Internal Combustion Engine

Front 1

Who formulated Otto Cycle

Back 1

Nicholas Otto (1832-1891)

Front 2

What is internal Combustion engine?

Back 2

is an engine where the generation of heat is effected inside the work producing unit.

Front 3

What are the process plotting 1-2, 2-3 , 3-4, 4-1 in otto cycle?

Back 3

process 1-2 : Isentropic Compression

process 2-3 : Isometric Heat Addition

process 3-4 : Isentropic Expansion

process 4-1 : Isometric Heat Rejection

Front 4

1. An OTTO Engine has a clearance volume of 7%. It produces 300 kW of power. What is the amount of heat rejected in kW?

A. 170 C. 152

B. 160 D. 145

Back 4

C. 152

Front 5

2. An air standard engine has a compression ratio of 20 and a cut-off ratio of 5. If intake air pressure and temperature are 100 Kpa and 27Celsius , find the work in kJ/kg.

A. 2796 B. 2165 C. 2437 D. 2751

Back 5

B. 2165

Front 6

3. Determine the air-standard efficiency of an engine operating on the Diesel cycle when the suction is 99.97 kPa and the fuel is injected for 6% of the stroke, the clearance volume is 8% of the stroke. Assume k= 1.4

A. 60.07% B. 65.01% C. 67.01%

D. 64.02%

Back 6

A. 60.07%

Front 7

4. In an air standard OTTO cycle, the clearance volume is 18% of the displacement volume. Find the thermal efficiency.

A. 0.52 B. 0.55 C. 0.53 D. 0.60

Back 7

C. 0.53

Front 8

5. In an air standard Diesel Cycle, compression starts at 100 kPa and 300K. the compression ratio is 16 to 1. The maximum cycle temperature is 2031 K. Determine the thermal efficiency.

A. 60.27% B. 62.27 C. 63.27%

D. 64.27%

Back 8

A. 60.27%

Front 9

6. A diesel engine is operating on a 4-stroke cycle, has a heat rate of 11,315.6 kJ/kW-hr brake. The compression ratio is 13. The cut-off ratio is 2. Using k=1.32 what is the brake engine efficiency?

A. 63.5 B. 51.2 C. 73.5 D. 45.3

Back 9

A. 63.5

Front 10

7. The compression ratio of an ideal OTTO cyle is 6:1. Initial conditions are 101.3 kPa and 20celsius. Find the pressure and temperature at the end of adiabatic compression.

A. 1244.5 kPa, 599.96 K

B. 1244.5 KPa, 60 celsius

C. 1244.5 Kpag, 60 celsius

D. 1244.5 kPa, 599.96 celsius

Back 10

A. 1244.5 kPa, 599.96K

Front 11

Guess the formula of Heat Added (QsubA) in otto cycle

Back 11

QsubA = mCsubv (Tsub3 - Tsub2)

Front 12

Guess the formula of Net Work Done in otto cycle:

Back 12

Wsubnet = QsubA - QsubR

Front 13

Guess the formula of Cycle Efficience in otto cycle

Back 13

e = Wnet / QsubA

Front 14

Guess the formula of compression Ratio in otto cycle

Back 14

Rsubk =V1/V2 = V4/V3

Front 15

Guess the formula of Heat Rejected in Otto Cycle

Back 15

QR = MCv (T1 - T4 )

Front 16

Whats the formula of alternative efficiency

Back 16

e = 1 - [ 1 / (rk)^(k-1) ]

Front 17

Whats the formula of percentage clearance and rk using percentage clearance in otto cycle

Back 17

c = 1/ ( rk - 1 )

Rk = ( 1 + c ) / c

Front 18

Whats the formula of Volume Displacement

Back 18

VsubD = V1 - V2

Front 19

Whats the formula Clearance Volume

Back 19

Vc = cVD

Front 20

Whats the formula of Mean Effective Pressure in otto cycle

Back 20

Pm = Wnet / VD

Front 21

Who formulated Diesel Cycle?

Back 21

Rudolf Diesel ( 1858 - 1913 )

Front 22

What is the Diesel Cycle

Back 22

Is an ideal or air- standard cycle for compression-ignition engine ( Diesel Engine) . This cycle is a constant pressure Combustion cycle

Front 23

8. An engine operates on the air-standard OTTO cycle. The cycle work is 1000 kJ/kg. What is the compression ratio of the engine if the maximum cycle temperature is 3173 K and the temperature at the end of isentropic compression is 773 K.

