• MACHINES

    EXERGY ANALYSIS OF TWO WATER PUMPS FROM STEAM POWER PLANT AT FOUR DIFFERENT LOADS

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 6, pg(s) 248-251

    Paper presents exergy efficiency and loss analysis of condensate extraction pump (CEP) and main boiler feed pump (BFP) from a conventional steam power plant. Based on the required measured operating parameters at four different loads, it was observed that an increase in driving power for both pumps follows an increase in power plant cumulative developed power. Both analyzed pumps do not have the highest exergy losses at the highest observed load, as can be usually expected. Main boiler feed pump has the highest exergy efficiency, which is equal to 87.00%, at power plant nominal load, while the highest exergy efficiency of condensate extraction pump (95.77%) was observed at 60% of power plant nominal load. The influence of the ambient temperature on both pumps exergy efficiencies and losses is almost negligible.

  • NUMERICAL ANALYSIS OF IN-CYLINDER PRESSURE AND TEMPERATURE CHANGE FOR NATURALLY ASPIRATED AND UPGRADED GASOLINE ENGINE

    Trans Motauto World, Vol. 4 (2019), Issue 2, pg(s) 83-86

    The paper presents numerical analysis of in-cylinder pressure and temperature change for naturally aspirated gasoline engine and two of its upgrades – upgrade with turbocharger only and upgrade with turbocharger along with air cooler. Numerical analysis was performed with 0D (zero-dimensional) numerical model. In-cylinder temperatures, for each engine rotational speed, are the highest for engine upgraded only with the turbocharger. The highest observed in-cylinder temperature of turbocharged engine was obtained at 5000 rpm and amounts 2542.4 °C. In-cylinder pressures are the highest for engine upgraded with turbocharger and air cooler for all rotational speeds except the highest one. The highest observed in-cylinder pressure of a turbocharged engine with air cooler was obtained at 5000 rpm and amounts 129.7 bars. Presented analysis showed that the selected air cooler can be improved at highest engine rotational speed.

  • EXERGY ANALYSIS OF STEAM TURBINE GOVERNING VALVE FROM A SUPER CRITICAL THERMAL POWER PLANT

    Science. Business. Society., Vol. 4 (2019), Issue 4, pg(s) 120-123

    Exergy analysis of steam turbine governing valve from a super critical thermal power plant is presented in this paper. Governing valve was analyzed not only at the highest, but also on two partial steam system loads. The lowest valve exergy destruction is 3598 kW and is obtained at the highest steam system load, while at partial loads of 80% and 60% valve exergy destruction is 13550 kW and 21360 kW. Valve exergy efficiency increases with an increase in system load, from 95.58% at 60% of load to 97.87% at 80% of load. At the highest load, valve exergy efficiency is the highest and is 99.57%. Change in valve steam specific entropy increment (difference in steam specific entropy between valve outlet and inlet) can be used as a tool for quick assessment of valve losses change. The ambient temperature influence on governing valve exergy analysis is low, especially in the highest steam system load where the majority of valve operation can be expected.

  • EXERGY ANALYSIS OF LOW-PRESSURE CONDENSATE HEATING SYSTEM FROM COGENERATION POWER PLANT

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 5, pg(s) 202-205

    The paper presents an exergy analysis of condensate low-pressure heating system of a cogeneration power plant, which consists of one heater, one condensate pump and one pressure reduction valve. The entire system is investigated at three different plant loads. Regardless of the plant load, the highest exergy destruction is noted for the condensate heater (between 416.41 kW and 771.46 kW), after which follows pressure reduction valve with exergy destruction between 57.43 kW and 120.61 kW. Exergy destruction of condensate pump is almost negligible at any plant load and therefore condensate pump has the highest exergy efficiency (between 75.86 % and 77.08 %). Exergy efficiency of condensate heater is between 56.13 % and 59.29 %, while pressure reduction valve has the lowest exergy efficiency of all three analyzed system components and is between 36.98 % and 48.42 %.

