This is the Multiple Choice Questions Part 2 of the Series in Power Plant Engineering as one of the Mechanical Engineering topic. In Preparation for the ME Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Exam Questions in Mechanical Engineering field, Mechanical Engineering Books, Journals and other ME References. I assume you are looking for a reviewer that will help you achieve your goal to become a License Mechanical Engineer very soon. Yes, you are in the right place to make your dream come true. Make sure to familiarize each and every questions to increase the chance of passing the Mechanical Board Examination.

#### MCQ Topic Outline included in ME Board Exam Syllabi

- MCQ in Power Plant Elements
- MCQ in Power Plant Design
- MCQ in Industrial Plant Engineering
- MCQ in Industrial Plant Design
- MCQ in Refrigeration Engineering and its Applications
- MCQ in Air Conditioning

#### Continue Practice Exam Test Questions Part 2 of the Series

⇐ MCQ in Power Plant Engineering Part 1 | ME Board Exam

**Choose the letter of the best answer in each questions.**

51. Steam at 2 MPa and 250°C in a rigid cylinder is cooled until the quality is 30%. Find the heat rejected from the cylinder.

@ 2 Mpa and 250°C: υ = 0.11144 m^{3}/kg u = 2679.6 kJ/kg

@ 2 Mpa, (saturated): υf = 0.0011767 m^{3}/kg υg = 0.09963 m^{3}/kg

uf = 906.44kJ/kg ug = 1693.8 kJ/kg

A. -423.23 kJ/kg

B. -926.26 kJ/kg

C. -1265.02 kJ/kg

D. 1082.34 kJ/kg

Answer: **Option C**

Explanation:

52. At 1.3 MPa, a mixture of steam and water has an entropy of 3 kJ/kg-K, Find the enthalpy of the mixture.

@ 1.3MPa: sf = 2.2515 kJ/kg-K sg = 6.4952 kJ/kg-K

hf = 814.93 kJ/kg hfg = 1972.7 kJ/kg

A. 1627.71 kJ/kg

B. 1533.33 kJ/kg

C. 1234.45 kJ/kg

D. 1162.40 kJ/kg

Answer: **Option D**

Explanation:

53. A mixture with 70% quality at 500 kPa is heated isothermally until its pressure is 300 kPa. Find the heat added during the process.

@ 600 kPa: sf = 1.8607 kJ/kg-K sfg = 4.9606 kJ/kg-K

@ 300 kPa and 151.86°C: s = 7.0888 kJ/kg-K

A. 745.92 kJ/kg

B. 535.16 kJ/kg

C. 982.44 kJ/kg

D. 765.34 kJ/kg

Answer: **Option A**

Explanation:

54. A tank contains exactly one kilogram of water consisting of liquid and vapor in equilibrium at 1 MPa. If the liquid contains one-third and the remaining is vapor of the volume of the tank, what is the enthalpy of the contents of the tank?

@ 1MPa: υf = 0.0011273 m^{3}/kg υfg = 0.19444 m^{3}/kg

hf = 762.81 kJ/kg hfg = 2015.3 kJ/kg

A. 644.40 kJ/kg

B. 774.40 kJ/kg

C. 785.92 kJ/kg

D. 435.29 kJ/kg

Answer: **Option C**

Explanation:

55. Water substance at 70 bar and 65°C enters a boiler tube of constant inside diameter of 25 mm. The water leaves the boiler tube at 50 bar and 700 K at velocity of 150 m/s. Calculate the inlet velocity (m/s).

From steam tables:

@ 70 bar (7 Mpa) and 65°C: υ1 = 0.001017 m^{3}/kg

@ 50 bar (5 Mpa) and 700 K (427°C): υ2 = 0.06081 m^{3}/kg

A. 1.56

B. 2.51

C. 1.672

D. 3.230

Answer: **Option B**

Explanation:

56. Water substance at 70 bar and 65°C enters a boiler tube of constant inside diameter of 35 mm. The water leaves the boiler tube at 50 bar and 700 K at velocity of 150 m/s. Calculate the inlet volume flow (liters/s).