A. 6.85 B. 8.85 C. 7.85 D. 9.85

Back 23

B. 8.85

Front 24

9. The conditions at the beginnning of compression in an OTTO engine operating on hot - air standard with k = 1.35 are 101.325 kPa, 0.05m^3 and 32 celsius. The clearance is 8% and 15 kJ are produced per cycle. Determine the mean effective pressure.

A. 323.97 kPa B. 423.97 kPa C. 223.97kpa D. 523.97 KPa

Back 24

A. 323.97 KPa

Front 25

10. The compression ratio of an OTTO cycle is 9. If the initial pressure is 150 KPa, determine the final pressure.

A. 1 251.10 Kpa B. 4 251.10 kPa

C. 2 251.10 kPa D. 3 251.10 kPa

Back 25

D. 3 251.10 kPa

Front 26

11. There are supplied 400 kJ per cycle to an ideal Diesel engine operating on m = 500 g air, P1 = 100 kPa, t1 = 50 celsius. At the end of compression, P2 = 4000 kPa. Determine the effective pressure of the engine.

A. 657.57 kPa B. 457.57 kPa

C. 557.57 kPa D. 357.57 kPa

Back 26

C. 557.57 kpa

Front 27

12.What is the final temperature after compression of a diesel cycle if the initial temperature is 32 celsius and the clearance is 8%

A. 863.84 K C. 963.84K

B. 763.84 K D. 663.84 K

Back 27

A. 863.84 K

Front 28

13. An Ideal dual cycle combustion cycle operates on 500 gram of air. At the beginning of the compression, the air is at 100 Kpa, 45 celsius. If rsubp = 1.5, rsubc = 1.65, and rk= 10, determine the cycle efficiency.

A. 53.88% C. 55.88%

B. 54.88% D. 56.88%

Back 28

D. 56.88%

Front 29

14. The compression ratio of an engine working on the constant volume cycle is 9.3 to 1. At the beginning of compression the temperature is 31°C and at the end of Combustion the temperature is 1205°C. Taking the compression and expansion to be adiabatic and the value of k as 1.4. Calculate the theoritical thermal efficiency.

A. 59.02% C. 58.02%

B. 54.02 % D. 56.02 %

Back 29

A. 59.02 %

Front 30

15. The compression ratio in a Diesel engine 13 to 1 and the ratio of expansion is 6.5 to 1. At the beginning of compression the temperature is 32°C. Assuming adiabatic compression and expansion calculate the ideal thermal efficiency taking the specific heats at constant pressure and volume as 1.005 kJ/kg and 0.718 kJ/kg•K. Respectively.

A. 54% B. 56% C. 58% D. 52%

Back 30

C. 58%

Front 31

16. The stroke of a gas engine which works on the constant volume cycle is 450 mm. The pressure at the beginning of the compressio is 1.01 bar and at the end of compression it is 11.1 bar. Assuming compression follows the law PV^1.36 = C, calculate the clearance between the piston and cylinder cover at the end of compression in mm of length.

A. 73.26 mm. C. 93.26 mm

B. 83.26 mm. D. 103.26 mm

Back 31

D. 93.26 mm

Front 32

17. The ratio of compression in a Diesel engine is 16 to 1 and the temperature of the air at the beginning of the compression is 49°C. Calculate the temperature at the end of compression assuming it follows the law PV^1.34 = C

A. 826.53°C. C. 453.43°C

B. 553.53°C. D. 653.53°C

Back 32

B. 553.53 ° C

Front 33

18. The stroke of the piston in an internal combustion engine is 880 mm and the clearance is equal to 80 mm. The law of compression is PV^1.38 = C and the pressure at the end of compression is 32 bar. Find the increase of the final pressure caused by reducing clearance by 5 mm.

A. 3.82 bar. C. 2.82 bar

B. 1.82 bar. D. 4.82 bar

Back 33

C. 2.82 bar

Front 34

19. In an internal combustion engine working on the constant volume cycle, the pressure, volume and the temperature at the beginning of compression are 101.325 kPa , 113 liters and 48°C respectively, and the ratio of compression is 10. During combustion at constant volume the gas receives 95 kJ of heat at constant volume 0.712 kJ/kg•K and gas constant R = 0.29 kJ/kg•K, calculate the mass of gas compressed.

