Test 2

99問 • 3年前

Jacky Shane Luyas Buhia

通報

問題一覧

1. Improving the efficiency of an air-standard Otto cycle engine depends chiefly on

A. increasing the compression ratio

2. Increasing the piston diameter or piston stroke of Otto cycle engine will

B. increase the efficiency of the engine

3. The work output per cycle also depends strongly on the compression ratio as well as the

D. volumetric displacement of the engine

4. The mean effective pressure of Otto cycle can be increased by increasing the heat transfer into the engine per cycle or by

C. increasing pressure ratio

5. _________the engine in Otto cycle can increase the power of the cycle but not to increase efficiency.

C. Supercharging

6. A _________is used in aircraft engines and some automotive engine. In this method, a turbine driven by the exhaust gases is used to provide power to compressor or blower at the inlet.

B. turbocharging

7. The practical disadvantage of supercharging is that the pressure P3 will be greater in the supercharge engine, resulting in

B. knocking

8. Most supercharged of turbo-charged engines use fuel injection of gasoline directly to

D. combustion chamber

9. A diesel cycle has two isentropic, one constant pressure and one.

B. constant volume process

10. The ideal cycles are

B. internally reversible

11. The thermal efficiency of an ideal cycle is less than that of a totally reversible cycle operating between

B. temperature limits

12. The only devices where the changes in kinetic energy are significant are the

C. nozzles and diffusers

13. The T-s diagram is useful in the analysis of

B. ideal power cycles

14. Equations pertaining to steady flow systems should be used in the analysis of

D. Rankine cycle

15. Equations pertaining to closed systems should be used in the analysis of

A. Otto cycle

16. The Carnot cycle is a function of the

D. sink and source temperature

17. Thermal efficiency of Carnot cycle increases with_______ at which heat is added to the system or with a decrease in the average temperature at which heat is rejected from the system.

B. an increase in average temperature

18. Spark-ignition automobile engines, diesel engines, and the conventional gas turbines are devices which operates on_______. They are also internal combustion engines

B. gas cycles

19. Another assumption which is often utilized to simplify the analysis of air standard assumptions is that air has whose value are determined at room temperature (25°C).

D. constant specific heat

20. A cycle for which the air-standard assumptions are applicable is frequently referred as

D. air standard cycle

21._______________ basically a piston-cylinder device.

D. reciprocating engine

22. is the position of the piston when in the cylinder. it forms the smallest volume

B. Top dead center

23. is the position of the piston when it forms the largest volume in the cylinder.

C. Bottom dead center

24. The distance between TDC and BDC in which the piston can travel is the

C. stroke of the engine

25. The diameter of the piston is called

C. bore

26. The air or air-fuel mixture is drawn into the cylinder through the

A. intake valve

27. The combustion products are expelled from the cylinder through the

C. exhaust valve

28. The minimum volume formed in the cylinder when the piston is at TDC is called the

D. clearance volume

29. The volume displaced by the piston as it moves between TDC and BDC is called

D. displacement volume

30. The ratio of the maximum volume formed in the cylinder to the minimum volume is called the of the engine.

D. compression ratio

31. Compression ratio is a

D. volume ratio

32.________________is the fictitious pressure which, if it acted on the piston during the entire power stroke, would produce the same amount of work as that produced during the actual cycle.

D. Mean effective pressure

33. Reciprocating engines are classified as a

A. Spark-ignition engines or compression ignition engines

34. In spark-ignition engine, the combustion n the air-fuel mixture is initiated by a

D. spark plug

35. In compression-engine, the combustion of air-fuel mixture is self-ignited as a result of compressing the mixture above its

D. self-ignition temperature

36. _________________ the piston executes four complete strokes (two mechanical cycles) within the cylinder, and crankshaft completes 2 revolutions for each thermodynamic cycle.

