hydraulic system (feed tubes and valves) and the ignition delay time (IDT) of the propellant being used. The most well-grounded propellants in this situation are hydrazine and nitrogen tetroxide. However, their high toxicity makes satellites integrations costly and environmentally hazardous. In order to replace these propellants, studies are focusing on the development of new hypergolic green propellants, the majority of which use hydrogen peroxide in high concentration as an oxidizer. The hypergolic reaction between a n-butanol-monoethanolamine blend and hydrogen peroxide was supported in this study by the use of copper nitrate trihydrate as a catalyst. The central composite design (CCD) method was applied to find an optimized composition fuel using 90% hydrogen peroxide as oxidizer. The optimization had two outcomes, for the IDT (31.5% n-butanol, 60% monoethanolamine (MEA) and 8.5% copper nitrate with 20 ms of IDT) and for the theoretical Isp (36% n-butanol, 60% MEA and 4% copper nitrate, with 26 ms of IDT). For the IDT optimization an oxidizer-fuel ratio (O/F) of 4 was chosen, using CEA NASA software, to achieve the maximum theoretical Isp (Ispth) of 170.64 s and for the Ispth optimization an O/F of 4.4 was selected for the same purpose, reaching an Isp of 171.58 s. In line with the results of the study, n-butanol can be used as an additive in catalytically promoted MEA to enhance the freezing point, IDT, viscosity, and ρIsp of the hypergolic pair.

Keywords: Green propellant, High-test peroxide, In-space propulsion