A. 0.123 kg. C. 0.346 kg

B. 0.245 kg. D. 0.456 kg

Back 34

A. 0.123 kg

Front 35

20. The pressure and temperature of the air at the beginning of compressionin a diesel engine is 111.46 kPa and 35°C respectively, and the clearance volume is equal to 7.5% of the piston swept volume. Calculate the pressure at the end of compression assuming the law of compression if PV^1.36 = C

A. 352.83 kPa. C. 4,166.31 kPa

B. 8,082.90 kPa. D. 41.11 Kpa

Back 35

C. 4,166.31 kPa

Front 36

21. The stroke of a petrol engine is 87.5 mm and the clearance is equal to 12.5 mm. A compression plate is now fitted which has the effect of reducing the clearance to 10 mm. Assuming the compression period to be the whole stroke, the pressure at the beginning of compression as 98.29 kPa and the law of compression PV^1.35 = C , calculate the pressure at the end of compression before and after compression is fitted.

A. 1628.10 kPa. C. 1728.10 Kpa

B. 1528.10 kPa. D. 1828.10 Kpa

Back 36

A. 1628.10 Kpa

Front 37

22. The compression ratio of a petrol engine working on the constant volume cycle is 8.5 . The pressure and the temperature at the beginning of compression are 101.325 kPa and 40°C and the maximum pressure of the cycle is 3,141.08 kPa. Taking compression to follow the law PV^1.35 = C, calculate the temperature at the end of compression.

A. 388.97 °C. C. 355.65 °C

B. 288.97° C. D. 255.65 °C

Back 37

A. 388.97 °C

Front 38

23. The stroke of an internal combustion engine is 75 mm, the diameter of the cylinder is 70 mm and the clearance volume at the end of compression is 36 cm^3. Assuming compression follows the law PV^1.37 = C. Calculate the pressure at the end of compression if the initial pressure is 98.29 kPa.

A. 1mpa C. 3 mpa

B. 2 mpa D. 4 mpa

Back 38

B. 2 mpa

Front 39

24. A petrol engine working on the constant volume cycle has a compression ratio 9 to 1. If the pressure and temperature of the petrol-vapor air mixture at the beginninf of compression are 99.30 kPa and 38°C resprectively. Calculate the temperature at the end of compression assuming it follows the law PV^1.34=C.

A. 383.45 °C C. 899.30°C

B. 728.45 °C D. 883.48°C

Back 39

A. 383.45 °C

Front 40

25. When the piston is moving up in a two-stroke diesel engine, the scavenge ports are closed when the piston is 675 mm from the top of its stroke, the pressure and temperature of the air in the cylinder then being 13.80 kPag and 43°C. The clearance is equal to 65 mm and the diameter of the cylinder is 650mm. Calculate the mass of air comressed in the cylinder taking the atmospheric pressure as 101.325 kPa and R for air as 0.287 kJ/kg•K.

A. 0.21 kg C. 0.41 kg

B. 0.31 kg D. 0.51 kg

Back 40

B. 0.31 kg

Front 41

26. The compression ratio of a compression-ignition engine is 14 to 1. The diameter of the cylinder is 500 mm and the sroke to bore ratio is 1.2 to 1. At the beginning of the compression the pressure and temperature of the air in the cylinder is 105 kPa and 51°C, and compression follows the law PV^n = C, where n =1.35. Calculate the work done on the air during compression.

A. -57.69 kJ C. -76.59 kJ

B. -67.59 kJ D. -95.67 kJ

Back 41

A. -57.69 kJ

Front 42

27. Gas initially at a pressure of 101.325 kPa and temperature of 60°C undergoes the ff. cycle:

1-2 Adiabatic compression through compression ratio 4.5:1

2-3 Heating at constant vlume through a pressure ratio of 1.35:1

3-4 Constant pressure expansion to initial pressure

4-1 Constant pressure cooling to initial volume

if Cp = 1 kj/kg-K % Cv = 0.6789 kJ/kg-K for the gas, determine the thermal efficiency of the cycle.

A. 41.41% B. 39.39% C. 43.343%

D. 45.45%

Back 42

A. 41.41%

Front 43

28. One kilogram of air at pressure and temperature of 101.325 KPa and 15°C initially, undergoes the ff. process in a cycle:

1-2 Isothermal compression to 202.65 kPa

2-3 Polytropic compression from 202.65 kPa to 405.30 KPa

3-1 Isentropic expansion from 405.30 kPa to initial condition

Calculate the heat transfer for process 1 to 2. Use R= 0.287 kj/kg-K and k=1.4 for air.