D. Four stroke internal combustion engine

37. Initially, both the intake and the exhaust valves are closed, and the piston is at its

B. lowest position

38. During compression stroke, the piston moves_________, compressing the air-fuel mixture.

D. upward

39. Shortly before the piston reaches its highest position, the spark plug fires _________ of the system.

C. increasing the pressure and temperature

40. In 4 stroke cycle, the useful output is done during the

B. expansion or compression stroke

41. The pressure in the cylinder is _________ during the exhaust stroke and slightly below during intake stroke.

A. slightly above

42. Two stroke engine performs intake, compression, expansion, and exhaust stroke in __________ only.

D. two revolutions

43. Two stroke engines are generally __________ than four-stroke engines because of isentropic expulsion of the exhaust gases and partial expulsion of fresh air-fuel mixture with the exhaust gases.

A. less efficient

44. Two stroke engine are relatively __________ and have high power-to-weight and power-to volume ratios. which make them suitable for applications requiring small size and weight such as for motorcycles, chain saws, and lawn mowers.

C. simple and inexpensive

45. Two stroke engines has __________ compared to four stroke engines.

B. more power

46. The thermal efficiency of an ideal Otto cycle depends _______ of the working fluid.

D. the compression ratio of the engine and the specific heat ratio

47. The thermal efficiency of Otto cycle increases as the compression ratio.

A. increases

48. Typical compression ratio of Otto cycle is

C. 8.0

49. The premature ignition of the fuel is called

B. autoignition

50. Autoignition in spark-ignition engine can ________ to the engine.

C. cause damage

51. ___________ has been added to gasoline because it is the cheapest method of raising the octane rating.

A. Tetraethyl lead

52. Is a measure of the engine knock resistance of a fuel.

C. Octane rating

53. Leaded gasoline engine has

C. undesirable side effect

54. Most cars have been designed to use unleaded gasoline and the compression ratio had to be lowered to avoid

D. engine knock

55. The thermal efficiency of car engines has been decreased somewhat as a result

B. decreased compression ratio

56. The second parameter affecting the thermal efficiency of an ideal Otto cycle is the

C. specific heat ratio

57.Using monatomic gas, the thermal efficiency of Otto cycle

A. increases

58. The thermal efficiency of actual spark-ignition engines range from about

A. 25 to 30 %

59. The diesel engine is the ideal for CI (compression ignition) is

A. reciprocating engine

60. Invented diesel engine is_________ in the 1890.

D. Rudolph Diesel

61. If the density of air increases if its _________ will increase.

D. pressure

62. The difference between enthaipy and workflow is

B. internal energy77777

63. At critical point of T-s diagram in Rankine cycle the, what is the relation of saturated enthalpy of liquid and vapor?

A. hr hg

64. At one point of a pipe, x = volume flow of liquid, y= specific volume of liquid. The mass flow of liquid is

A. y

65. The fuel used in diesel is __________ than in the fuel used in gasoline engine.

A. less expensive

66. The fuel injection process in diesel engines starts when the piston_______ during the first part of power stroke.

B. before TDC

67. In diesel engine, combustion process during combustion occurs during

B. constant pressure process

68. The Otto and Diesel cycle differs during

D. combustion process

69. A measure of performance for any power cycle is its

B. thermal efficiency

70. Is the ratio of cylinder volumes after and before the combustion process.

C. cut-off ratio

71. The thermal efficiency of Otto cycle is always ____ the thermal efficiency of Diesel cycle when both cycle operates in the same compression ratio.

A. greater than

73. If the cutoff ratio is decreases, the efficiency of diesel cycle

A. increases

74. The diesel engines also burn the fuel more completely since they usually operate _____ than spark ignition engines.

C. lower revolutions per minute

75. Thermal efficiencies of diesel engines range from about

D. 35 to 40%

76. The________ of diesel engines make them the clear choice in applications requiring relatively large amounts of power, such as locomotive engines, emergency power generation units, large ships, and heavy trucks.

