• MACHINES

    MEAN PRESSURE OF MECHANICAL LOSSES EQUATION FOR MARINE SLOW SPEED TWO-STROKE DIESEL ENGINE

    Machines. Technologies. Materials., Vol. 12 (2018), Issue 2, pg(s) 45-48

    During the engine experimental investigation usually was obtained engine effective power and rotational speed. In order to obtain engine mechanical efficiency and engine indicated power from experimental data, must be used equation for calculation of engine mean pressure of mechanical losses along with its proper coefficients. This equation gives correct values if engine mechanical efficiency and engine indicated power was obtained in the range ±1.5%, when compared with experimentally obtained ones. For marine slow speed twostroke diesel engine 6S50MC MAN B&W was analyzed this equation along with its coefficients during the whole range of engine loads. The mean pressure of mechanical losses equation, when obtained coefficients was applied, gives a percentage difference in the range ±0.79% for the engine mechanical efficiency and percentage difference in the range ±0.85% for the engine indicated power when compared with experimentally obtained values. For the higher engine loads presented equation is even more accurate and precise.

  • MACHINES

    ENERGY EFFICIENCY AND ENERGY POWER LOSSES OF THE TURBOGENERATOR STEAM TURBINE FROM LNG CARRIER PROPULSION SYSTEM

    Machines. Technologies. Materials., Vol. 12 (2018), Issue 1, pg(s) 12-15

    Turbo-generator (TG) steam turbine energy efficiency and energy power losses in a wide range of turbine loads were presented in this analysis. For TG steam turbine was investigated influence of steam specific entropy increment from the real (polytropic) steam expansion on energy power losses and energy efficiency. TG turbine energy power losses, during the all observed loads, were in the range from 646.1 kW to 685.5 kW. The most influenced parameter which defines change in TG turbine energy power losses is steam mass flow change, while for small steam mass flow changes, influence of steam specific entropy increment on steam turbine energy power losses is the most influential. Steam specific entropy incremental change can be used to estimate the change of TG steam turbine energy efficiency. Increase in steam specific entropy increment resulted with a decrease in TG turbine energy efficiency and vice versa. Analyzed steam turbine energy efficiency ranges from 53.84 % to 60.12 %, what is an expected range for low power steam turbines.

  • MACHINES

    MARINE SLOW SPEED TWO-STROKE DIESEL ENGINE – NUMERICAL ANALYSIS OF EFFICIENCIES AND IMPORTANT OPERATING PARAMETERS

    Machines. Technologies. Materials., Vol. 11 (2017), Issue 10, pg(s) 481-484

    This paper presents numerical analysis of efficiencies and non-measured operating parameters for the marine two-stroke slow speed turbocharged diesel engine 6S50MC MAN B&W with direct fuel injection. Numerical analysis was based on a measurement set performed at different engine loads. Calculated efficiencies were mechanical, indicated and effective efficiency, while the calculated important operating parameters were power of engine mechanical losses, mean effective pressure, effective engine torque and specific effective fuel consumption. Engine load was presented in percentage of maximum continuous rating (MCR). The highest engine mechanical efficiency of 94.52 % was obtained at the highest engine load, while the highest engine effective efficiency of 49.34 % was obtained at the engine load 75 % of MCR. Available engine effective torque was from 267380 Nm on the lowest up to 643594 Nm on the highest engine load, while effective fuel consumption was between 171.18 g/kWh and 186.83 g/kWh.