No abstract

Energy efficiency has a great importance to reduce both fuel consumption and greenhouse gas emissions, which are the most important focus points for researchers in maritime industry. Exergy analysis, which is widely used to design, analyze and evaluate thermal energy systems, plays an important role to increase energy efficiency. It reveals destruction of available energy in components and leads the researcher to achieve better engineering and systems. Advanced exergy analysis has the capability to reveal the interconnections among system components and improvement potential of inspected components and also the overall system.Steam cycle is used in ships as main or auxiliary power production means for a long time. Also, it is used to recover waste heat from high temperature exhaust gases. Organic rankine cycle (ORC) is an alternative energy recovery strategy to utilize relatively low temperature heat sources to produce power. Usage of ORC in marine power plants is relatively new field to explore.In this paper, a marine power plant with ORC is investigated. Energy and exergy analyses have been carried out to identify conditions and parameters that affect the efficient operation of the system. Then, a parametric study has been conducted to determine the optimum range of operation for power plant and ORC considering different load conditions. Finally, exergy destruction of each component is calculated to give further insight information about the potential of improvement for the efficient operation.

In this paper, superheated and saturated vapor ORCs commonly utilized as waste heat recovery systems of a marine power plant are investigated. First, a parametric study with different organic fluids has been carried out by applying conventional exergy and exergoeconomic analyses to the system considered in order to identify the best possible operating conditions and also to evaluate the findings of conventional exergy-based analyses. Then, advanced exergy and exergoeconomic analyses have been performed on ORCs by splitting exergy destruction rates, exergy destruction costs and investment costs of components and overall system to identify avoidable parts of costs and exergy destructions. Finally, decision criteria were suggested on the selection of more appropriate system depending on the results of the analysis.

No abstract

The efficiency of marine energy systems gain more and more importance considering economic and environmental effects. Additional power is produced by annexation of a supercritical CO2 Rankine cycle (sCO2-RC) via utilization of the exhaust of a marine engine. A parametric study on sCO2-RC is carried out to optimize objective functions such as ECOP, maximum net power output with respect to the outlet temperature of the exhaust stack, and the maximum pressure of the cycle. Then, energy and exergy analyses are applied to the system. Results show that the sCO2-RC system improves thermal efficiency by 8.17% and provides a 7.54% better fuel economy, while exergy efficiency of the sCO2-RC is 51.3% with a net power output of 321.7 kW and ECOP of 1.09. Hence, the results lead to the optimization order of the investigated system components for the improvement in overall efficiency, and the reduction of fuel consumption and environmental effects.