Catalyst bed multi-objective optimization

Abstract

The main aim of this paper is to present of hydrazine monopropellant catalyst bed optimization methodology. To this end, the main parameters of hydrazine catalyst bed in optimization are decomposition products properties, molecular weight, specific heat ratio and their temperature as function of hydrazine decomposition and ammonia dissociation. These parameters are function of catalyst type, size, and geometry, reaction chamber pressure, and propellant dwell time. Also the objective functions in the optimization are catalyst bed’s weight and performance. First one, a parametric study on hydrazine decomposition products as a function of catalyst bed design has been done. Catalyst bed output temperature, specific heat ratio and molecular weight were calculated as hydrazine and Ammonia dissociation ratio. Thermo chemical result shows that best specific velocity is attained when %25 of ammonia is allowed to dissociate. Pellet diameter, bed loading factor and thrust chamber pressure are assumed as the preliminary design parameters of the catalyst bed to find the catalyst bed length and pressure drop. Finally a numerical simulations, one dimensional, steady state, adiabatic, homogeneous, creeping and uniform flow at axial sections or Plug flow that has chemical reaction across a constant cross-sections catalytic bed, for different pellet diameters, loading factor and chamber pressure, have been carried out with the help of a validated formulations. According to this study, catalyst bed length and pressure drop will increase as the pellet diameter or bed loading increases. However the increase of chamber pressure will lead to the lessening catalyst bed length and pressure drop, but this influence is ignorable.