A. higher efficiency and lower fuel costs

77. A diesel engine can be built as much as _______ at 122 rpm.

C. 25,200 hp

78. A better approach would be to model the combustion process in both gasoline and diesel engines as a combination of two heat transfer process. This process is known as

D. Dual cycle

79. In dual cycle, the heat is added during constant volume and_____ process.

B. constant pressure

80. ______ is the process during which heat is transferred to a thermal energy storage device.

B. regeneration

81. The regenerator is a device that borrows ______ from the working fluid during one part of the cycle and pays it back during another part of the cycle.

B. Energy

82. In Stirling cycle, regeneration process works during______ process.

A. constant volume

83. In Ericsson cycle, the regeneration process occurs during _______ process

C. constant pressure

84. Invented Stirling engine is _______ very heavy and complicated.

D. Robert Stirling

85. Both the Stirling and Ericsson cycles are totally reversible as is the

A. Carnot cycle

86._______ have the same efficiency when operating the same temperature limits.

C. Stirling, Ericsson and Carnot cycles

87. Both the Stirling and Ericsson cycles are

B. external combustion engines

88. Are two gasses commonly employed in Stirling and Ericsson cycles

A. Hydrogen and Helium

89. Advantage of Stirling and Ericsson cycle:

D. All of these

90. In Stirling cycle, Regeneration can

B. increase efficiency

91. Brayton cycle is invented by

D. George Brayton

92. Gas turbines usually operates on an

B. open cycle

93. In gas turbine, the gas is expanded to the

A. vacuum pressure

94. Brayton cycle is made up of_________internally reversible process.

D. four

95. In Brayton cycle, the, ________during constant pressure process

B. heat is transferred

96. The thermal efficiency of an ideal Brayton cycle depends on

D. pressure ratio of the gas turbine and specific heat ratio

97. The highest Temperature of gas turbine cycle occurs at the end of

C. combustion process

98. For a fixed turbine inlet temperature, the net work output per cycle increases with the pressure ratio, reaches the maximum, and then starts to

B. decrease

99. In most common designs of Gas turbines, the pressure ratio ranges from

B. 11 to 16

100. In gas turbines, an air-fuel mass ratio of ______ is not uncommon

D. 50 or above

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問題一覧

1. Improving the efficiency of an air-standard Otto cycle engine depends chiefly on

A. increasing the compression ratio

2. Increasing the piston diameter or piston stroke of Otto cycle engine will

B. increase the efficiency of the engine

3. The work output per cycle also depends strongly on the compression ratio as well as the

D. volumetric displacement of the engine

4. The mean effective pressure of Otto cycle can be increased by increasing the heat transfer into the engine per cycle or by

C. increasing pressure ratio

5. _________the engine in Otto cycle can increase the power of the cycle but not to increase efficiency.

C. Supercharging

6. A _________is used in aircraft engines and some automotive engine. In this method, a turbine driven by the exhaust gases is used to provide power to compressor or blower at the inlet.

B. turbocharging

7. The practical disadvantage of supercharging is that the pressure P3 will be greater in the supercharge engine, resulting in

B. knocking

8. Most supercharged of turbo-charged engines use fuel injection of gasoline directly to

D. combustion chamber

9. A diesel cycle has two isentropic, one constant pressure and one.

B. constant volume process

10. The ideal cycles are

B. internally reversible

11. The thermal efficiency of an ideal cycle is less than that of a totally reversible cycle operating between

B. temperature limits

12. The only devices where the changes in kinetic energy are significant are the

C. nozzles and diffusers

13. The T-s diagram is useful in the analysis of

B. ideal power cycles

14. Equations pertaining to steady flow systems should be used in the analysis of

D. Rankine cycle

15. Equations pertaining to closed systems should be used in the analysis of

A. Otto cycle

16. The Carnot cycle is a function of the

D. sink and source temperature

17. Thermal efficiency of Carnot cycle increases with_______ at which heat is added to the system or with a decrease in the average temperature at which heat is rejected from the system.

