College of Engineering Education – Competency Appraisal Course
Mechanical Engineering
2nd Semester SY 2022-2023
Comprehensive Exam
POWER AND INDUSTRIAL PLANT ENGINEERING:
1. How do you call the water vapor content of air?
A. moisture
C.
B. humidity
D.
dew
vapor
2. Which of the following dehumidifier is often used to reheat the air after moisture is
removed?
A. evaporator
C. condenser
B. chiller
D. compressor
3. Which of the following refrigerant is added sometimes to other refrigerant to improve
oil circulation?
A. R-117
C. R-170 (ethane)
B. R-777
D. R-270
4. A refrigeration that deals with producing temperature of -157°C or lower.
A. low temperature refrigeration
C. absolute zero refrigeration
B. extremely low refrigeration
D. cryogenics
5.
Which of the following refrigerants is popular in the industrial refrigerating system;
also popular absorption system of refrigerant.
A. R-717
C. R-611
B. R-600
D. R-504
6.
Which of
A.
B.
C.
D.
7.
Oxygen is approximately what percent by weight in the atmosphere?
A. 23%
C. 77%
B. 27%
D. 73%
8.
Air conditioning is the process of:
A. keeping a place cool
B. removing heat from specific area
C. maintaining the air at a required temperature and humidity
D. A or C
9.
the following is a function of air conditioning?
temperature and humidity control
air filtering, cleaning, and purification
air movement and circulation
all of these
In an air conditioning system, before the air is circulated to the required area, it
is:
A. cooled
C. dehumidified
B. filtered
D. all of the above
10. The temperature at which water vapor in the atmosphere begins to condense is known as
the:
A. vapor point
C. moisture point
B. dew point
D. none of the above
11. Saturation temperature is the same as:
A. dew point
B. vapor temperature
C.
D.
steam temperature
humidity
12. When the bypass factor is B, the coil efficiency for sensible cooling of air is equal
to:
A. 1 + B
C. 1 – B/B
B. 1 – B
D. 1 + B/B
13. Which of the following
conditioning unit?
A. temperature
B. air purity
variables is most often maintained by a commercial airC.
D.
air motion
humidity
14. Which of the following is not a process characteristic controlled in long term storage
chambers?
A. temperature
C. humidity
B. air velocity
D. air purity
15. The entropy of a process in which an ideal gas experience a reduction in its internal
energy ________.
A. increases
C. remains the same
B. decreases
D. constant
College of Engineering Education – Competency Appraisal Course
Mechanical Engineering
2nd Semester SY 2022-2023
Comprehensive Exam
16. As the volume of a gas decreases, its specific gas constant _________.
A. increases
C. remains the same
B. decreases
D. decrease by 10%
17. As a gas is heated in an isometric process, its volume _________.
A. increases
C. remains the same
B. decreases
D. decrease by 20%
18. A gas is cooled in an isobaric process, its volume _________.
A. increases
C. remains the same
B. decreases
D. constant
19. As a gas is heated in an isothermal process, its volume _________.
A. increases
C. remains the same
B. decreases
D. constant
20. As the pressure of a vapor increases, the amount of work it can do increases and its
enthalpy _________.
A. increases
C. remains the same
B. decreases
D. constant
21. As a liquid changes phase to a vapor, its enthalpy ________.
A. increases
C. remains the same
B. decreases
D. constant
22. As a liquid changes phase to a solid, its entropy ________.
A. increases
C. remains the same
B. decreases
D. constant
23. The change in kinetic energy of a gas process ________ as the change in temperature of
the process path increases.
A. increases
C. remains the same
B. decreases
D. none of the above
24. A residential dehumidifier is an application belonging to the ___________ category.
A. domestic refrigeration
C. domestic air-conditioning
B. commercial air-conditioning
D. industrial refrigeration
25. Providing clean, filtered air for trouble free operation of equipment
instrumentation is a function of ___________.
