Feasibility assessment of a CO2 based power, cooling, and heating system driven by exhaust gas from ocean-going fishing vessel

The research presents a novel CO2 transcritical trigeneration system for ocean-going fishing vessel. Cascade ejectors are employed to decrease the exergy destruction caused by the dual evaporators, enhancing the cooling capacity of the system. By recovering the waste heat of exhaust, the system is designed to cover refrigeration demand of a refrigerated sea water (RSW) tank, the domestic hot water demand at different temperature levels onboard, as well as the power for sailing. The performance of the system is investigated from both thermody-namic and economic perspectives. The feasibility of applying the proposed system to replace the original refrigeration system of a RSW tank is evaluated in different periods, including prechilling, chilling, and chilling maintenance. Analysis show that sufficient cooling can be provided to a RSW tank under most typical engine operation modes, which is significantly influenced by the split ratio and refrigeration capacity ratio. Constraint multi-objective genetic algorithm under engine load of 100% is conducted to determine the maximum potential of the system under the optimum working condition and ensure the smooth operation of the system under all typical engine load. It is estimated that a cooling capacity of 619.9 kW can be offered to the RSW, and the cooling provided to the cold room (502.8 kW) can realize the freezing of 25018 kg fish. After covering the power consumed by compressor and pump, the system still can reach a net power output of 97.32 kW. The thermal efficiency of the engine integrated with the proposed system is improved by 2.89%, and the brake specific fuel consumption is reduced by 5.88%. And the heat rejected by the system can be used to heat water from 25 degrees C to 45 degrees C (11.93 kg/s) and 90 degrees C (2.18 kg/s), respectively. The proposed system shows better overall performance compared to the basic system without ejectors.