The D2-Law of Droplet Evaporation When Calculating the Droplet Evaporation Process of Liquid Containing Solid State Catalyst Particles

The review presents the D2-law of droplet evaporation, which is used to describe the spraying process involving the evaporation of droplets. This law, the subject of numerous publications, can be successfully applied to describe the droplet evaporation process under various conditions, including the calculations of the process of feeding the boiler with a liquid that contains catalyst particles. To date, not a lot of work has been devoted to this issue. The paper is a continuation of previous research concerning the spraying of liquids with a catalyst, which improves the efficiency of the process. The conducted analysis showed that the experimental data from previously published work are very compatible with the data obtained from the D2-law of droplet evaporation. At the standard speed of about 20 m/s of an aerosol flowing through a dust duct, droplets in the stream should be observed up to a distance of 1 m from the outlet of the apparatus supplying the system. Under such flow conditions, a droplet’s lifetime must be above 0.05 s. The dependence between a droplet’s lifetime and its diameter and temperature was determined. The obtained results confirmed that the effective droplet diameter is above 30 µm. Such droplets must be generated and then fed to the boiler for the catalyst to work properly. This law is an engineering approach to the problem, which uses relatively simple model equations in order to determine the evaporation time of a droplet

Coal Char Kinetics of Oxidation and Gasification Reactions

Experimental investigations and numerical simulations have been conducted in this study to derive and test the values of kinetic parameters describing oxidation and gasification reactions between char carbon and O2 and CO2 occurring at standard air and oxy-fuel combustion conditions. Experiments were carried out in an electrically heated drop-tube at heating rates comparable to fullscale pulverized fuel combustion chambers. Values of the kinetic parameters, obtained by minimization of the difference between the experimental and modeled values of char burnout, have been derived and CFD simulations reproducing the experimental conditions of the drop tube furnace confirmed proper agreement between numerical and experimental char burnout

Numerical and experimental investigations into combustion of a single biomass particle

This paper presents numerical and experimental investigations of combustion of a single biomass particle. The Implicit Continuous-fluid Eulerian (ICE) method combined with particle mass and energy conservation equations was used for an unsteady 1-dimensional numerical simulation of single biomass particle combustion. The single biomass particle was treated as a Lagrange discrete particle which served as a supplementary boundary condition of a permeable rigid wall which makes possible the flow of gas species into or out the computational domain. The mass fluxes of individual gas species describing devolatilization and biomass char combustion and particle temperature being the solution of the particle mass and energy conservation equations were applied to define the boundary conditions in the ICE method which describes a multispecies chemically reactive unsteady compressible flow around the particle. To define the gas velocity and density, the unsteady mass and momentum equations have been combined each other like usually made in projection methods to get the Helmholtz equation which together with appropriate boundary conditions define gas pressure. Considering the spherical symmetry of the system assumed for the numerical simulation, the time-dependent 1-dimensional energy and species mass conservation equations and the pressure Helmholtz equation can be efficiently solved by use of the tridiagonal matrix algorithm (TDMA). The combustion process has been also experimentally investigated in an electrically heated up reactor through which the flow of hot gases up to temperature of 1223 K is possible. Heating up, devolatilization, ignition and combustion of volatiles in a laminar diffusion flame around the particle and biomass char combustion are phenomena which occurred and have been recorded by a high speed camera during the whole combustion process. The particle temperature has been measured by a thermocouple on which the particle was placed. Experimental investigations of combustion have been performed for the single willow particle having the diameter around 1 mm burning in air at temperature of 923 K. Numerical results have been compared with the experimental ones. The numerical results, i.e. the particle temperature, gas species concentrations and other, correctly reflect the whole combustion process experimentally observed

N -annulated perylene as an efficient electron donor for porphyrin-based dyes: Enhanced light-harvesting ability and high-efficiency Co(II/III)-based dye-sensitized solar cells

10.1021/ja409291gJournal of the American Chemical Society1361265-272JACS