From steam tables:

@ 70 bar (7 Mpa) and 65°C: υ1 = 0.001017 m^{3}/kg

@ 50 bar (5 Mpa) and 700 K (427°C): υ2 = 0.06081 m^{3}/kg

A. 0.821

B. 1.261

C. 0.344

D. 1.609

Answer: **Option D**

Explanation:

57. Steam leaves an industrial boiler at 827.4 kPa and 171.6°C. A portion of the steam is passed through a throttling calorimeter and is exhausted to the atmosphere when the calorimeter pressure is 101.4 kPa. How much moisture is leaving the boiler container if the temperature of the steam at the calorimeter is 115.6°C?

@ 827.4 kPa and 171.6°C: hf = 727.25 kJ/kg hfg = 2043.2 kJ/kg

@ 101.4 kPa and 115.6°C: h2 = 2707.6 kJ/kg

A. 3.78%

B. 3.08%

C. 4.56%

D. 2.34%

Answer: **Option B**

Explanation:

58. A throttling calorimeter is connected to a desuperheated steam line supplying steam to the auxiliary feed pump on a ship. The line pressure measures 2.5 MPa. The calorimeter pressure is 110 kPa at 150°C. Determine the entropy of the steam line.

@ 110 kPa and 150°C: h2 = 2775.6 kJ/kg

@ 2.5 MPa: hf = 962.11 kJ/kg hfg = 1841 kJ/kg

sf = 2.5547 kJ/kg-K sfg = 3.7028 kJ/kg-K

A. 6.8 kJ/kg-K

B. 6.2 kJ/kg-K

C. 6.6 kJ/kg-K

D. 7.5 kJ/kg-K

Answer: **Option B**

Explanation:

59. Atmospheric pressure boils at 212°F. At the vacuum pressure at 24 in Hg, the temperature is 142°F. Find the boiling temperature when the pressure is increased by 40 psia from atmospheric.

A. 449.42°F

B. 536.34°F

C. 479.13°F

D. 263.45°F

Answer: **Option A**

Explanation:

60. A certain coal has the following ultimate analysis:

C = 69% N2 = 5% H = 2.5% S =7%

Determine the amount of oxygen if the heating value of fuel is 26,961.45 kJ/kg.

A. 1.5%

B. 2.5%

C. 3.5%

D. 4.5%

Answer: **Option C**

Explanation:

61. A diesel engine consumed 945 liters of fuel per day at 35°C. If the fuel was purchased at 15.6°C and 30°API at P29.00/li. Determine the cost of fuel to operate the engine per day.

A. P5,677.50

B. P4,677.50

C. P48,088.90

D. P27,127.76

Answer: **Option D**

Explanation:

62. A cylindrical tank 4 m long and 3 m diameter is used for oil storage. How many days can the tank supply the engine having 27°API with fuel consumption of 60 kg/hr?

A. 17.53

B. 5.84

C. 12.84

D. 19.84

Answer: **Option A**

Explanation:

63. A logging firm in Isabella operates a Diesel Electric Plant to supply its electric energy requirements. During a 2 hour period, the plant consumed 250 gallons of fuel at 80°F and produced 2900 kW-hrs. Industrial fuel is used at 30°API and was purchased at P30/li at 60°F. Determine the overall thermal efficiency of the plant.

A. 26.08%

B. 34.23%

C. 28.00%

D. 18.46%

Answer: **Option C**

Explanation:

64. The dry exhaust gas from the oil engine has the following gravimetric analysis:

CO_{2} = 21.6% O_{2} = 4.2% N = 74.2%

Specific heats at constant pressure for each component of the exhaust gas in kCal/kg-°C are:

CO_{2} = 0.203 O_{2} = 0.219 N = 0.248

Calculate the specific gravity if the molecular weight of air is 28.97 kg/kg-mol.

A. 0.981

B. 1.244

C. 1.055

D. 0.542

Answer: **Option C**

Explanation:

65. A bituminous coal has the following composition:

C = 71.5% H = 5.0% O = 7.0% N = 1.3% S = 3% Ash = 7.6% W = 3.4%

Determine the theoretical weight of Nitrogen in lb./lb. of coal.

