Adaptation of Radiative Properties of the End Products of Fuels Combustion within the Temperature Range of 1,000…2,000 K

The accuracy of calculating heat exchange by radiation from high-temperature gas flow produced during natural fuels combustion to a large extent depends on the accuracy and status of data on thermophysical properties of gases and the value of the radiative heat flux. The main physical load is carried by the density of the intrinsic heat flux, but all the experimental data on gas mixtures radiation are given as a total emissivity of the components and the mixture in general. That is why this study determines the emissivity factor of carbon dioxide and water vapour as the main constituents of the products of industrial fuel combustion. Dependencies are developed based on reliable experimental data and allowed to perform emissivity factor calculations for the products of combustion. The accuracy of calculated approximation is determined for experimental data in the field of two factors: optical density of gas, and its temperature. The study results are recommended to be usedfor developing heat exchange calculation programs. Keywords: emissivity factor, radiation flux, temperature, carbon dioxide, water vapou

Flame processes from positions of probability theory

To solve the problem of determining the flame temperature in the working space of the thermal units it is proposed to calculate the change of adiabatic enthalpy by using methods of probability theory. It is shown that the normal function of the fuel cells distribution allows to obtain the integral function of enthalpy and adiabatic temperature along the length of flame distribution, including at asymmetrical distribution function. The problem is solved regarding homogeneous diffusive gaseous flames, associated with the combustion of sprayed liquid fuel. Transfer equations solutions regularization’s conditions are defined, homochronic number and Bio mass transfer number relation’s approximations are proposed. For synthesis of the solution on canals of initial forms the corresponding linear connections are proposed; the limits of change of the mass transfer Bio number and the convergence of series sums in the regularization of solutions of the surface combustion equation are defined according to the method of Burke-Schumann. Flame length’s dispersion factor’s variability is considered. The explanation of the S-shaped temperature curve observed by the burning of nearly all fuels in installations of various types is proposed. Flame processes generally examined by probability theory with various density of normal distribution function φ(U) for homogenic flame by normal integral function Ф(U) are described. The steady form Ф(U) significantly explains the S-shaped longitudinal temperature function observed in practice and which serves as a basis for thermal and non-stationary theory of ignition. Actual flame’s temperature determination is possible on flare’s continuum adiabatic temperature placement taking into account the radiative properties of all heat transfer system’s elements. Likewise the task of heterogenic flame’s axial temperature’s description with variable dispersion factor σ can be solved. © 2017, National University of Science and Technology MISIS. All rights reserved