Avaliação e otimização da transferência de calor radiativa em fornalhas corrugadas de geradores vapor fogotubular

Abstract

In this work, the radiative heat transfer was evaluated in corrugated cylindrical surfaces similar the surfaces employed in corrugated furnaces at a fire tube steam generator using the zonal and finite volume methods, with the modeling of corrugated surfaces by cubic spline interpolation. Associated with this study was realized the optimization of these corrugated surfaces using the methodologies of simplex and simulated annealing to determine the optimal configuration of these surfaces for maximum radiative heat transfer. The results indicated that the zonal and finite volume methods, were able to represent the radiative heat transfer in cylindrical and complex literature problems. In terms of the cases studied, the theoretical furnace and the combustion chamber with the changed cylindrical surfaces for corrugated surfaces, the results indicated that the methods of the zonal and of finite volume showed differences in the radiative heat flux to the simulation conditions with large amplitudes, due to absence of modeling the shaded areas of corrugated surfaces in the finite volume method. In the optimization, it was demonstrated that the optimization methodologies found the same solutions to the case study of the theoretical furnace with corrugated surface, highlighting the simplex method for the least amount of evaluations of the objective function. However, for combustion chamber with corrugated surfaces noted that the problem has become ill-posed due to inhomogeneous temperature profile, which led to the simplex method fails to get the optimal point and highlighted non-deterministic characteristics of the simulating annealing method to achieve best results of maximum heat flow. In this context, the simulations show that applying the optimization methodologies is possible to improve radiative heat transfer in the theoretical furnace with corrugated surfaces up to 16.74% and in the combustion chamber surfaces corrugated 7.79%.