A. 2.870

B. 7.526

C. 2.274

D. 6.233

Answer: **Option B**

Explanation:

66. A gaseous fuel mixture has a molal analysis:

H_{2} = 14% CH_{4} = 3% CO = 27% O_{2} = 0.6% CO_{2} = 4.5% N_{2} = 50.9%

Determine the air-fuel ratio for complete combustion on molal basis.

A. 2.130

B. 3.230

C. 1.233

D. 1.130

Answer: **Option C**

Explanation:

67. A volumetric analysis of a gas mixture is a follows:

CO_{2}: 12% O_{2}: 4% N_{2}: 80% CO: 4%

What percentage of CO2 on a mass basis?

A. 17.55%

B. 15.55%

C. 12.73%

D. 19.73%

Answer: **Option A**

Explanation:

68. The following coal has the following ultimate analysis by weight:

C = 70.5% H_{2} = 4.5% O_{2} = 6.0% N_{2} = 1.0% S = 3.0% Ash = 11% Moisture = 4%

A stocker fired boiler of 195,000 kg/hr. steaming capacity uses this coal as fuel. Calculate volume of air in m^{3}/hr. with air at 60°F and 14.7 air pressure if the boiler efficiency is 70% and FE = 1.10.

A. 234,019 m^{3}/hr.

B. 215,830 m^{3}/hr.

C. 213,830 m^{3}/hr.

D. 264,830 m^{3}/hr.

Answer: **Option A**

Explanation:

69. 23.5 kg of steam per second at 5 MPa and 400°C is produced by a steam generator. The feedwater enters the economizer at 145°C and leaves at 205°C. The steam leaves the boiler drum with a quality of 98%. The unit consumes 3 kg of coal per second as received having value of 25,102 kJ/kg. What would be the overall efficiency of the unit in percent?

Steam properties:

@ 5 MPa and 400°C: h = 3195.7 kJ/kg

@ 5 MPa: hf = 1154.23 kJ/kg hfg = 1640.1 kJ/kg

@ 205°C: hf = 875.04 kJ/kg

@ At 145°C: hf = 610.63 kJ/kg

A. 65.72

B. 80.67

C. 88.28

D. 78.82

Answer: **Option B**

Explanation:

70. In a Rankine cycle steam enters the turbine at 2.5 MPa (enthalpies & entropies given) and condenser of 50 kPa (properties given), what is the thermal efficiency of the cycle?

@ 2.5 MPa: hg = 2803.1 kJ/kg sg = 6.2575 kJ/kg-K

@ 50 kPa: sf = 1.0910 kJ/kg-K sfg = 6.5029 kJ/kg-K

hf = 340.49 kJ/kg hfg = 2305.4 kJ/kg

υf = 0.00103 m^{3}/kg

A. 25.55%

B. 45.23%

C. 34.23%

D. 12.34%

Answer: **Option A**

Explanation:

71. A thermal power plant generates 5 MW and the heat generated by fuel is 13,000 kJ/s. If the thermal efficiency is 36.15%, find the power needed for the auxiliaries.

A. 310 kW

B. 300 kW

C. 400 kW

D. 350 kW

Answer: **Option B**

Explanation:

72. A superheat steam Rankine cycle has turbine inlet conditions of 17.5 MPa and 530°C expands in a turbine to 0.007 MPa. The turbine and pump polytropic efficiencies are 0.85 and 0.75 respectively. Pressure losses between the pump and turbine inlet are 1.5 MPa. What should be the pump work in kJ/kg?

A. 17.34

B. 27.32

C. 25.32

D. 47.33

Answer: **Option C**

Explanation:

73. In an open feedwater heater for a steam plant, saturated steam at 7 bar is mixed with subcooled liquid at 7 bar and 25°C. Just enough steam is supplied to ensure that the mixed steam leaving the heater will be saturated liquid at 7 bar when heater efficiency is 95%. Calculate the mass flow rate of the subcooled liquid if steam flow rate is 0.865 kg/s.

