Working fluid selection and performance analysis for multistage ship waste heat recovery based on thermal power generation‐organic Rankine cycle combined cycle

The energy utilization rate of ships is low, and waste heat accounts for most of the energy loss of the main engine. In this work, a new method called the thermal power generation‐organic Rankine cycle cascaded cycle is suggested to recover ships waste heat in a cascade utilization way. When comparing the performances of R245fa and R1234ze as working fluids, factors such as performance simulation, environmental protection, and safety were taken into account. Based on these simulation, the organic working fluid chosen is R245fa. On the basis of the cascaded cycle, the influence of working fluid flow rates on essential performance parameters, such as power‐production cost, power output, thermal efficiency, and waste heat utilization of main engine flue gas is explored. The experimental system performs at its best for all metrics when the working fluid flow rates is 0.0403 kg/s, including power output of 483.25 W, thermal efficiency of 8.34%, power‐production cost of 0.3464 $/kWh, and waste heat utilization of main engine flue gas of 69.05%.