This thesis consists of two parts discussing modelling of heterogeneous catalytic reactors. In the first one, an industrial prototype of a fluidized bed reactor serving as a hydrogen generator based on endothermic decomposition of formic acid is studied. After initial determination of the main reactor characteristics a system of nine con- stituents is derived and, consequently, reduced to a three phase flow. The solid and bubble particles immersed in a liquid are modelled by the Basset-Boussinesq- Ossen equation. Furthermore, an averaging technique is used to derive a three phase Euler-Euler model. Finally, numerical computations with a verification towards the measurements and a CFD analysis are proceeded. The second part discusses interfacial transport phenomena between a bulk and catalytic surfaces of a reactor mediated via the boundary conditions. The constitu- tive relations, that by construction comply with the second law of thermodynamics, follow from the specification of suitable thermodynamic potentials together with an identification of the bulk and surface entropy productions. The derived model is suitable for further analysis providing clear guidelines for the incorporation of the Langmuir-type adsorption model as well as other sorption models. Keywords: Heterogeneous catalysis, multi-phase...

<p> Understanding the behavior of liquid hydrocarbon propellants under high pressure and temperature conditions is a crucial step towards improving the performance of modern-day combustion engines (liquid rocket engines, diesel engines, gas turbines and so on) and designing the next generation ones. Under such harsh thermodynamic conditions (high P&T) propellent droplets may experience anywhere from sub-to-trans-to-supercritical regime. The focus of this research is to explore the dynamics of the vapor-liquid two phase system formed by a liquid hydrocarbon fuel (n-heptane or n-dodecane) and ambient (nitrogen) over a wide range of P&T leading up to the mixture critical point and beyond. Molecular dynamics (MD) has been used as the primary tool in this research along with other tools like: phase stability calculations based on Gibb’s work, Peng Robinson equation of state, density gradient theory and neural networks.</p>