Steam properties:

@ 7 bar, saturated vapor: hg = 2763.5 kJ/kg

@ 7 bar and 25°C: hf = 105.5 kJ/kg

@ 7 bar, saturated liquid: hf = 697.22 kJ/kg

A. 2.725 kg/s

B. 3.356 kg/s

C. 2.869 kg/s

D. 3.948 kg/s

Answer: **Option C**

Explanation:

74. A steam condenser receives 10 kg/s of steam with an enthalpy of 2770 kJ/kg. Steam condenses and leaves with an enthalpy of 160 kJ/kg. Cooling water passes through the condenser with temperature increases from 13°C to 24°C. Calculate the water flow rate in kg/s.

A. 583

B. 567

C. 523

D. 528

Answer: **Option B**

Explanation:

75. Steam expands adiabatically in a turbine from 2000 kPa, 400°C to 400 kPa, 250°C. What is the effectiveness of the process in percent assuming an atmospheric pressure of 18°C? Neglect changes in kinetic and potential energy.

Steam properties:

@ 2000 kPa and 400°C: h = 3247.6 kJ/kg s = 7.1271kJ/kg-K

@ 400 kPa and 250°C: h = 2964.2 kJ/kg s = 7.3789 kJ/kg-K

A. 82

B. 84

C. 79.60

D. 79.46

Answer: **Option D**

Explanation:

76. A heat exchanger was installed purposely to cool 0.50 kg of gas per second. Molecular weight is 32 and k = 1.32. The gas is cooled from 150°C to 80°C. Water is available at the rate of 0.30 kg/s and at a temperature of 15°C. Calculate the exit temperature of the water in °C.

A. 44.86

B. 42.86

C. 46.45

D. 40.34

Answer: **Option A**

Explanation:

77. A 350 mm x 450 mm steam engine running at 280 rpm has a clearance steam condition of 2 MPa and 230°C and exits at 0.1 MPa. The steam consumption is 2000 kg/hr and mechanical efficiency is 85%. If indicated mean effective pressure is 600 kPa, determine brake thermal efficiency.

@ 2 MPa and 230°C: h1 = 2849.6 kJ/kg s1 = 6.4423 kJ/kg-K

@ 0.1 MPa: sf = 1.3026 kJ/kg-K hf = 417.46kJ/kg sfg = 6.0568 kJ/kg-K

hfg = 2258 kJ/kg hf2 = 417.46 kJ/kg

A. 23.34%

B. 15.25%

C. 14.16%

D. 27.34%

Answer: **Option B**

Explanation:

78. A steam turbine receives 5,000 kg/hr. of steam at 5 MPa and 400°C and velocity of 30 m/s. It leaves the turbine at 0.006 MPa and 85% quality and velocity of 15 m/s. Radiation loss is 10,000 kJ/hr. Find the kW developed.

@5 MPa and 400°C: h1 = 3195.7 kJ/kg s1 = 6.6459 kJ/kg-K

@ 0.006 Mpa: hf = 151.53 kJ/kg hfg = 2415.9 kJ/kg

A. 1273.29

B. 2173.29

C. 1373.60

D. 7231.29

Answer: **Option C**

Explanation:

79. A steam turbine with 85% stage efficiency receives steam at 7 MPa and 550°C and exhausts at 20 kPa. Determine the turbine work.

@ 7 MPa and 550°C: h1 = 3530.9 kJ/kg s1 = 6.9486 kJ/kg-K

@ 20 kPa (0.020 MPa): sf = 0.8320 kJ/kg-K hf = 251.40 kJ/kg

sfg = 7.0766 kJ/kg-K hfg = 2358.3 kJ/kg

A. 1,117 kJ/kg

B. 1,132 kJ/kg

C. 1,123.34 kJ/kg

D. 1,054.95 kJ/kg

Answer: **Option D**

Explanation:

80. A steam turbine with 80% stage efficiency receives steam at 7 MPa and 550°C and exhausts at 20 kPa. Determine the quality at exhaust.

