Development of High-Performance Green-Monopropellant Thruster with Hydrogen Peroxide and Ethanol

Green liquid monopropellant thrusters provide an alternative to toxic hydrazine. A premixed liquid monopropellant based on hydrogen peroxide with ethanol blending was suggested to replace hydrazine in this research. The maximum theoretical vacuum specific impulse was 282s for a certain mixture ratio. A 10-N-scale monopropellant thruster was used for performance evaluation. Platinum with porous gamma-phase alumina support was used as a catalyst. A preliminary firing test was performed for 5s with propellant A, which had 181s of vacuum specific impulse. Catalytic combustion occurred without an additional igniter with 87.7% of C* efficiency in a preliminary firing test. Propellant B, which had 214s of vacuum specific impulse and 276(gs)/cm3 of vacuum density specific impulse, was selected as an alternative to hydrazine. A thruster firing test was performed for 5s, the C* efficiency was measured as 95.3%, and the chamber-pressure oscillation was approximately +/- 13%. To reduce combustion instability, lanthanum hexaaluminate (a high-thermal-resistant catalyst support) was applied in an additional firing test. The pressure oscillation was measured as +/- 3.8%, with 92.8% of C* efficiency in an additional firing test. These results demonstrated the feasibility of an ethanol-blended hydrogen peroxide thruster as a high-performance and green-propellant thruster for space missions.