Assign 1 - Power Plant Design with Renewable Energy Problem Solving (1-33) PDF

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I POWER PLANT An 850-kWh diesel generating unit has a generator efficiency of 90 percent. If the mass of the fuel is 209 kilograms, then compute for the engine fuel rate. A single-acting, four cylinder, 4-stroke cycle diesel engine with a bore to stroke of 21 x 27 cm., operating at 275 rpm, consumes...

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I.DIESEL POWER PLANT

1. An 850-kWh diesel generating unit has a generator efficiency of 90 percent. If the mass of the fuel is 209 kilograms, then compute for the engine fuel rate.

2. A single-acting, four cylinder, 4-stroke cycle diesel engine with a bore to stroke of 21.59 x 27.94 cm., operating at 275 rpm, consumes 8.189 kg/hr of fuel whose heating value is 43,961.4 kJ/kg. The indicated mean effective pressure is 475.7 kPa. The load on the brake arm, which is 93.98 cm is 113.4 kg. What is the brake arm mean effective pressure in kPa?

3. A 20 cm x 35 cm diesel engine with 4 cylinders and operating on a four-stroke, has a rated power of 160 kW and is running at 250 rpm. Find the volume displacement per brakepower developed.

4. A 25 cm x 38 cm cylinder, four-stroke and 4 cylinders engine running at 260 rpm. The engine rate is 150 kW. Determine engine displacement per brakepower.

5. An engine burns a liter of fuel each 12 minutes. The fuel has specific gravity of 0.8 and a heating value of 45 MJ/kg. The engine has an efficiency of 25%. What is the brake horsepower of the engine?

6. In a double-acting, 2 stroke compression ignition engine, 8cylinder, the diameter of the cylinder is 700 mm, stroke 1350 mm and the piston rod diameter is 250 mm. When running at 108 rpm, the indicated mean effective pressures above and below the pistons are 5.8 bar and 4.9 bar respectively. Calculate the brake power of the engine with a mechanical efficiency of 80% in kilowatts.

7. A six cylinder, four-stroke diesel engine with 76 mm bore x 89 mm stroke was run in the laboratory at 2000 rpm, when it was found that the engine torque was 153.5 N-m with all the cylinders firing but 123 N-m when one cylinder was out. The engine consumed 12.2 kg of fuel per hour with a heating value of 54,120 kJ/kg and 252.2 kg of air at 15.6°C per hour. Determine the indicated power.

8. A single-acting, four cylinder, 4-stroke cycle diesel engine with a bore to stroke of 21.59 x 27.94 cm, operating at 275 rpm, consumes 8.189 kg/hr of fuel whose heating value is 43,961.4 kJ/kg. The indicated mean effective pressure is 475.7 kPa. The load on the brake arm, which is 93.98 cm is 113.4 kg. What is the brake arm mean effective pressure in kPa?

9. A diesel electric plant supplies energy for Meralco. During a 24hour period, the plant consumed 200 gallons of fuel at 28 °C and produced 3930 kW-h. Industrial fuel used is 28°API and was

purchased at P 5.50 per liter at 15.6°C. What should the cost of fuel be to produce one kW-h?

10. A four cylinder, four-stroke cycle diesel engine with 20 cm bore x 25 cm stroke running at 550 rpm has a mean effective pressure of 150 psi. Calculate the brake power in kW if engine efficiency is 88%.

11. A four stroke, direct injection diesel engine of 4 in. bore and 4.5 in stroke develops 45 Hp at full load and 8 Hp when running at idling load. Engine speed is 2,200 rpm. What is the mechanical efficiency?

12. A 500 kW diesel engine has a heat rate of 12,00 kJ/kW-hr. The compression ratio is 16:1, cut-off ratio of 2.3. Assume k = 1.32. Calculate the engine efficiency based on the output of 500 kW.

13. If the brake mean effective pressure of a diesel engine is 500 kPa and the mechanical efficiency is 85%, what is the indicated mean effective pressure?

14. The brake thermal efficiency of a 1 MW diesel electric plant is 36%. Find the heat generated by fuel in kW if the generator efficiency is 89%.

15. A 500 kW diesel engine develops torque of 2 kN-m. The engine drives an alternating current generator with 8-poles producing current at 60 Hz. What is the speed ratio of speed reduction gear?

16. A diesel engine is operating on a 4 stroke cycle has a heat rate of 8000 BTU/Hp-hr. The compression ratio is 13, cut-off ratio is 2 and k = 1.32. Find the brake engine efficiency.