B. an increase in average temperature

18. Spark-ignition automobile engines, diesel engines, and the conventional gas turbines are devices which operates on_______. They are also internal combustion engines

B. gas cycles

19. Another assumption which is often utilized to simplify the analysis of air standard assumptions is that air has whose value are determined at room temperature (25°C).

D. constant specific heat

20. A cycle for which the air-standard assumptions are applicable is frequently referred as

D. air standard cycle

21._______________ basically a piston-cylinder device.

D. reciprocating engine

22. is the position of the piston when in the cylinder. it forms the smallest volume

B. Top dead center

23. is the position of the piston when it forms the largest volume in the cylinder.

C. Bottom dead center

24. The distance between TDC and BDC in which the piston can travel is the

C. stroke of the engine

25. The diameter of the piston is called

C. bore

26. The air or air-fuel mixture is drawn into the cylinder through the

A. intake valve

27. The combustion products are expelled from the cylinder through the

C. exhaust valve

28. The minimum volume formed in the cylinder when the piston is at TDC is called the

D. clearance volume

29. The volume displaced by the piston as it moves between TDC and BDC is called

D. displacement volume

30. The ratio of the maximum volume formed in the cylinder to the minimum volume is called the of the engine.

D. compression ratio

31. Compression ratio is a

D. volume ratio

32.________________is the fictitious pressure which, if it acted on the piston during the entire power stroke, would produce the same amount of work as that produced during the actual cycle.

D. Mean effective pressure

33. Reciprocating engines are classified as a

A. Spark-ignition engines or compression ignition engines

34. In spark-ignition engine, the combustion n the air-fuel mixture is initiated by a

D. spark plug

35. In compression-engine, the combustion of air-fuel mixture is self-ignited as a result of compressing the mixture above its

D. self-ignition temperature

36. _________________ the piston executes four complete strokes (two mechanical cycles) within the cylinder, and crankshaft completes 2 revolutions for each thermodynamic cycle.

D. Four stroke internal combustion engine

37. Initially, both the intake and the exhaust valves are closed, and the piston is at its

B. lowest position

38. During compression stroke, the piston moves_________, compressing the air-fuel mixture.

D. upward

39. Shortly before the piston reaches its highest position, the spark plug fires _________ of the system.

C. increasing the pressure and temperature

40. In 4 stroke cycle, the useful output is done during the

B. expansion or compression stroke

41. The pressure in the cylinder is _________ during the exhaust stroke and slightly below during intake stroke.

A. slightly above

42. Two stroke engine performs intake, compression, expansion, and exhaust stroke in __________ only.

D. two revolutions

43. Two stroke engines are generally __________ than four-stroke engines because of isentropic expulsion of the exhaust gases and partial expulsion of fresh air-fuel mixture with the exhaust gases.

A. less efficient

C. simple and inexpensive

45. Two stroke engines has __________ compared to four stroke engines.

B. more power

46. The thermal efficiency of an ideal Otto cycle depends _______ of the working fluid.

D. the compression ratio of the engine and the specific heat ratio

47. The thermal efficiency of Otto cycle increases as the compression ratio.

A. increases

48. Typical compression ratio of Otto cycle is

C. 8.0

49. The premature ignition of the fuel is called

B. autoignition

50. Autoignition in spark-ignition engine can ________ to the engine.

C. cause damage

51. ___________ has been added to gasoline because it is the cheapest method of raising the octane rating.

