Performance analysis of the combined supercritical CO2 recompression and regenerative cycle used in waste heat recovery of marine gas turbine

With the aim to recover the marine gas turbine exhaust heat, and improve the ship part-load thermal efficiency, a combined cycle coupling supercritical CO2 recompression and regenerative cycle is proposed. The proposed system adopts modular design. The application process can choose the module according to the ship's need. The cycle parameters, including the output power, exergy efficiency, the heat exchanger area per unit power output (APR) and the levelized energy cost (LEC), have been analyzed and optimized. The multi-objective optimization method based on genetic algorithm is selected as the optimization method to obtain the optimum system parameter. From the viewpoints of the output power, compactness and economics, the obtained result reveals the superiority of the proposed cycle compared to the common supercritical CO2 recompression cycle, the common supercritical CO2 regenerative cycle and the combined cycle coupling two supercritical CO2 regenerative cycle. What's more, the proposed system can effectively improve the part-load performance of the ship. When the gas turbine fails, the combined cycle could meet 80% propulsion power of the ship by enabling the second combustion chamber, which could be used as the backup generator and improve the safety of the ship operation. The proposed cycle is suitable for marine gas turbine waste heat recovery, it has advantages of deep utilization of waste heat, high compactness and low cost.