Modeling of waste heat powered energy system for container ships

• A waste heat powered absorption-compression system is proposed for container ship cooling, refrigeration and heating.
• A detailed model is developed and validated against experimental data.
• The system is investigated with a focus on fuel consumption and CO2 emission reductions.
• Payload and life cycle cost analysis are conducted.

A novel waste heat powered system is proposed to meet heating, cooling and refrigeration demands on a container ship to reduce its fuel consumption. A cascaded absorption-compression configuration is adopted to meet cooling and refrigeration demands simultaneously. Major components such as sea route weather, vapor compression cycle reefer units and main engine are modeled in details. The system is simulated under transient sea route weather conditions and loading/unloading conditions, and compared with the conventional system design. The conventional system simulation results are validated against experimental data with coefficient of variation of the root mean square error less than 30%. Simulation results revealed the proposed waste heat powered system is able to reduce diesel generator's fuel consumption by 38% and hot climate are in favor of fuel savings. Sankey diagram is used to analyze energy and CO2 emission flows of both systems. It is concluded that direct emissions from diesel generators are the dominant factor in both systems. Replacing the conventional system with the waste heat powered system has negligible effects on the main engine fuel consumption for propulsion but reduces life cycle cost by 12%.