Developed power variation of turbogenerator (TG) steam turbine, which operates at the conventional LNG carrier, allows insight into the change in turbine exergy efficiency and exergy destruction during the increase in turbine power. Measurements of required operating parameters were performed in eight different TG steam turbine operating points during exploitation. Turbine exergy efficiency increases from turbine power of 500 kW up to 2700 kW, and maximum exergy efficiency was obtained at 70.13% of maximum turbine developed power (at 2700 kW) in each operating point. From turbine developed power of 2700 kW until the maximum power of 3850 kW, exergy efficiency decreases. Obtained change in TG turbine exergy efficiency is caused by an uneven intensity of increase in turbine developed power and steam mass flow through the turbine. TG steam turbine exergy destruction change is directly proportional to turbine load and to steam mass flow through the turbine—higher steam mass flow results in a higher turbine load which leads to the higher exergy destruction and vice versa. The higher share of turbine developed power and the lower share of turbine exergy destruction in the TG turbine exergy power inlet lead to higher turbine exergy efficiencies. At each observed operating point, turbine exergy efficiency in exploitation is lower when compared to the maximum obtained one for 8.39% to 12.03%.

Paper has presented an exergy analysis of steam pressure reduction valve, unavoidable element in the steam propulsion plant on LNG carrier. The steam pressure reduction valve was analyzed in a wide range of steam system loads. Along with pressure decrease, through the valve also occur decrease in steam temperature and increase in steam specific entropy. The pressure decrease of the analyzed valve ranges from 4.846 MPa up to 5.027 MPa while the average steam temperature decrease for the whole observed operating range amounts 74.8 °C. At the ambient temperature of 25 °C, valve exergy destruction ranges from 121.72 kW up to 180.64 kW, while exergy efficiency amounts from 80.28 % up to 80.54 %. Variation in the ambient temperature, for the expected engine room temperature range, showed that the exergy destruction of pressure reduction valve increases and exergy efficiency decreases during the increase in the ambient temperature. The lowest average value of pressure reduction valve exergy destruction was obtained at the ambient temperature of 10 °C and amounts 152.03 kW, while at the same ambient temperature was obtained the highest average exergy efficiency of 82.77 %. The highest valve exergy destruction and the lowest exergy efficiency were obtained at the highest observed ambient temperature of 40 °C. Sažetak Članak predstavlja eksergijsku analizu redukcijskog ventila tlaka pare, nezaobilazni element u parnom porivnom postrojenju na LNG brodu. Redukcijski ventil tlaka pare analiziran je u širokom spektru opterećenja porivnog postrojenja. Uz pad tlaka kroz ventil se također događa pad temperature pare i rast u specifičnoj parnoj entropiji. Pad tlaka analiziranog ventila kreće se od 4.846 MP do 5.027 MP dok prosječan pad temperature pare za cijeli promatrani proces iznosi 74.8°C. Kod ambijentalne temperature od 25°C destrukcija eksergije ventila kreće se od 121.72 kW do 180.64 kW dok eksergijska djelotvornost iznosi od 80.28 % do 80.54 %. Varijacija u ambijentalnoj temperaturi za očekivani raspon temperature u strojarnici je pokazala da destrukcija eksergije redukcijskog ventila raste, a eksergijska djelotvornost opada za vrijeme rasta ambijentalne temperature. Najniža prosječna vrijednost destrukcije eksergije redukcijskog ventila dobivena je pri ambijentalnoj temperaturi od 10°C i iznosi 152.03 kW dok je istovremeno na istoj ambijentalnoj temperaturi dobivena najveća prosječna eksergijska djelotvornost od 82.77 %. Najviša destrukcija eksergije ventila i najniža eksergijska djelotvornost dobivene su na najvišoj promatranoj ambijentalnoj temperaturi od 40°C. KEY WORDS pressure reduction valve exergy destruction exergy efficiency ambient temperature KLJUČNE RIJEČI redukcijski ventil tlaka eksergijska destrukcija eksergijska djelotvornost ambijentalna temperatura

The paper presents two components of developed quasi-dimensional numerical model: spray package penetration and gas inflow from the zone without combustion into the spray packages. Correction of spray package penetration along the fuel spray radial axis is presented and described numerically. Numerical model simulation is validated in several measured operating points of direct injection diesel engine, after which the simulation results are presented. According to numerical model settings, each fuel spray was divided into packages (control volumes). In the same time interval, the shortest penetration was obtained for spray packages located at the fuel spray edge. Before reaching the break-up time spray package penetration was linear and after reaching the break-up time, package penetration had a curved form. Later injected spray packages quickly reached and surpassed earlier injected spray packages because earlier injected spray packages hit "gas wall" in the engine cylinder and they were "braked" with surrounding gas in comparison to packages injected later. Gas inflow from the zone without combustion into the spray packages is the most intensive for spray packages positioned at the fuel spray edge. The simulation shows that the inflow mass from the zone without combustion increases for spray packages injected later.

The Automatic identification System (AIS) has been mainly designed to improve safety and efficiency of navigation, environmental protection, coastal traffic monitoring simplifying identification and communication. Additionally, historical AIS data have been used in many other areas of maritime safety, economic and environmental research. The probability of the detection of terrestrial AIS signals from space was presented in 2003, following the advancements in micro satellite technology. Through constant development, research and cooperation between governmental and private sectors, Satellite AIS (S-AIS) has been continuously evolving. Advancements in signal and data processing techniques have resulted in an improved detection over vast areas outside of terrestrial range. Some of the challenges of S-AIS technology include satellite revisit times, message collision and ship detection probability. Data processing latency and lacking the continuous real-time coverage made it less reliable for end user in certain aspects of monitoring and data analysis. Recent developments and improvements by leading S-AIS service providers have reduced latency issues. Complementing with terrestrial AIS and other technologies, near real-time S-AIS can further enhance all areas of the global maritime monitoring domain with emerging possibilities for maritime industry.