Modeling the burnout of solid polydisperse fuel under the conditions of external heat transfer

A self-similar burnout mode of solid polydisperse fuel is considered taking into consideration heat transfer between fuel particles, gases, and combustion chamber walls. A polydisperse composition of fuel is taken into account by introducing particle distribution functions by radiuses obtained for the kinetic and diffusion combustion modes. Equations for calculating the temperatures of particles and gases are presented, which are written for particles average with respect to their distribution functions by radiuses taking into account the fuel burnout ratio. The proposed equations take into consideration the influence of fuel composition, air excess factor, and gas recirculation ratio. Calculated graphs depicting the variation of particle and gas temperatures, and the fuel burnout ratio are presented for an anthracite-fired boiler. © 2013 Pleiades Publishing, Inc

Burning of liquid fuel in furnace equipment

The current and initial particle radius distribution functions for the automodel regime of polydisperse liquid fuel droplet system were derived based on the kinetic equation and single droplet evaporation rate. The automodel system parameters and equation for modelling the fraction of currently unevaporated and unburned fuel and ambient temperature change during evaporation of the droplets were obtained.На основе кинетического уравнения и полученной скорости испарения одиночной капли определены текущая и начальная функции распределения частиц по радиусам для автомодельного режима испарения полидисперсной системы капель жидкого топлива. Получены автомодельные параметры системы, уравнение для расчета доли неиспарившегося, а также несгоревшего к текущему моменту времени топлива и изменения температуры среды в процессе испарения капель в инертной среде и их горения в окислительной среде

On the kinetics of combustion spraying liquid fuel drops

На основе кинетического уравнения и полученной скорости горения одиночной капли определены текущая и начальная функции распределении частиц по радиусам для автомодельного режима горения. Скорость горения капли получена для случая кондуктивного подвода теплоты к поверхности капли от фронта горения. Получены выражения для расчета доли несгоревшего к текущему моменту времени топлива и автомодельные параметры, необходимые для расчетов горения полидисперсных систем капель.Based on the kinetic equation and the resulting burning rate determined by a single drop of the current function and the initial distribution of the particle radius for the self-burning mode. Droplet burning rate obtained for the case of conductive heat supply to the drop of the combustion front surface. The expressions to calculate the percentage of unburned fuel to the current point in time and self parameters required for the calculation of combustion systems polydisperse drops

Josephson φ\varphi-junctions based on structures with complex normal/ferromagnet bilayer

We demonstrate that Josephson devices with nontrivial phase difference $0<\varphi_g <\pi$ in the ground state can be realized in structures composed from longitudinally oriented normal metal (N) and ferromagnet (F) films in the weak link region. Oscillatory coupling across F-layer makes the first harmonic in the current-phase relation relatively small, while coupling across N-layer provides negative sign of the second harmonic. To derive quantitative criteria for a $\varphi$-junction, we have solved two-dimensional boundary-value problem in the frame of Usadel equations for overlap and ramp geometries of S-NF-S structures. Our numerical estimates show that $\varphi$-junctions can be fabricated using up-to-date technology.Comment: 14 pages, 9 figure

The effect of normal and insulating layers on 0-πtransitions in Josephson junctions with a ferromagnetic barrier

Using the Usadel approach, we provide a formalism that allows us to calculate the critical current density of 21 different types of Josephson junctions (JJs) with a ferromagnetic (F) barrier and additional insulating (I) or/and normal (N) layers inserted between the F layer and superconducting (S) electrodes. In particular, we obtain that in SFS JJs, even a thin additional N layer between the S layer and F layer may noticeably change the thickness ${d}_{{\rm{F}}}$ of the F layer at which the 0-π transitions occur. For certain values of ${d}_{{\rm{F}}},$ a 0-π transition can even be achieved by changing only the N layer thickness. We use our model to fit experimental data of SIFS and SINFS tunnel junctions