The homogeneous (gas-phase) and heterogeneous (catalytic) ignition of fuel-lean premixtures is investigated analytically and numerically in two-dimensional laminar channel-flow configurations with uniform incoming properties and isothermal catalytic walls. First-order matched activation energy asymptotics are employed, along with a one-step catalytic reaction and a one-step large activation ene...

Background: The heterogeneous composition of the human body presents numerous tissue types and cavities with widely differing radiologic properties. The aim of the present work was to develop a low cost homogeneous and heterogeneous phantom and the absorbed dose were measured by ionization chamber for different radiotherapy treatment techniques and compared with treatment planning syst...

Simulations of the evolution of stratospheric distributions of hydrogen chloride (HC1) and hydrogen fluoride (HF) have been carried out for the period of the Airborne Arctic Stratospheric Expedition (AASE) with at three-dimensional chemistry-transport model. Simulations were performed assuming only homogeneous gas phase &enr. istry for HF and both homogeneous gas phase and heterogeneous chemist...

Liquid/gas flows are experimentally investigated in 200 and 525 mm square microchannels made of glass and silicon. Liquid and gas are mixed in a cross-shaped section in a way to produce steady and homogeneous flows of monodisperse bubbles. Two-phase flow map and transition lines between flow regimes are examined. Bubble velocity and slip ratio between liquid and gas are measured. Flow patterns ...

Experiments have been conducted to study the controlling mechanisms involved in the transition from smoldering to flaming of a porous combustible material, flexible polyurethane foam, with an air flow forced across one of the porous-fuel surfaces. The experiments are performed in a small-scale, vertical, combustion wind tunnel, with the air flow forced upward and parallel to an exposed foam sur...

In this study, the homogeneity of the continuum model of a fixed bed reactor operated in steady state and unsteady state systems for lean CH4 oxidation is investigated. The steady-state fixed bed reactor system was operated under once-through direction, while the unsteady-state fixed bed reactor system was operated under flow reversal. The governing equations consisting of mass and energy balan...