TOPSIS and genetic algorithm-based optimization of a marine multi-generation system with 3E evaluation

Today, the growth of energy consumption and global warming necessitate reducing the use of fossil fuels and increasing energy productivity more than ever. Renewable energies are among the approaches toward less fossil fuel consumption. However, in some specific cases, like ships, renewable energies may be much more difficult to implement. This study suggests a multigeneration system for producing power, cooling, heating, hydrogen, oxygen, desalinated water, and consumed hot water in a ship. The system includes a desalinator, an electrolyzer, a supercritical CO2 (SCO2) power cycle, a transcritical CO2 refrigeration cycle, and a hydrogen engine. The exhaust heat of the ship supplies the required energy of the system. Energy, exergy, and exergoeconomic equations are applied to analyze this system, and two multi-objective optimization methods, i.e., genetic and TOPSIS, are employed to optimize the influential parameters in the system, e.g., evaporator temperature, turbine inlet temperature, turbine inlet pressure, pressure effect of the desalinator, salinity of the seawater inflow, and flow rate of the consumed hot water. Exergy and energy efficiency and total cost rate constitute the objective functions that are finally obtained at 47.55 %, 21.36 %, and 33.914 $/h at the optimal point. Then, the maximum values of the exergy destruction, cost rate, and exergoeconomic factor are found to be equal to 5493 kW, 10.74 $/h, and 82.18 % for the generator, cooling-cycle compressor, and pump, respectively. Lastly, the exergoeconomic analysis reveales that the maximum cost rate belongs to the power-cycle generator and is equal to 717.5 $/h.