## 1 Introduction  
The development of efficient CO\({}_{2}\) abatement systems is widely pursued as a means of mitigating the detrimental effects of global warming [1]. Currently, intense research efforts are focusing on CO\({}_{2}\) capture technologies, such as membrane processes [2], adsorption systems [3], and materials- [4; 5] and solvent-based absorption/desorption processes [6]. The latter represents a technology with significant potential, which has been demonstrated even in large-scale plants [7; 8]. The selection of efficient solvents or mixtures in solvent-based CO\({}_{2}\) capture plays an important role in the process configuration, the regeneration energy requirements, and the process economics [9]. While the development of new solvents has been an active research field, the ones proposed to date have not managed to reduce the regeneration energy requirements by more than 25% compared to the reference monoethanolamine (MEA) solvent, with detrimental effects on the reduction of capture costs [1]. In recent years, a new class of solvents called phase-change solvents [10] has indicated experimentally verified regeneration energy reductions of approximately 43% compared to MEA [11; 12]. Unlike conventional solvents,phase-change solvents undergo a phase separation upon reaction with CO\({}_{2}\) or a change in temperature. The resulting CO\({}_{2}\)-lean phase may be mechanically separated and recycled to the absorber using insignificant amounts of energy, whereas the CO\({}_{2}\)-rich phase is introduced into a desorption process. This reduction in the solvent flow rate that undergoes thermal separation, and in some cases, desorption at lower than 90 \({}^{\circ}\)C [6], enables the corresponding reduction in regeneration energy requirements. The inclusion in the selection procedure of solvents or mixtures that exhibit phase-change behavior upon the absorption of CO\({}_{2}\) within a specific range of temperature enables the utilization of the advantages that this type of solvents bring in the reduction of the overall energy penalty for CO\({}_{2}\) capture. [PERSON] et al. [13] compared phase-change solvent mixtures to conventional solvents based on their performance regarding CO\({}_{2}\) capture using the cyclic solvent capacity, the parasitic electricity losses, and the regeneration energy as criteria. Phase-change solvents showed improved performance in all aspects except the solvent cost due to the small industrial production for such solvents. For this purpose, a short-cut model for the absorption-desorption system has been utilized, initially developed by [PERSON] et al. [14] but extended by [PERSON] et al. [13] to account for phase-change solvents. However, the evaluation of the performance metrics has been accomplished by considering only the optimal design operating point at steady-state operation. Flue gas streams are usually susceptible to variabilities in their conditions, such as the flow rate, composition, concentration, and temperature, due to either production changes (e.g., variable power plant operation, fuel type change, and so forth) or other disturbances affecting the plant. The variability in the flue gas stream affects the operation of the capture plant by deviating the plant's operating conditions from the cost-effective design point with potentially detrimental effects on the achieved process and economic performance. In addition, several other factors may influence the operating efficiency of the capture plant, such as solvent degradation, solvent losses, and heat exchanger inefficiencies. It is therefore imperative to investigate the performance of candidate CO\({}_{2}\) capture solvents and mixtures, not only at the nominal design point but also for a wide range of off-design conditions. To this end, the use of a control system is indispensable for addressing variability but the selection of an appropriate solvent can greatly facilitate and enhance the performance of such a control system.