A. industrial refrigeration
C. commercial air-conditioning
B. industrial air-conditioning
D. comfort air-conditioning
and
26. Which of the following is not a form of moisture loss from frozen food products?
A. sublimation
C. freezer burn
B. spoilage
D. dehydration
27. Heat transfer that
process.
A. air blast
B. immersion
occurs
primarily
by
conduction
C.
D.
is
used
for
________
freezing
indirect contact
all of the above
28. Determine the heat extracted from 2000kg of water from 25 °C to ice at -10 °C.
A. 621,150 kJ
C. 821,150 kJ
B. 721,150 kJ
D. 921,150 kJ
29. What is the specific volume of an air-vapor mixture at 30 °C and a relative humidity
of 45 °C at 101.325 kPa.
A. 0.578 m3 /kg
C. 0.875 m3 /kg
B. 0.785 m3 /kg
D. 0.758 m3 /kg
30. An ideal dual combustion cycle operates on 0.65 kg of air. At the beginning of
compression, the air is at 100 kPa, 45 °C. Determine the volume at the end of
compression if net work is 300 kJ and the mean effective pressure is 700 kPa.
A. 0.16 m3
C. 0.12 m3
3
B. 0.26 m
D. 0.22 m3
31. A four cylinder, 4 stroke cycle, 20 cm x 25 cm x 550 rpm diesel engine has a mean
effective pressure of 150 psi. Calculate the brake power in kW if engine efficiency is
88%.
A. 131 kW
C. 141 kW
B. 138 kW
D. 148 kW
32. What is the thermal efficiency of an air-standard Brayton cycle if the pressure ratio
is 10.
A. 42.44 %
C. 45.36 %
B. 50.16 %
D. 48.21 %
College of Engineering Education – Competency Appraisal Course
Mechanical Engineering
2nd Semester SY 2022-2023
Comprehensive Exam
33. What is the heating surface area of a water tube boiler if the equivalent rated boiler
horsepower is 200?
A. 198 m2
C. 450 m2
B. 206 m2
D. 182 m2
34. The heating surface area of a fire tube boiler is 400 m2 .What is the equivalent rated
boiler horsepower?
A. 363.64 Hp
C. 256.78 Hp
B. 435.72 Hp
D. 135.72 Hp
35. 31. A hydroelectric generating station is supplied from a reservoir of capacity
6,000,000m3 at a head of 170 m. Assume hydraulic efficiency of 80% and electrical
efficiency of 90%. The fall in the reservoir level after a load of 15MW has been
supplied for 3 hrs, if the area of the reservoir is 2.5 km2 is closest to:
A. 5.98 cm
C. 5.39 cm
B. 4.32 cm
D. 4.83 cm
36. A daily load curve which exhibited at 15 minute peak of 150,000 kW is drawn to scales
of 1 cm = 3 hrs and 1 cm = 10, 000 kW. The area under the curve is measured by a
planimeter and to be 60 cm2 . What is the load based on the 15 minute peak?
A. 0.50
C. 0.55
B. 0.75
D. 0.65
37. A central station has an annual factors as follows: Load factor 58.5 %, Capacity
factor 40.9 %, use factor 45.2 %. The reversed carried over and above the peak load is
8,900 kW. Find the no. of hrs per year not in service.
A. 873.33 hrs
C. 783.33 hrs
B. 833.37 hrs
D. 733.38 hrs
38. A pump has an efficiency of 65%. It is driven by a 0.75 horsepower motor. The pump
produces a pressure rise of 120 Pa in water. What is the required flow rate?
A. 3.03 m3/s
C. 4.55 m3/s
B. 4.04 m3/s
D. 4.66 m3/s
39. The pressure drop across the turbine is 30 psi. The flow rate is 60 gallons per minute.
Calculate the power output of the turbine.
