Evaluation and optimization of an engine waste heat assisted Carnot battery system for ocean-going vessels during harbor stays

Abstract

The pollution and environmental damage caused by ship emissions during docking is an urgent issues that needs to be addressed. In this study, a jacket water waste heat Carnot battery (JCB) system is designed as an energy storage device to recover the water waste heat of the ship's main engine cylinder liner and as a power output device when the main engine stops in port. The JCB system is evaluated and optimized from the perspectives of thermodynamics, exergy, and cost, with a focus on the performance under different working fluid combinations. The results show that improving the efficiency of the compressor, turbine, and recuperator can significantly enhance the system's performance, with the compressor and turbine being the most expensive components. The heat exchanger has the highest exergy destruction, accounting for almost half of the total system. In the multi-objective optimization of different working fluid combinations, R365mfc/R365mfc is found to be the best choice, with the power-to-power efficiency of the system reaching 110.15 % and the 5-year levelized cost of storage (LCOS) being 0.139 $/kWh. A case study of the actual route shows that the JCB system designed in this paper can meet the power demand of 100 %, 35.5 %, 61.91 %, and 56.9 % in the four segments during harbor stays. The JCB system proposed in this study provides a new solution for the reduction of emissions and environmental protection during the docking of ships.