New: Defense of M.Sc. thesis:
The thesis defense by Mr. Farshid Masihizadeh, a M.Sc. candidate in aerospace engineering, entitled "Modeling of Evaporation and Thermal Decomposition of a Hydrogen Peroxide Droplet", will be held on 27-Jul-2026 at 14:00 (Tehran time) at the School of Mechanical Engineering of Iran University of Science and Technology (IUST). The members of the Space Propulsion Research Laboratory (SPRL) invite all interested parties in this field and the other relevant areas to participate in this defense.
Abstract
In this research, a coupled numerical model has been developed to investigate the simultaneous process of single droplet evaporation and thermal decomposition of pure hydrogen peroxide (H₂O₂) vapor in a quiescent environment. A pure H₂O₂ droplet is considered in a hot, quiescent gaseous environment, and the conservation equations of mass, energy, and chemical species are solved in coupled form in the liquid and gas phases using a finite volume approach.
One of the main challenges of this research was determining appropriate kinetic coefficients for the single-step decomposition reaction of H₂O₂. For this purpose, the detailed decomposition kinetics of H₂O₂ were first solved using the Cantera library over a wide temperature range, and the resulting data were then converted to a single-step Arrhenius model through curve fitting. The pre-exponential factor A and activation energy E_a were extracted from this process and employed in the numerical model.
Given the lack of experimental data for H₂O₂ droplet evaporation and decomposition, model validation was carried out in two stages: first against evaporation and combustion data of normal heptane (n-C₇H₁₆) droplets as a reference hydrocarbon fuel, and then against ethanol (C₂H₅OH) droplet data due to the polar nature of this compound, which makes it closer to H₂O₂ in this regard.
The central question of this research was whether the thermal decomposition of H₂O₂ vapor can occur simultaneously with droplet evaporation and affect the evaporation rate and droplet lifetime. The results of this thesis show that this effect is real and direct: H₂O₂ vapors decompose within the boundary layer surrounding the droplet, and the released heat alters the temperature gradient around the droplet compared to the pure evaporation case. This change in the temperature gradient in turn affects the evaporation rate and droplet lifetime. Therefore, the mechanism by which decomposition influences evaporation is not merely delayed and mediated through an increase in ambient temperature, but rather through the direct modification of the temperature field in the droplet boundary layer simultaneously with evaporation.
A parametric analysis of the effect of ambient temperature and initial droplet diameter on the transient behavior of the system was conducted, and the results are presented in the relevant chapter. The findings of this research can be applied to the design and optimization of H₂O₂-based microthruster systems.

Keywords
Hydrogen peroxide, thermal decomposition, droplet evaporation, numerical modeling, droplet lifetime