A. 0.41 Hp
C. 2.54 Hp
B. 1.05 Hp
D. 6.30 Hp
40. Steam at 1000 lbf/ft2 pressure and 300°R has a specific volume of 6.5 ft3 /lbm and a
specific enthalpy of 9800 lbf-ft/lbm. Find the internal energy per pound mass of steam.
A. 2500 lbf-ft/lbm
C. 5400 lbf-ft/lbm
B. 3300 lbf-ft/lbm
D. 6900 lbf-ft/lbm
41. A gas is heated at a constant temperature of 550°C until the entropy increases by 3.00
x 106 J/K. How much heat is added?
A. 2.5 GJ
C. 2.7 GJ
B. 2.9 GJ
D. 3.1 GJ
42. What would be
coefficient for
A. 2500
B. 4125
the resistance of the scale deposit if the overall
a tube reduced from 1,500 W/m2-K to 1,100 W/m2-K?
W/m2-K
C. 3500 W/m2-K
W/m2-K
D. 5550 W/m2-K
heat
transfer
43. A two meter I. D. pipe is flowing half full. What is the hydraulic radius?
A. 1.00 m
C. 1.50 m
B. 0.50 m
D. 1.75 m
44. A large municipal power plant produces 1,000 MW of power. The overall plant efficiency
is 32%. Coal with heating value of 24 MJ/kg is used to heat the boilers. How much coal
is burned each day?
A. 10,500 metric tons
C. 12,000 metric tons
B. 11,250 metric tons
D. 12,500 metric tons
45. A centrifugal pump pumps water at the rate of 1000 L/min against a head of 10 m. What
is the power requirement?
A. 1.59 kW
C. 1.98 kW
B. 1.63 kW
D. 1.07 kW
46. An engine operating on a Carnot cycle between temperatures of 500 °C and 30 °C produces
50 kJ of work. What change in entropy occurs during the heat rejection process?
A. -0.1064 kJ/K
C. 0.1064 kJ/K
B. -0.1340 kJ/K
D. 0.1340 kJ/K
47. In an Otto cycle, the initial volume of 50 cc of air and petrol mixture is compressed
to 10 cc isentropically with index of compression of 1.4. Calculate the thermal
efficiency.
College of Engineering Education – Competency Appraisal Course
Mechanical Engineering
2nd Semester SY 2022-2023
Comprehensive Exam
A.
B.
47.5 %
37.5 %
48. A reversed Carnot cycle absorbs heat at the
at 250 K and discharges it to the atmosphere
cycle.
A. 1 kW
B. 1.5 kW
C.
D.
45.7 %
57.7 %
rate of 1 kW from cold chamber maintained
at 300 K. Find the work required for the
C.
D.
0.2 kW
0.5 kW
49. A steel plate of 10 cm thickness and 1 sq. m area is maintained at temperature of 600
°C at one face and 100 °C on the other side. The thermal conductivity of steel is 20
W/m-K. Calculate the conduction heat transfer rate through this plate.
A. 100 kW
C. 200 kW
B. 300 kW
D. 400 kW
50. A hollow cylinder of 2 m length has inner and outer radius as 50 mm and 100 mm. The
inner surface and outer surface temperatures of this cylinder are 300 °C and 200 °C.
Determine the conduction heat transfer rate through this cylinder. Assume thermal
conductivity of this cylinder as 70 WA/m-K.
A. 126.9 kW
C. 192.6 kW
B. 196.2 kW
D. 162.9 kW
51. A coal fired steam power plant has to generate 1000 MW of electricity. The efficiency
of boiler , turbine and generator are 85%, 80% and 90% respectively. If the calorific
value of coal is 20 MJ/kg, calculate the fuel required for the plant per day.
A. 7059 tons
C. 8001 tons
B. 6543 tons
D. 6666 tons
52. A four stroke single cylinder IC engine develops 5 kW of brake power with mechanical
efficiency of 80 % running at 1500 rpm. If the mean effective pressure is 7 bar, find
the diameter of the cylinder assuming stroke and diameter are equal.
