Partial enumeration (PE) is presented as a method for treating large, linear model predictive control applications that are out of reach with available MPC methods. PE uses both a table storage method and online optimization to achieve this goal. Versions of PE are shown to be closed-loop stable. PE is applied to an industrial example with more than 250 states, 30 inputs, and a 25-sample control horizon. The performance is less than 0.01% suboptimal, with average speedup factors in the range of 80-220, and worst case speedups in the range of 4.9-39.2, compared to an existing MPC method. Small tables with only 25-200 entries were used to obtain this performance, while full enumeration is intractable for this example.
Lithium zirconate (Li 2 ZrO 3 ) is one of the most promising materials for CO 2 separation from flue gas at high temperature. This material is known to be able to adsorb a large amount of CO 2 around 500-600 °C. It was also reported that the addition of lithium/potassium carbonate to Li 2 ZrO 3 increased the CO 2 sorption rate when compared to pure Li 2 ZrO 3 . In this study, we examine the CO 2 sorption mechanism on Li 2 ZrO 3 by analyzing phase and microstructure changes of Li 2 ZrO 3 during the CO 2 sorption process with the help of thermogravimetric analysis, scanning electron microscopy, and X-ray diffraction analyses. We report on CO 2 sorption experiments for different Li 2 ZrO 3 based sorbents at different operating conditions in order to identify the most appropriate sorbent and experimental conditions. We also propose a kinetic model that is a variant of a double-shell model proposed in the literature by introducing additional dynamics to obtain a consistent response of the CO 2 uptake curve during the initial part of the sorption process. The proposed model, which has two temperature-dependent parameters that can be adjusted by regression on experimental data, shows excellent capabilities for describing the CO 2 uptake on a Li 2 ZrO 3 based sorbent.
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