Process of monopropellant flow and catalytic decomposition reaction in micro/nano pores of catalyst
Monopropellant energy belongs to gas energy.Unlike conventional energy that relies on oxygen combustion to release energy,it generates high-temperature and high-pressure gas by catalytic decomposition of energetic liquid chemicals without air,which flows through the Laval nozzle to generate thrust or blow the turbine output shaft power.The characteristics are high reliability,fast response,low cost,and unrestricted flight altitude.It is often used to maintain the satellite orbit and provide the emergency power unit for aerospace equipment.With start-up of this power system,the liquid monopropellant enters the packed bed and contacts with the catalyst particles,and then immerses into the micro/nano pores of the catalyst carrier under the action of capillary force.The high-temperature and high-pressure small molecule gas phase is generated with being activated and decomposed by precious metal nanoparticles.With the influence of catalyst pore structure,size,and surface activity,when the gas production rate of catalytic decomposition inside the pore is greater than the outward movement speed of the fluid,the internal pressure in the pore will sharply increase,and even damage the carrier to deactivate.In this paper,the Poiseuille flow is used to describe the flow of gas-phase products in catalyst pores,the Newton's second law is employed to analyze the movement of gas-liquid interface driven by capillary force,and the gas production rate is predicted through reactant diffusion reaction model.The phenomena of flow,catalytic reaction and gas-phase pressure formation process in the catalyst micro/nano pores is investigated during the initiation of hydrazine propellant catalytic decomposition reaction.The physical phenomenon of catalyst destruction and deactivation caused by the excessive pressure in the pores is analyzed during the initiation process,a theoretical basis for designing and optimizing the catalyst pore structures is provided for decomposing monopropellant.
Poiseuille flowcapillaryhydrazine decompositiondiffusionreactioncatalyst poresmass transfer
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