  • THE AMBIENT TEMPERATURE INFLUENCE ON DEAERATOR EXERGY EFFICIENCY AND EXERGY LOSSES

    Industry 4.0, Vol. 4 (2019), Issue 4, pg(s) 183-186

    The exergy analysis of deaerator at three different steam power plant loads is performed in this paper. Also, the influence of the ambient temperature change on deaerator exergy efficiency and losses is analyzed. From the exergy viewpoint, deaerator operation shows the best characteristics at middle and high power plant loads. The lowest deaerator exergy destruction of 363.94 kW and the highest exergy efficiency of 93.27 % will be obtained at middle power plant load and at the ambient temperature of 5 °C. The highest deaerator exergy destruction of 1349.99 kW and the lowest exergy efficiency of 81.83 % will be obtained at low power plant load and at the ambient temperature of 45 °C. Deaerator operation is preferable at the lowest possible ambient temperature, regardless of the current power plant load.

  • EXERGY ANALYSIS OF WET COOLING TOWER AT VARIOUS LOADS AND AMBIENT TEMPERATURES

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 4, pg(s) 162-165

    This paper presents an exergy analysis of wet cooling tower at three different loads and in a range of the ambient temperatures.
    Increase in cooling tower load increases its exergy destruction and simultaneously decreases cooling tower exergy efficiency, while an
    increase in the ambient temperature causes a decrease in cooling tower exergy destruction and simultaneously decreases its exergy
    efficiency. The lowest cooling tower exergy destructions (between 1417.54 kW and 2925.65 kW) are obtained at low load. The highest
    cooling tower exergy efficiencies are calculated at the lowest observed ambient temperature of 5 °C – they amount 64.31 % at low load,
    54.80 % at middle load and 53.94 % at high load. The change in ambient temperature for 5 °C resulted with a change in cooling tower
    exergy efficiency of 4 % or more on average.

  • INFLUENCE OF THE AMBIENT TEMPERATURE CHANGE ON STEAM PRESSURE REDUCTION VALVE EXERGY DESTRUCTION AND EXERGY EFFICIENCY

    Trans Motauto World, Vol. 4 (2019), Issue 1, pg(s) 12-15

    The paper presents an exergy analysis of pressure reduction valve mounted in the steam propulsion system on conventional LNG carrier. From exploitation are obtained that the valve pressure and temperature decrease become as higher as steam system load increases. Valve exergy power input and output decreases during the increase in steam system load, mostly because of the steam mass flow decrease. Steam system load increase in exploitation also causes a decrease in valve exergy destruction with a simultaneous decrease in valve exergy efficiency (from 68.42 % to 68.09 %). The ambient temperature variation showed that the valve exergy destruction is the lowest for the lowest observed ambient temperature, in any steam system load. The exergy efficiency of the pressure reduction valve is reverse proportional to valve exergy destruction. An increase in the ambient temperature for 10 °C causes a decrease in analyzed valve exergy efficiency for between 2.5 % and 3 %.

  • AIR COOLING INFLUENCE ON THE PERFORMANCE AND CHARACTERISTICS OF TURBOCHARGED DIRECT INJECTION GASOLINE ENGINE

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 3, pg(s) 104-107

    The paper presents numerical analysis of air after turbocharger cooling process and its influences on the gasoline engine operating parameters. Analysis was performed with numerical 0D (zero-dimensional) simulation model by using two sets of simulations – for gasoline turbocharged engine without air cooler and for the same engine with air cooler included. Between engine rotational speeds of 1000 rpm and 5000 rpm, air cooling process increases analyzed engine developed power and engine torque up to 20.67%, increases cylinder maximum pressure up to 17.03%, increases engine volumetric efficiency up to 23.65% and reduces brake specific fuel consumption up to 1.32% when compared with the same engine without air cooler. At the highest engine rotational speeds (between 5000 rpm and 6000 rpm) it was observed that selected air cooler does not offer the required and expected performance, so air cooling process in this engine operating area can and should be improved.

