Simulation results and discussion

The finite-difference model described above was applied to the oxidation processes of low- and high-Cr steels as discussed in Chapter 5 using diffusion data given as  

5 Main elements of the computer model to simulate the inner oxide scale growth on Cr-containing steels. 

The simulated growth kinetics of the inner oxide scale as a function of the exposure time is shown in Fig. 32.7 for three different grain sizes. In the case of the material with a grain size of d = 10 pm, it could be demonstrated that the simulated data are in excellent agreement with the experimentally determined values of the inner-scale thickness for various exposure times. 

The examples presented above demonstrate the applicability of the combination of the finite-difference technique and computational thermodynamics to complex corrosion processes which depend substantially on the material s microstructure. Of course, much more experimental work is required to describe in detail the variety of possible transport processes, e.g., taking place within the porous inner oxides scale and along the substrate grain boundaries. Strictly speaking, the structure of the interfaces should change as soon as the grain boundaries are covered by an oxide phase which is in contact with the matrix on both sides. Also, the actual value of the grain boundary thickness and its implementation in the finite-difference approach 

6 Simulated lateral concentration profiles of the oxide phases (a) Fe304, (b) FeCr204, and (c) Cr203 formed during exposure of the low-alloy steel B with a grain size of of = 30 pm (X60, Cci = I-44 wt.%) at T = 550°C to air (y = 0 corresponds to the original inner-scale/metal interface at f = 0 s). 

Process systems with significant material recycling 

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The Section is structured as follows. Subsection 2.1 presents a review of the MCFC. Some basic concepts of the gas turbine theory are presented in Subsection 2.2. Subsection 2.3 describes the gas turbine control configm ation. Subsection 2.4 briefly discusses the fuel cell-microturbine hybrid power cycles. Subsection 2.5 outlines the adaptive control. At last. Subsection 2.6 depicts some simulation results and discussion. 

This Section is structured as follows. Subsection 3.1 describes the biomass gasification and Subsection 3.2 outlines the robust control. Finally, Section 3.3 depicts some simulation results and discussion. 

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