sCO 2 capture and storage (CCS) technologies play a significant role in greenhouse gas (GHG) control. In our previous work, a novel cryogenic CO 2 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 (X 1 : 1 ~ 3 L/min), temperature of FPSC-1 (X 2 : -30 ~ -10 °C) and idle operating time (X 3 : 3 ~ 5 h). The objective of this work is to ascertain the optimal performance of the system (with maximum CO 2 recovery, CO 2 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 % CO 2 with 0.52 MJ/kg captured CO 2 input electricity. Meanwhile, the CO 2 productivity is 44.37 kg CO 2 /h.
Nomenclature
X1Flow rate of flue gas, L/min X2 Temperature of FPSC-1, °C X3 Idle operating time, h η CO 2 recovery φ CO 2 productivity Abbreviations ANOVA Analysis of variance CCD Central composite design CCS CO 2 capture and storage CFZ Controlled freeze zone EC Energy consumption FPSC Free piston Stirling cooler GHG Greenhouse gas RSM Response surface methodology TPSA Temperature pressure swing adsorption 4