A novel heat recovery for a marine diesel engine with power and cooling outputs; exergetic, economic, and net present value investigation and multi-criteria NSGA-II optimization

Owing to the marine environmental pollution affected by cruises, the use of techniques to mitigate carbon dioxide emission (CO₂) is vital. Since a quarter of the fuel energy input to the engine is lost, waste management for marine diesel engines can provide some valuable outputs by which the need for other energy conversion-based methods disappears. Hence, the current work proposes a novel model of waste heat recovery for a 1 MW marine diesel engine in a low-temperature framework by which outstanding results are predictable. The defined auxiliary model consists of an absorption power cycle and an ejector refrigeration cycle to produce useful electricity and cooling for air conditioning. This model is designed for the first time and comprehensively analyzed and optimized to set the most suitable state of operation. The potential of the model is measured through the exergy, environmental, economic, and net present value standpoints. Moreover, an advanced evolutionary algorithm based on the non-dominated sorting genetic algorithm-II is applied to reach the optimum cost and exergetic performance. The optimum state showed an exergy efficiency of 35.19 % and products’ specific cost of 53.01 $/GJ. Moreover, the optimum payback period and CO₂ emission reduction equal 6.79 years and 21.5 kg/MWh, respectively.