Optimization of a novel cryogenic CO2 capture process by response surface methodology (RSM)

CO2 capture and storage (CCS) technologies play a significant role in greenhouse gas (GHG) control. In our previous work, a novel cryogenic CO2 capture process based on free piston Stirling coolers (FPSCs) was developed. In order to improve capture efficiency, the exploited system was optimized using response surface methodology (RSM). The influence of capture conditions on performance was investigated based on three levels and variables and in central composite design (CCD). The parameters contain flow rate (X1: 1-3 L/min), temperature of FPSC-1 (X2: −30 to 10 °C) and idle operating time (X3: 3-5 h). The objective of this work is to ascertain the optimal performance of the system (with maximum CO2 recovery, CO2 productivity and minimum energy consumption). The experimental data was fitted to a second-order polynomial equation using multiple regression analysis and analyzed using analysis of variance (ANOVA). The dimensional response surface plots and the contour plots derived from the mathematical models were utilized to determine optimum conditions. Results indicate the optimum conditions were: flow rate of 2.16 L/min, temperature of FPSC-1 of −18 °C and operating time of 3.9 h. Under these conditions, the whole process can capture 95.20% CO2 with 0.52 MJ/kgcaptured CO2 input electricity. Meanwhile, the CO2 productivity is 44.37 kg CO2/h.