A. 97 mm
C. 79 mm
B. 58 mm
D. 85 mm
53. During complete stoichiometric combustion of 1 lb. mole of methane ( CH4 ) with air,
the number of lb. moles of Nitrogen other inert that pass through the combustion zone
is nearest to:
A. 0.79
C. 5.6
B. 3.9
D. 7.5
54. A power of 6 kW is supplied to the motor of a crane. The motor has an efficiency of
90%. With what constant speed does the crane lift an 800 lbf weight?
A. 0.09 cm/s
C. 0.98 cm/s
B. 0.32 cm/s
D. 1.52 cm/s
55. The heat of fusion of ice in calories per gram is approximately:
A. 335
C. 144
B. 80
D. 970
56. A pump produces a head of 30 feet. The volumetric flow rate is 10 gallon per minute.
The fluid pumped is oil with a specific gravity of 0.83. How much energy does the pump
consume in one hour?
A. 8.7 kJ
C. 168.9 kJ
B. 17.2 kJ
D. 203.6 kJ
57. A tank contains 80 ft3 of air at a pressure of
pressure and temperature decrease to 200 psi
decrease in internal energy?
A. 5507 Btu
C.
B. -4575 Btu
D.
350 psi. If the air cooled until its
and 70°F respectively, what is the
0
-5507 Btu
58. A Diesel Power Plant consumed 1 m3 of fuel with 30° API at 27 °C in 24 hrs. Calculate
the fuel rate in kg/hr.
A. 36.21
C. 39.42
B. 26.25
D. 29.34
59. A hollow sphere has an outside radius of 1m and is made of polystyrene foam with a
thickness of 1 cm. A heat source inside keeps the inner surface 5.20°C hotter than the
outside surface. How much power is produced by the heat source? The thermal
conductivity of polystyrene foam is 0.033 W/m-°C.
A. 200 W
C. 300 W
B. 216 W
D. 316 W
60. A cylindrical pipe with water flowing downward at 0.02 m3 /s having top diameter of
0.08, bottom diameter of 0.04 m and height of 1.5 m. Find the pressure between the
pipe?
A. 94.05 kPa
C. 124.07 kPa
B. 104.016 kPa
D. 134.10 kPa
College of Engineering Education – Competency Appraisal Course
Mechanical Engineering
2nd Semester SY 2022-2023
Comprehensive Exam
61. A fan manufacturer rates his fans at 152 mm water gage static pressure for 10 m3 of air
per second at 21°C, 1200 rpm and static efficiency of 69%. At what speed would these
fans operate to develop 130 mm water gage when the temperature is 316°C?
A. 1570 rpm
C. 1770 rpm
B. 1670 rpm
D. 1470 rpm
62. Helium is isothermally compressed from atmospheric and 528 °R. The compression ratio is
4. Calculate the change in entropy of the gas given that RHelium =0.4961 Btu/lbm-°R.
A. – 0.688 Btu/lbm-°R
C.
0.688 Btu/lbm-°R
B. – 2.760 Btu/lbm-°R
D.
2.760 Btu/lbm-°R
63. Calculate the work needed in order to compress air in an insulated cylinder from 0.20 m3
to 0.01 m3. Initial state at T1 = 68 °F and at atmospheric pressure.
A. 110.1 kJ
C.
115.7 kJ
B. 121.4 kJ
D.
113.4 kJ
64. Calculate the calorific value of coal which has the following analysis: Carbon 81%,
Hydrogen 5%, Oxygen 1.6%, Sulfur 1% and the remainder is ash content.
A. 32,135.45 kJ/kg
C.
32,457.45 kJ/kg
B. 33,688.35 kJ/kg
D.
12,456.45 kJ/kg
65. Methane
products
condensed
A.
B.
gas burn completely when supplied with 30% excess dry air.
are cooled at 32°C and 1 atm pressure. Determine the mass
per kg fuel.
1.302
.
