The paper discusses the possibility of applying the trigeneration energy concept (cogeneration + absorption cooling) on diesel-powered refrigerated ships, based on systematic analyses of variable energy loads during the estimated life of the ship on a predefined navigation route. From a methodological point of view, mathematical modeling of predictable energy interactions of a ship with a realistic environment yields corresponding models of simultaneously occurring energy loads (propulsion, electrical and thermal), as well as the preferred trigenerational thermal effect (cooling and heating). Special emphasis is placed on the assessment of the upcoming total heat loads (refrigeration and heating) in live cargo air conditioning systems (unfrozen fruits and vegetables) as in ship accommodations. The obtained results indicate beneficiary energy, economic and environmental effects of the application of diesel engine trigeneration systems on ships intended for cargo transport whose storage temperatures range from −25 to 15 °C. Further analysis of trigeneration system application to the passenger ship air conditioning system indicates even greater achievable savings.

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Added resistance in waves is one of the main causes of an increase in required power when a ship operates in actual service conditions. The assessment of added resistance in waves is important from both an economic and environmental point of view, owing to increasingly stringent rules set by the International Maritime Organization (IMO) with the aim to reduce CO2 emission by ships. For that reason, it is desirable to evaluate the added resistance in waves already in the preliminary ship design stage both in regular and irregular waves. Ships are traditionally designed and optimized with respect to calm water conditions. Within this research, the effect of prismatic coefficient, longitudinal position of the centre of buoyancy, trim, pitch radius of gyration, and ship speed on added resistance is investigated for the KCS (Kriso Container Ship) container ship in regular head waves and for different sea states. The calculations are performed using the 3D panel method based on Kelvin type Green function. The results for short waves are corrected to adequately take into account the diffraction component. The obtained results provide an insight into the effect of variation of ship characteristics on added resistance in waves.

One of the short-term operational measures for fuel savings and reducing CO2 emissions from ships at sea is sailing at reduced speed, i.e., slow steaming, while the gasification of the ship represents an important mid-term technical measure. In this study, the energetic and ecological benefits of slow steaming and gasification are studied for a container ship sailing between Shanghai and Hamburg. Resistance and propulsion characteristics in calm water are calculated using computational fluid dynamics based on the viscous flow theory for a full-scale ship, while the added resistance in waves is calculated by applying potential flow theory. The propeller operating point is determined for the design and slow steaming speeds at sea states with the highest probability of occurrence through the investigated sailing route. Thereafter, the fuel consumption and CO2 emissions are calculated for a selected dual fuel engine in fuel oil- and gas-supplying modes complying with IMO Tier II and Tier III requirements. The results demonstrate a significant reduction in fuel consumption and CO2 emissions for various slow steaming speeds compared to the design speed at different sea states, and for the gasification of a container ship. For realistic weather conditions through the investigated route, the potential reduction in CO2 emissions per year could be up to 11.66 kt/year for fuel oil mode and 8.53 kt/year for gas-operating mode. CO2 emission reduction per year due to gasification under realistic weather conditions could be up to 22 kt/year.

The paper presents steam turbine power, energy and exergy efficiencies and losses analysis during steam extractions opening/closing. The analyzed steam turbine can be used in steam power plant or in the marine steam propulsion system (low-power steam turbine). Steam extractions opening and closing can have a notable influence on various turbine operating parameters, what is currently purely exploited in the literature. Turbine developed power during steam extractions opening/closing is direct proportional to turbine energy and exergy losses and reverse proportional to turbine exergy efficiencies. Turbine energy efficiency is not affected by steam extractions opening/closing. Considering all the combinations of turbine steam extractions opening/closing, it is obtained that the range of real developed power is between 30612.91 kW and 34289.14 kW, while the range of turbine exergy efficiencies is between 85.65% and 86.08%. The range of turbine energy power losses in all possible observed combinations is between 5401.78 kW and 6050.30 kW, while the range of exergy destruction is between 4949.44 kW and 5746.81 kW.

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