@ 7 MPa and 550°C: h1 = 3530.9 kJ/kg s1 = 6.9486 kJ/kg-K

@ 20 kPa (0.020 MPa): sf = 0.8320 kJ/kg-K hf = 251.40 kJ/kg

sfg = 7.0766 kJ/kg-K hfg = 2358.3 kJ/kg

A. 96.96%

B. 76.34%

C. 82.34%

D. 91.69%

Answer: **Option A**

Explanation:

81. An 18,000 kW geothermal plant has a generator efficiency of 90% and 80% respectively. If the quality after throttling is 20% and each well discharges 400,000 kg/hr, determine the number of wells required to produce if the change of enthalpy at entrance and exit of turbine is 500 kJ/kg.

A. 4 wells

B. 2 wells

C. 6 wells

D. 8 wells

Answer: **Option B**

Explanation:

82. A liquid dominated geothermal plant with a single flash separator receives water at 204°C. The separator pressure is 1.04 MPa. A direct contact condenser operates at 0.034 MPa. The turbine has a polytropic efficiency of 0.75. For cycle output of 60 MW, what is the mass flow rate of the well water in kg/s?

@ 204°C: hf = 870.51 kJ/kg

@ 1.04 MPa: hf = 770.38 kJ/kg hfg = 2009.2 kJ/kg hg = 2779.6 kJ/kg sg = 6.5729 kJ/kg-K

@ 0.034 MPa: hf = 301.40 kJ/kg hfg = 2328.8 kJ/kg sf = 0.09793 kJ/kg-K sfg = 6.7463 kJ/kg-K

A. 2,933

B. 2,100

C. 1,860

D. 2,444

Answer: **Option A**

Explanation:

83. An engine-generator rated 9000 kVA at 80% power factor, 3 phase, 4160 V has an efficiency of 90%. If the overall plant efficiency is 28%, what is the heat generated by the fuel?

A. 18,800 kW

B. 28,800 kW

C. 7,500 kW

D. 25,714 kW

Answer: **Option D**

Explanation:

84. The indicated thermal efficiency of a two stroke diesel engine is 60%. If friction power is 15% of heat generated, determine the brake thermal efficiency of the engine.

A. 43%

B. 45%

C. 36%

D. 37%

Answer: **Option B**

Explanation:

85. A 305 mm x 457 mm four stroke single acting diesel engine is rated at 150 kW at 260 rpm. Fuel consumption at rated load is 0.56 kg/kW-hr with a heating value of 43,912 kJ/kg. Calculate the break thermal efficiency.

A. 10.53%

B. 27.45%

C. 14.64%

D. 18.23%

Answer: **Option C**

Explanation:

86. A waste heat recovery boiler produces 4.8 MPa (dry saturated) steam from 104°C feedwater. The boiler receives energy from 7 kg/s of 954°C dry air. After passing through a waste heat boiler, the temperature of the air has been reduced to 343°C. How much steam in kg is produced per second? Note: @ 4.80 MPa dry saturated, h = 2796 kJ/kg.

A. 1.30

B. 0.92

C. 1.81

D. 3.43

Answer: **Option C**

Explanation:

87. A diesel electric power plant supplies energy for Meralco. During a 24-hour period, the plant consumed 240 gallons of fuel at 28°C and produced 3930 kW-hr. Industrial fuel used is 28°API and was purchased at P30 per liter at 15.6°C. What is the cost of fuel to produce one kW-hr?

A. P6.87

B. P1.10

C. P41.07

D. P5.00

Answer: **Option A**

Explanation:

88. In a gas unit, air enters the combustion chamber at 550 kPa, 227°C and 43 m/s. The products of combustion leave the combustor at 511 kPa, 1004°C and 180 m/s. Liquid fuel enters with a heating value of 43,000 kJ/kg. For fuel-air ratio of 0.0229, what is the combustor efficiency in percent?

A. 70.38%

B. 79.38%

C. 75.38%

D. 82.38%

Answer: **Option C**

Explanation:

89. The specific speed of turbine is 85 rpm and running at 450 rpm. If the head is 20 m and generator efficiency is 90%, what is the maximum power delivered by the generator?