C. 1.816
1.924
D. 1.614
The gaseous
of moisture
65. The temperature of the flame in a furnace is 1277°C and the temperature of its
surrounds is 277°C. Calculate the maximum theoretical quantity of heat energy radiated
per minute per square meter to the surrounding surface area.
A. 19,321.65 kJ
C. 17,321.65 kJ
B. 18,321.65 kJ
D. 16,321.65 kJ
66. An air-cooled condenser is to reject 70 kW of heat from a condensing refrigerant to
air. The condenser has an air side area of 210 m2 and a U value based on this area
0.037 kW/ m2 –K; it id supplied with 6.6 m3 /s of air which has density of 1.15 kg/ m3 .
If the condensing temperature is to be limited to 55°C, what is the maximum allowable
temperature of the inlet air?
A. 30.7°C
C. 50.7°C
B. 40.7°C
D. 20.7°C
67. Find the volume flow rate of water in L/s if the power developed under a head of 320 m
is 10,500 kW and the hydraulic efficiency is 85%.
A. 3,935
C. 3,271
B. 3,291
D. 3,721
68. Air taken the atmospheric at 100 kPaa and 21°C is delivered to the air receiver at 689
kPaa and 150°C by means of a water jacketed reciprocating compressor. The compressor
has a rated capacity of 360 m3 /hr free air. Determine the power required to compress
the air.
a. 23.24 kW
C. 33.24 kW
b. 25.26 kW
D. 35.26 kW
69. A pump delivers 500 gpm of water against a total head of 200 ft and operating at 1770
rpm. Changes have increased the total head to 375 ft. At what rpm should the pump be
operated to achieve the new head at the same efficiency.
A. 2800 rpm
C. 3434 rpm
B. 3600 rpm
D. 2424 rpm
70. A refrigerating system operates on the reversed Carnot Cycle. The higher temperature of
the refrigerant in the system is 120°F and the lower is 10°F. The capacity is 20 tons.
Neglect losses. Determine the network in Btu/min.
A. 936.21 Btu/min
C. 745.71 Btu/min
B. 457.57 Btu/min
D. 765.81 Btu/min
71. What is the specific volume of an air-vapor mixture at 30 °C and a relative humidity of
45 °C at 101.325 kPa.
A. 0.578 m3 /kg
C. 0.875 m3 /kg
College of Engineering Education – Competency Appraisal Course
Mechanical Engineering
2nd Semester SY 2022-2023
Comprehensive Exam
B. 0.785 m3 /kg
D. 0.758 m3 /kg
72. Compute the Humidity Ratio of air at 62% relative and 34 °C when the barometric
pressure is 101.325 kPa.
A. 0.021 kgvapor / kgdry-air
C. 0.041 kgvapor / kgdry-air
B. 0.031 kgvapor / kgdry-air
D. 0.051 kgvapor / kgdry-air
73. What would be the percentage of the over-all efficiency of a steam generator obtaining
an evaporation equivalent to 10.95 kg of water from and 100 °C per kg of coal
containing 34,064 kJ/kg heating value?
A. 73 %
C. 82 %
B. 74 %
D. 70 %
74. In Geothermal Power Plant, the mass flow rate of ground water is 400 kg/s and the
quality after throttling is 20 %. If the turbine power is 80 MW, what is the change in
enthalpy of steam at the inlet and outlet of the turbine?
A. 2500 kJ/kg
C. 1000 kJ/kg
B. 2500 kJ/kg
D. 1500 kJ/kg
75. A pelton turbine was installed 30 m below the head gate of the penstock. The head loss
due to friction is 15% of the given elevation. The length of the penstock is 80 m and
the coefficient of friction is 0.00093. Determine the power output in kW?
A. 14,292.74 kW
C. 19,242.74 kW
B. 12,492.74 KW
D. 17,442.74 kW
76. A reaction turbine develops 500 BHP. Flow through the
at 20 fps with a 100 ft pressure head. The elevation of
level is 10 ft. Find the effective head?