  • NUMERICAL ANALYSIS OF REAL OPEN CYCLE GAS TURBINE

    Science. Business. Society., Vol. 4 (2019), Issue 1, pg(s) 11-14

    The paper presents a thermodynamic analysis of gas turbine with real open cycle. Gas turbine operates in combined heat and power (CHP) system. Analysis is provided by using measured operating parameters of operating mediums (air and combustion gases) in all required operating points. Cumulative real turbine developed power amounts 78611.63 kW. In the whole gas turbine process, the highest losses occur in combustion chambers during the heat supply process and amounts 13689.24 kW. Turbine power losses are equal to 7976.22 kW, while the turbo-compressor power losses amounts 4774.24 kW. While taking into account all analyzed gas turbine components, the highest efficiency of 90.79% has turbine, followed by combustion chambers which efficiency is equal to 89.01%. Turbo-compressor efficiency amounts 88.59% and the whole gas turbine cycle has efficiency equal to 33.15%.

  • NUMERICAL ANALYSIS OF REAL OPEN CYCLE GAS TURBINE

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 2, pg(s) 70-73

    The paper presents a thermodynamic analysis of gas turbine with real open cycle. Gas turbine operates in combined heat and power (CHP) system. Analysis is provided by using measured operating parameters of operating mediums (air and combustion gases) in all required operating points. Cumulative real turbine developed power amounts 78611.63 kW. In the whole gas turbine process, the highest losses occur in combustion chambers during the heat supply process and amounts 13689.24 kW. Turbine power losses are equal to 7976.22 kW, while the turbo-compressor power losses amounts 4774.24 kW. While taking into account all analyzed gas turbine components, the highest efficiency of 90.79% has turbine, followed by combustion chambers which efficiency is equal to 89.01%. Turbo-compressor efficiency amounts 88.59% and the whole gas turbine cycle has efficiency equal to 33.15%.

  • NUMERICAL ANALYSIS OF TURBO-GENERATOR STEAM TURBINE ENERGY EFFICIENCY AND ENERGY POWER LOSSES CHANGE DURING THE VARIATION IN DEVELOPED POWER

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 1, pg(s) 11-14

    Developed power variation of turbo-generator (TG) steam turbine allows insight into the change of turbine energy efficiency and energy power losses. Measurements were performed in five different TG steam turbine operating points and analysis is presented in three randomly selected operating points. Turbine developed power was varied from 500 kW until the maximum power of 3850 kW in steps of 100 kW. Turbine energy efficiency increases from 500 kW to 2700 kW and maximum energy efficiency was obtained at 70.13 % of maximum turbine power (at 2700 kW) in each operating point. From 2700 kW until the maximum of 3850 kW, TG turbine energy efficiency decreases. Change in TG turbine energy efficiency is caused by an uneven intensity of increase in turbine power and steam mass flow. For all observed operating points, energy efficiency during turbine exploitation is approximately 10 % or more lower than the maximum obtained one. A continuous increase in turbine energy power losses during the developed turbine power increase are the most influenced by the continuous increase in steam mass flow through the turbine.

  • GAS TURBINE UPGRADE WITH HEAT REGENERATOR – NUMERICAL ANALYSIS OF ADVANTAGES AND DISADVANTAGES

    Machines. Technologies. Materials., Vol. 12 (2018), Issue 11, pg(s) 346-439

    The paper presents analysis of industrial gas turbine and its upgrade with heat regenerator. Based on a gas turbine operational data from a thermal power plant (base process) it was investigated advantages and disadvantages of heat regenerator implementation in the gas turbine process. Regenerator efficiencies were varied between 75% and 95%. Heat regenerator causes decrease of gas turbine fuel consumption up to 0.621 kg/s with a simultaneous increase in gas turbine process efficiency up to 10.52%. The main disadvantages of heat regenerator implementation are decrease in turbine cumulative and useful power along with decrease in the cumulative amount of heat released from the process.