Exergo-Economic and Environmental Analysis of Exhaust Gas Waste Heat Recovery from Marine Diesel Engine Using Organic Rankine Cycle with Different Working Fluids

As a result of global warming and the strict regulations imposed on the maritime industry, efficient ship operation is becoming increasingly important. Organic Rankine Cycle (ORC) systems, suitable for low to medium-temperature heat soruces, are emerging as viable systems for utilizing heat sources. In this study, exergo-economic analysis of exhaust gas recovery from the container ship marine diesel engine load using ORC and its impact on CO2 emissions was conducted. The performance comparison was made for R245fa, R1233zd(E), R1234ze(Z), and cyclopentane. Additionally, the effect of evaporation temperature on system performance was analyzed. The results show that due to its high critical temperature, cyclopentane has 20,9% thermal efficiency and net power output of 2257,84kW, followed by R1233zd(E) with net power output of 1805,2 kW and thermal efficiency of 16,76%. The ship 1381.4 kW navigational electrical load can be met with the ORC, additional gain of 809 kW can also be achieved from the main engine power via the shaft generator. The total system cost with cyclopentane is $60,04/h, calculated as $33,28/h with R1234ze(Z). The EEXI (Energy Efficiency Existing Index) decreased by approximately 9,6%, while the CII (Carbon Intensity Indicator) showed reduction of about 7,5%.