17. What is the mechanical efficiency of a 0.5 MW diesel engine if the friction power is 70 kW.

18. The area of an indicator diagram taken off a four-cylinder, single acting, four-stroke engine when running at 5.5 rev/s is 390 mm2, the length is 70 mm and the scale of the indicator spring is 1 mm = 0.8 bar. The diameter of the cylinders is 150 mm and the stroke is 200 mm. Calculate the indicated power of the engine assuming all cylinders develop equal power.

19. The cylinder diameter of an 8-cylinders, single acting, 4-stroke diesel engine are 750 mm and the stroke is 1125 mm. The indicated mean effective pressure in the cylinders is 586 kPa when the engine is running at 110 rpm. Calculate the brake power if the mechanical efficiency is 86%.

20. Calculate the cylinder diameter and stroke of a 6-cylinder, single acting, two-stroke diesel engine to develop a brake power of 1125 kW at a rotational speed of 2 rev/s when the indicated mean

effective pressure in each cylinder is 5 bar. Assume a mechanical efficiency of 84% and make the length of the stroke 25% greater than the diameter of the cylinders.

21. In a single-acting, two stroke, opposed-piston diesel engine, the ratio of the masses of the top piston and its connected moving parts to the bottom piston and its moving parts is 7.5 to 6, and the strokes of the pistons are in inverse ratio of their masses. The combined stroke of the top and bottom pistons is 2430 mm. Find the strokes of the top and bottom pistons.

22. In an 8-cylinder, double acting, two-stroke compression ignition engine, the diameter of the cylinders is 700 mm, stroke 1350 mm and the piston rod diameter is 250 mm. When running at 1.8 rev/s, the indicated mean effective pressures above and below the pistons are 5.8 and 4.9 bars respectively. Calculate the indicated power developed above and below the piston in each cylinder.

23. The flywheel of a rope brake is 1.22 m diameter and the rope is 24 mm diameter. When the diesel engine is running at 250 rev/min

the load on the brake is 480 N on one end of the rope and 84 N on the other end. Calculate the brake power.

24. A compression-ignition engine under test was coupled to a hydraulic dynamometer, the brake power formula in kW for this dynamometer is where W = brake loads in Newtons. When the engine was running at 50 rev/s the brake load was 180 N, mass flow of water through the brake, 1218 kg/hr with inlet temperature at 16.4°C and outlet 36.9°C. Calculate what percentage of the heat generated at the brake is carried away by the cooling water.

25. When developing a certain power, the specific fuel consumption of an engine is 0.255 kg/kW-hr and the mechanical efficiency is 86%. Calculate the indicated thermal efficiency. The heating value of fuel is 43.5 MJ/kg.

26. A diesel engine uses 27 tons of fuel per day when developing 4960 kW indicated power and 4060 kW brake power. Of the total heat supplied to the engine, 31.7% is carried away by the cooling water and radiation, and 30.8% in the exhaust gases. Calculate the heating value of the fuel.

27. The specific brake fuel consumption of a diesel engine is 0.243 kg/kW-hr when developing 2600 kW brake power, the calorific value of the fuel being 42 MJ/kg. Forty tons of lubricating oil circulate through the engine per hour, the inlet temperature is 24 °C and the outlet 49°C. Taking the specific heat of the lubricating oil as 2.1 kJ/kg-K, calculate the heat carried away by it as a percentage of the heat supplied to the engine.

28. The mean effective pressure measured from the indicator diagram taken off a single-cylinder, four-stroke diesel engine was 3.93 bar when running at 5 rev/s and developing a brake power of 4.33 kW. The number of explosion per minute was 123 and the gas consumption was 3.1 m3/hr. The diameter of the cylinder is 180 mm, stroke 300 mm and calorific value of the fuel is 17.6 MJ/m 3. Calculate the brake thermal efficiency.

29. Air is compressed in a diesel engine from 1.17 bar to 36.55 bar. If the temperature at the beginning ad end of the compression are 32°C and 500°C respectively, find the law of compression assuming it is polytropic.

30. A single acting, 8 cylinder, 4 stroke diesel engine with a bore to stroke of 142.10 mm × 210.45 mm operates at 1,200 rpm. The load on the brake arm at 1 m is 150 kg. What is the brake mean effective pressure in kPa?

31. A 16-cylinder, V-type diesel engine is directly coupled to ¾ MW AC generator. Calculate the brake power of the engine if generator efficiency is 90%.

32. An engine on test developed 154 BHP steadily for 30 minutes during which it consumed 15.34 kg fuel. This same fuel when tested at 23.9°C with a 15.6°C hydrometer, showed SG of 0.905. Calculate thermal efficiency based on BHP and Qh.

33. What ideal thermal efficiency is possible from a diesel having a compression ratio of 15, A:F = 40:1, QA = 42,800 kJ/kg? Take Cp = 1.05 kJ/kg-K and t1 = 15.6°C....