A. -57.29kJ C. 70.30 kJ

B. -30.21 kJ D. 100.50 kJ

Back 43

A. -57.29 kJ

Front 44

29. The compression ratio of an engine working on the dual combustion cycle is 10.7 The pressure and temperature of the air at the beginning of compression is 101.325 kPa and 32°C. The maximum pressure and temperature during cycle is 4.154 MPa and 1593°C. Assuming adiabatic compression and expansion, calculate the temperature at the end of compression.

A. 414.14°C C. 314.14°C

B. 514.14 °C D. 614.14°C

Back 44

B. 514.14°C

Front 45

30. In an Otto cycle if the compression ratio is 5.5, what is the percent clearance?

A. 22.22 % C. 19.64 %

B. 31.11 % D. 25.34%

Back 45

A. 22.22 %

Front 46

31. The efficiency of an Otto engine is 55% and the stroke volume is 35 liters. If the heat added at the beginning of the combustion is 12.6 kJ, calculate the mean effective pressure.

A. 194 KPa C. 198 kPa

B. 188 KPa D. 184 KPa

Back 46

C. 198 kPa

Front 47

32. Gas is compressed in an internal combustion engine accordning to the law PV^1.36 = C. If the initial and final temperature of the gas are 30°C and 382 °C respectively, calculate the compression ratio.

A. 551 B. 6.51 C. 7.51 D. 8.51

Back 47

D. 8.51

Front 48

33. If the volumes at the end of compression and at the beginning of expansion in an ideal Diesel engine are 0.015 m^3 and 0.040 m^3 respectively. What is the cut-off ratio?

A. 1.67 C. 2.54

B. 2.67 D. 1.54

Back 48

B. 2.67

Front 49

34. The pressure ratio during the constant volume portion of combustion in a dual combustion engine is 1.5. If the pressure at the end of the constant volume addition of heat is 4, what is the pressure at the beginning?

A. 3.67 Mpa C. 2.67 Mpa

B. 6 Mpa D. 7 Mpa

Back 49

C. 2.67 Mpa

Front 50

35. If the compression ratio and the cut-off ratio of a DIesel Engine are 15 and 3 respectively, what is the expansion ratio?

A. 4 B. 5 C. 6 D. 7

Back 50

B. 5

Front 51

36. At the beginning of compression in an ideal dual combustion cycle, the working fluid is 2lbs of air at 14.7 psia and 85°F. The compression ratio is 8.5, the pressure at the end of the constant volume addition of heat is 450 psia, and there are added 105 BTU during the constant pressure expansion. Find the pressure ratio and the percentage clearance?

A. 1.53 , 13.33 % C. 1.53, 12.42%

B. 1.31 , 12.42% D. 1.31, 13.33%

Back 51

A. 1.53 , 13.33 %

Front 52

37. What is the efficiency of the DIesel Engine if the heat added during the constant pressure combustion is 19 BTU and the heat rejected is 9 BTU.

A. 42.63% C. 55.66 %

B. 52.63% D. 45.66%

Back 52

B. 52.63%

Front 53

38. A diesel cycle operates with a compression ratio of 14 and with a cut-off occuring at 5% of the stroke. Find the cut -off ratio, if the initial volume is 1.5 ft^3.

A. 1.64 C. 3.64

B. 2.64 D. 4.64

Back 53

A. 1.64

Front 54

39. The air is compressed to 1/5 of its original volume in an OTTO cycle. What is the final temperature of the air if the initial temperature is 25 °C

A. 294.29°C C. 255.66°C

B. 388.58°C D. 355.66°C

Back 54

A. 294.29 °C

Front 55

40. An otto cycle operates 1 kg of air from 101.235 KPA and 25°C at the beginning of compression. iF the clearance is 15%, find the temperature at the end of compression

A. 300 °C C. 450.01°C

B. 400°C D. 350.01°C

Back 55

B. 400°C

Front 56

41. The compression ratio and the cut-off ratio of an ideal diesel cycle are 13 amd 3 respectively. what is the cycle efficiency for a cold-air standard value of k.

A. 53.20% C. 55.21%

B. 42.20 % D. 45.21%

Back 56

A. 53.20%

Front 57

42. The efficiency of an ideal otto cycle is 40%. WHat of the hot-air value of K, if the compression ratio is 6.2?

A. 1.28 C. 1.25

B. 1.38 D. 1.35

Back 57

A. 1.28