Next, the performance of the model ABT-538 discussed in more detail. Fig. 7 corresponds to the experiment at 3600 ppm methane and 300 s switching time. These conditions lead to stable operation, but are close to the limit of instability (Fig. 2). The model predicts the oscillations of temperature caused by the periodic change in the flow direction, and the greatest discrepancies are observed in the middle of the bed.
Fig. 7. Validation of the mathematical model for the RFR with integrated adsorption. Evolution of temperature at different catalytic bed positions: experiments () and simulations (). yG0 = 3600 ppm, tsw = 300 s.Figure optionsDownload full-size imageDownload as PowerPoint slide
When decreasing switching time to 100 s, Fig. 8, temperature increases at the beginning of the test due to the accumulation of heat. After some cycles, temperature decreases to the pseudo-steady state value, resulting in stable reactor operation. On the contrary, when the concentration of methane is decreased to 1800 ppm (switching time 300 s), Fig. 9, the reactor is unstable and temperature decreases progressively towards extinction. The model is capable of predicting also the temperature evolution in this unstable experiment.