numericals of power plant equipments(mechanical part)

power plant equipment(mechanical part)

1.    A single cylinder engine operating at 2000 rpm develops a torque of 8 N-m. The indicated power of the engine is 2KW. Find the loss due to friction as the percentage of brake power.         (19.366%)
2.    An engine with 90% mechanical efficiency has rating of 38KW brake power. Estimate its indicated power and frictional power loss. Also determine the mechanical efficiency at quarter load assuming frictional power to remain same.       (42.22KW,4.22,69.24)         3.    A vertical single cylinder four stroke diesel engine has a bore=80 mm and stroke= 100mm. it develops a torque of 3.5 N-m. if the mechanical efficiency is 90%. Calculate the mean effective pressure of the engine.                            (97.22 Kpa)
4.    A diesel engine consumes fuel at the rate of 5.5 gm/sec and develops a power of 75KW. If the mechanical efficiency is 85%. The lower heating value if the fuel is 44MJ/kg. determine
a)    bsfc   (0.264kg/kwh)     
b)   isfc      (0.2244kg/kwh)
c)    Brake thermal efficiency    (31%)
d)   Indicated thermal efficiency    (36.36%)     
5.    A two stroke diesel engine was motored when the meter reading was 1.5 KW, then the test on the engine was carried out for one hour and following observations were recorded:
                    Brake torque=120 Nm                      Speed= 600 rpm          fuel used:2.5 kg              C_v=40.4 MJ/kg.Determine:                   a) brake power (7.54 KW)                                       b) indicated power (9.04 KW)                                       c) Mechanical efficiency (83.41%)                                            d) Indicated thermal efficiency   (32.30%)
6. In a test for four cylinder, four stroke engine has a diameter of 100mm, stroke=120 mm, speed of engine= 1800 rpm, fuel consumption of 0.2 kg/min, calorific value of fuel is 44000 KJ/kg. Difference in tension on either side of brake pulley=40kg, brake circumference is 300 cm. if the mechanical efficiency is 90%, determine
a) Brake thermal efficiency  (24.054)b) Indicated thermal efficiency (26.727)c) imep       (693.198 KPa)d) bsfc          (0.34 kg/kwh) 7. A gas turbine unit has a pressure ratio of 6 and maximum cycle temperature of 610 ^o C. the isentropic efficiencies if the compressor and turbine are 0.8 and 0.82 respectively. Determine the thermal efficiency and the power output in KW of an electric generator geared to the turbine when the air enters the compressor at 15⁰ C at the rate of 16 kg/sec. take C_p = 1.11 KJ/kgK and ɼ=1.333 for the combustion and expansion process.    (12.24%, 770.56KW)

8. Air enters the compressor of an ideal air-standard Brayton cycle at 100 KPa, 300 K. the compressor pressure is 10. The turbine inlet temperature is 1400 K. determine the thermal efficiency of the cycle for a generator effectiveness of 80%. Take C_p  =1.005 KJ/kgK and ɼ=1.4.                          (56.197%)

9. Air is drawn in a gas turbine unit at 15 degree Celsius. And 100 KPa and pressure ratio is 7. The compressor is driven by the HP turbine and LP turbine drives a separate power shaft. The isentropic efficiencies of compressor, and the HP and LP turbines are 0.82, 0.85, 0.85. If the maximum cycle temperature is 610 degree Celsius, calculate

      a) The pressure and temperature of the gases entering the low pressure turbine                (163.97 KPa, 654.76K)

b) The net power developed by the unit per kg per sec mass flow     ((74.378 KJ/kg)

c) The thermal efficiency of the unit

[for compression process C_pa= 1.005 KJ/kgK and ɼ=1.4 and for combustion and expansion processes: C_pg=1.15 KJ/kgK and ɼ=1.333)

10. Air enters the compressor at 100 KPA, 300 K and is compressed to 1000 KPa. The temperature at the inlet to the first turbine stage is 1400K. The expansion takes place isentropically in two stages, with reheat to 1400 K between the stages at constant pressure of 300 KPA. A regenerator having an effectiveness of 100% is also incorporated in the cycle. Determine the thermal efficiency. Take Cp= 1.005 KJ/kgK and r=1.4.                                                   (41.15%)

11. On a reheat cycle, steam leaves the boiler and enters the turbine at 4 MPa, 400 degree Celsius. After expansion in the turbine to 400 KPa, the steam is reheated to 400 degree Celsius and then expanded in the low pressure turbine to 10 KPa. Determine the cycle efficiency.                                                                 (35.87%)

12. a steam power plant running on Rankine cycle has steam entering HP turbine at 20 MPA, 500 degree Celsius and leaving LP turbine at 89.6% dryness. Considering condenser pressure of 0.005 MPA and reheating occurring up to the temperature of 500 degree Celsius. Determine:

                                a) The pressure at which steam leaves HP turbine   (1500 KPa)

                                b) The thermal efficiency             (44.417%)

13. a single running at 1800 rpm develops a torque of 8 N-m. the indicated power of the engine is 1.8 KW. Find the loss due to friction power as the percentage of IP.                                 (16.224%)

14. a 4-cylinder, 4 stroke cycle engine having cylinder diameter 100 mm and stroke 120 mm was tested at 1600 rpm and the following readings were obtained. Fuel consumption= 0.27 liters/minute, specific gravity of fuel= 0.74, BP= 31.4 KW, mechanical efficiency= 80%, C_v= 44000 KJ/kg. Determine

                                a) bsfc                                  (0.3817 kg/kwh)

                                 b) imep                             (780.854 KPa)

                                  c) brake thermal efficiency     (21.43 %)

15. A regenerative gas turbine with intercooling and reheat operates at steady state. Air enters the compressors at 1000 KPa, 300 K with a mass flow rate of 5.807 kg/sec. the pressure ratio across the two stage compressor is 10. The pressure ration across the two stage turbine is also 10. The intercooler and reheater each operate at 300 KPa. At the inlets to the turbine stages, the temperature is 1400 K. the temperature at the inlet to the second compressor stage is 300 K. the isentropic efficiency of each compressor and turbine stage is 80%. The regenerator effectiveness is 80%. Determine

                             a) Thermal efficiency

                              b) Back work ratio

                              c) Net power developed in KW

 [Take r=1.4, C_p=1.005KJ/kg]            (44.34%, 0.4655, 1957.496 KW)

16. Consider a regenerative cycle using steam as the working fluid. Steam leaves the boilers and enters the turbine at 4MPa, 400 degree Celsius. After expansion to 400 KPa, some of the steam is extracted from the turbine to heat the feed water in an open feed water heater. The pressure in the feed water heater is 400 KPa, and the water leaving it is saturated liquid at 400 KPa. The steam not extracted expands to 10 KPa. Determine the cycle efficiency.                (32.46%)

        

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