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This work presents a simulation study of several Ca-Cu looping variants with CO2 capture,aiming at both parameter optimization and exergy analysis of these Ca-Cu looping systems.Three kinds of Ca-Cu looping are considered: 1) carbonation-calcination/reduction-oxidation;2) carbonation-oxidation-calcination/reduction and 3) carbonation/oxidation-calcination/reduction.A conventional Ca looping is also simulated for comparison.The influences of the calcination temperature on the mole fractions of CO2 and CaO at the calciner outlet,the CaCO3 flow rate on the carbonator performance and the Cu/Ca ratio on the calciner performance are analyzed.The second kind of Ca-Cu looping has the highest carbonation conversion.At 1 × 105 Pa and 820 ℃,complete decomposition of CaCO3 can be achieved in three Ca-Cu looping systems,while the operation condition of 1 × 105 Pa,840 ℃ is required for the conventional Ca looping system.Furthermore,the Cu/Ca molar ratio of 5.13-5.19 is required for the Ca-Cu looping.Exergy analyses show that the maximum exergy destruction occurs in the caldner for the four modes and the second Ca-Cu looping system (i.e.,carbonation-oxidation-calcination/reduction) performs the highest exergy efficiency,up to 65.04％,which is about 30％ higher than that of the conventional Ca looping.