A. 450.51 kW

B. 354.52 kW

C. 650.53 kW

D. 835.57 kW

Answer: **Option D**

Explanation:

90. In Francis turbine, the pressure gage leading to the turbine casing reads 380 kPa. The velocity of water entering the turbine is 8 m/s. If net head of the turbine is 45 m, find the distance from the center of the spiral casing to the tailrace.

A. 3.0 m

B. 3.5 m

C. 4.0 m

D. 4.5 m

Answer: **Option A**

Explanation:

91. A turbine has a mechanical efficiency of 93%, volumetric efficiency of 95% and total efficiency of 82%. If the effective head is 40 m, find the total head.

A. 48.72 m

B. 40.72 m

C. 36.22 m

D. 34.72 m

Answer: **Option C**

Explanation:

92. A Pelton type turbine has 25 m head friction loss of 4.5 m. The coefficient of friction head loss (Morse) is 0.00093 and penstock length of 80 m. What is the penstock diameter?

A. 1,355.73 mm

B. 3476.12 mm

C. 6771.23 mm

D. 1686.73 mm

Answer: **Option A**

Explanation:

93. In a 9,000 kW hydro-electric plant, the overall efficiency is 88% and the actual power received by the costumer is 110,000 kW-hrs for that day. What is the secondary power that this plant could deliver during the entire day?

A. 58,960 kW-hrs.

B. 80,080 kW-hrs.

C. 65,960 kW-hrs.

D. 70,960 kW-hrs.

Answer: **Option B**

Explanation:

94. A Pelton type turbine was installed 30 m below the head gate of the penstock. The head loss due to friction is 12 percent of the given elevation. The length of the penstock is 100 m and the coefficient of friction is 0.00093. Determine the power output in kW. (Use Morse equation).

A. 22,273

B. 23,234

C. 32,345

D. 34,452

Answer: **Option D**

Explanation:

95. Water flows steadily with a velocity of 3.05 m/s in a horizontal pipe having a diameter of 25.24 cm. At one section of the pipe, the temperature and pressure of the water are 21°C and 689.3 kPa respectively. At a distance of 304.8 m downstream, the pressure is 516.9 kPa. What is the friction factor?

A. 0.134

B. 0.0050

C. 0.0307

D. 0.641

Answer: **Option C**

Explanation:

96. A hydro-electric plant having 30 sq. km reservoir area and 100 m head is used to generate power. The energy utilized by the consumers whose load is connected to the power plant during a five-hour period is 13.5 x 10^{6} kWh. The overall generation efficiency is 75%. Find the fall in the height of water in the reservoir after the 5-hour period.

A. 5.13 m

B. 1.32 m

C. 3.21 m

D. 2.20 m

Answer: **Option D**

Explanation:

97. The gas density of chimney is 0.75 kg/m^{3} and air density of 1.15 kg/m^{3}. Find the driving pressure if the height of the chimney is 63.71 m.

A. 0.15 kPa

B. 0.25 kPa

C. 0.35 kPa

D. 0.45 kPa

Answer: **Option B**

Explanation:

98. The actual velocity of gas entering in a chimney is 8 m/s. The gas temperature is 25°C with a gas constant of 0.287 kJ/kg-K. Determine the gas pressure for a mass of a gas is 50,000 kg/hr. and chimney diameter of 1.39 m.

A. 95 kPa

B. 98 kPa

C. 101 kPa

D. 92 kPa

Answer: **Option B**

Explanation:

99. A steam generator with economizer and air heater has an overall draft loss of 25.78 cm of water. If the stack gases are at 177°C and if the atmosphere is at 101.3 kPa and 26°C, what theoretical height of stack in meters is needed when no draft fan is used? Assume that the gas constant for the flue gases is the same as that for air.

A. 611.10

B. 631.10

C. 651.10

D. 671.10

Answer: **Option C**

Explanation:

100. A foundation measures 12 ft. x 14 ft. x 16 ft. Find the number of sacks of cement needed for a 1:2:4 mixture.

A. 302

B. 404

C. 356

D. 598

Answer: **Option D**

Explanation:

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