Simulation of Simultaneous Estimation of Gas Temperature and Emissivity in a Furnace by Inverse Analysis in Thermal Radiation.

Resumo

The inverse analysis in thermal radiation problems has many applications in engineering, for example, the prediction of the temperature distribution in furnaces. In direct radiation problems, it is known the radioactive transport equation, the environment features, the boundary conditions and it is important to estimate the field of intensities. By the other hand, in many practical problems, the environment features and the boundary conditions are unknown. In this work,  it is used the conjugate gradient method joint with the discrete ordinated method for simultaneous estimation of gas temperature distribution and wall emissivity. The furnace media is simulated as a combustion gas between two parallel gray surfaces. The gas is considered gray, absorbing, emitting and with isotropic scattering. The inverse problem is formulated as an optimization problem which minimizes the error between the calculated intensity of radiation leaving of the media and a simulated experimental measurement of the intensity of radiation. The inverse analysis consists on the following steps: direct problem; sensibility problem; and the gradient equation. The calculation procedure of each of  these steps is presented and then the algorithm for the solution of the inverse problem is presented. Numerical results to examine the accuracy of the conjugate gradient method for experimental measurements in both cases without and with noise are shown. The results show that the wall emissivities and the temperature distribution of the media can  be estimated with accuracy by the used method.