Turbulent diffusion of heat and mass in catalytic reactors for hydrazine decomposition

Effects of Catalyst Bed Failure on Thermochemical Phenomena for a Hydrazine Monopropellant Thruster Using Ir/Al2O3 Catalysts

“…In this study, we separated a satellite thruster into two parts: the catalyst bed and the nozzle section. Because the decomposition chamber was filled with catalyst pellets, the catalyst bed was modeled as a one-dimensional porous medium …”

“…The governing equations for the catalyst bed were separated into catalyst-surface equations (eqs –) and gas-phase equations (eqs –). , One of the most important properties for characterizing transport phenomena between catalyst pellets and the gas phase is the specific surface area. In our study, the specific surface area was defined as the ratio of the pellet surface area to the pellet volume, and it could be varied with respect to catalyst bed porosity and pellet size.…”

“…The decomposition kinetics of hydrazine can be described by a two-step reaction model (eqs and ): 2 normalN 2 normalH 4 → 2 NH 3 + normalN 2 + normalH 2 2 NH 3 → normalN 2 + 3 normalH 2 Numerous researchers have proposed an Arrhenius-type reaction constant, i.e., a pre-exponential factor A and an activation energy E a or activation temperature T a for a heterogeneous reaction of hydrazine and ammonia. − ,,, It is important to use the proper reaction constants when carrying out numerical analysis. The kinetic parameters used by Kesten, as well as Shankar et al, were also empirically determined by trial and error. The new catalyst pellet developed by Jang et al was charged into the KARI thruster.…”

“…It is difficult to collect detailed data during actual thruster operation, so well-validated simulation codes are required to determine what happens inside a thruster system. Kesten studied a numerical simulation model during development of the Shell 405 catalyst. He suggested that the gas-phase and solid-phase governing equations indicated that the reaction chamber could be viewed as one-dimensional porous medium.…”

“…As a consequence, they simulated various cases according to thruster size, bed loading, and chamber inlet pressure, and also utilized the results of their numerical analyses to design a 10 N thruster . Makled and Belal compared the ammonia dissociation fraction and gas temperature inside the catalyst bed using the correlation equation of Kesten and a two-step chemical reaction calculation. Han et al conducted a hot-firing test using a hydrazine thruster developed by the Korea Aerospace Research Institute (KARI) and tabulated the measured chamber temperature, pressure, and propellant mass flow rate.…”