A. Tetraethyl lead

52. Is a measure of the engine knock resistance of a fuel.

C. Octane rating

53. Leaded gasoline engine has

C. undesirable side effect

54. Most cars have been designed to use unleaded gasoline and the compression ratio had to be lowered to avoid

D. engine knock

55. The thermal efficiency of car engines has been decreased somewhat as a result

B. decreased compression ratio

56. The second parameter affecting the thermal efficiency of an ideal Otto cycle is the

C. specific heat ratio

57.Using monatomic gas, the thermal efficiency of Otto cycle

A. increases

58. The thermal efficiency of actual spark-ignition engines range from about

A. 25 to 30 %

59. The diesel engine is the ideal for CI (compression ignition) is

A. reciprocating engine

60. Invented diesel engine is_________ in the 1890.

D. Rudolph Diesel

61. If the density of air increases if its _________ will increase.

D. pressure

62. The difference between enthaipy and workflow is

B. internal energy77777

63. At critical point of T-s diagram in Rankine cycle the, what is the relation of saturated enthalpy of liquid and vapor?

A. hr hg

64. At one point of a pipe, x = volume flow of liquid, y= specific volume of liquid. The mass flow of liquid is

A. y

65. The fuel used in diesel is __________ than in the fuel used in gasoline engine.

A. less expensive

66. The fuel injection process in diesel engines starts when the piston_______ during the first part of power stroke.

B. before TDC

67. In diesel engine, combustion process during combustion occurs during

B. constant pressure process

68. The Otto and Diesel cycle differs during

D. combustion process

69. A measure of performance for any power cycle is its

B. thermal efficiency

70. Is the ratio of cylinder volumes after and before the combustion process.

C. cut-off ratio

71. The thermal efficiency of Otto cycle is always ____ the thermal efficiency of Diesel cycle when both cycle operates in the same compression ratio.

A. greater than

73. If the cutoff ratio is decreases, the efficiency of diesel cycle

A. increases

74. The diesel engines also burn the fuel more completely since they usually operate _____ than spark ignition engines.

C. lower revolutions per minute

75. Thermal efficiencies of diesel engines range from about

D. 35 to 40%

A. higher efficiency and lower fuel costs

77. A diesel engine can be built as much as _______ at 122 rpm.

C. 25,200 hp

78. A better approach would be to model the combustion process in both gasoline and diesel engines as a combination of two heat transfer process. This process is known as

D. Dual cycle

79. In dual cycle, the heat is added during constant volume and_____ process.

B. constant pressure

80. ______ is the process during which heat is transferred to a thermal energy storage device.

B. regeneration

81. The regenerator is a device that borrows ______ from the working fluid during one part of the cycle and pays it back during another part of the cycle.

B. Energy

82. In Stirling cycle, regeneration process works during______ process.

A. constant volume

83. In Ericsson cycle, the regeneration process occurs during _______ process

C. constant pressure

84. Invented Stirling engine is _______ very heavy and complicated.

D. Robert Stirling

85. Both the Stirling and Ericsson cycles are totally reversible as is the

A. Carnot cycle

86._______ have the same efficiency when operating the same temperature limits.

C. Stirling, Ericsson and Carnot cycles

87. Both the Stirling and Ericsson cycles are

B. external combustion engines

88. Are two gasses commonly employed in Stirling and Ericsson cycles

A. Hydrogen and Helium

89. Advantage of Stirling and Ericsson cycle:

D. All of these

90. In Stirling cycle, Regeneration can

B. increase efficiency

91. Brayton cycle is invented by

D. George Brayton

92. Gas turbines usually operates on an

B. open cycle

93. In gas turbine, the gas is expanded to the

A. vacuum pressure

94. Brayton cycle is made up of_________internally reversible process.

D. four

95. In Brayton cycle, the, ________during constant pressure process

B. heat is transferred

96. The thermal efficiency of an ideal Brayton cycle depends on

D. pressure ratio of the gas turbine and specific heat ratio

97. The highest Temperature of gas turbine cycle occurs at the end of

C. combustion process

98. For a fixed turbine inlet temperature, the net work output per cycle increases with the pressure ratio, reaches the maximum, and then starts to

B. decrease

99. In most common designs of Gas turbines, the pressure ratio ranges from

B. 11 to 16

100. In gas turbines, an air-fuel mass ratio of ______ is not uncommon

D. 50 or above