A. 130.2 ft
C. 110.2
B. 120.2 ft
D. 116.2
turbine is 50 cfs. Water enters
the turbine above the tailwater
ft
ft
77. The matching of scale and model and full-scale results for a fluid dynamic phenomena
with a free surface requires equality of:
A. Reynold’s number
C. Weber number
B. Froude number
D. Cauchy number
78. The matching of scale and model and full-scale results for a fluid dynamic phenomena
involving compressible fluids requires equality of:
A. Reynold’s number
C. Weber number
B. Froude number
D. Mach number
79. The matching of scale and model and full-scale prototype results for a fluid dynamic
phenomena involving surface tension requires equality of:
A. Reynold’s number
C. Weber number
B. Froude number
D. Mach number
80. The matching of scale and model and full-scale prototype results for a fluid dynamic
phenomena involving a fully submerged body requires equality of:
A. Reynold’s number
C. Weber number
B. Froude number
D. Mach number
81. The fact
fluids is
a.
b.
that there is no resistance to bodies moving through an ideal (non-viscous)
known as:
Reynold’s analogy
C. Newton’s second law
D’Alembert’s paradox
D. Second Law of Thermodynamics
82. The enthalpy of a fluid when it is brought to rest adiabatically.
A. Stagnation enthalpy
C.Absolute enthalpy
B. Static enthalpy
D. Adiabatic enthalpy
83. Through windage removes some of the solids, most must be removed by bleeding some of
the water off. This is known as:
A. range
C. drift
B. approach
D. bleed-off
84. The complement of bypass factor is:
A. saturation ratio
B. adiabatic cooling
C. coil efficiency
D. grand efficiency
85. The sensible heat ratio is a:
A. sensible slope
B. latent slope
C. geometric slope
D. psychrometric slope
86. Across the shock, stagnation temperature of an ideal gas:
A. increases
C. remains constant
B. decreases
D. proportional
College of Engineering Education – Competency Appraisal Course
Mechanical Engineering
2nd Semester SY 2022-2023
Comprehensive Exam
87. Find the approximate enthalpy of water at 180ºF.
A. 124 Btu/lb
C. 148 Btu/lb
B. 152 Btu/lb
D. 187 Btu/lb
88. Find the approximate enthalpy of the feedwater at 40ºC.
A. 167.48 kJ/kg
C. 186.34 kJ/kg
B. 176.34 kJ/kg
D. 152.34 kJ/kg
89. A 20 liter tank contains saturated liquid and saturated vapor at 200ºC. If the mass of
liquid is 5kg, find the moisture content of steam.
A. 28.90%
C. 32.34%
B. 23.40%
D. 97.82%
90. At 180ºC the entropy of the substance is 5.2 the quality of the substance is:
A. 34.23%
C. 56.34%
B. 68.83%
D. 87.56%
91. A 20 kg water at 50ºC saturated is vaporized until it is completely vaporized. Find the
volume of water vaporized in the tank.
A. 240.64 li
C. 562.32 li
B. 984.34 li
D. 220.04 li
92. A mixture of ideal gases has an apparent molecular weight of 36 kg/kg-mole and specific
enthalpy of 273.2 kJ/kg when the temperature is 127ºC. The specific internal energy of
this mixture in kJ/kg is:
A. 98.72
C. 181.8
B. 153.1
D. 273.2
93. A mixture composed of 70% Carbon Dioxide and 30% Helium by volume analysis is contained
at 1 MPa. What is the partial pressure in kPa of the Helium in this mixture?
A. 300
C. 600
B. 450
D. 700
94. Steam with specific volume of 0.09596 m3/kg undergoes a constant pressure process at
1.70 MPa until its specific volume 0.13796 m3/kg. What is the work done?
A. 71.4 kJ/kg
C. 82.78 kJ/kg
B. 67.1 kJ/kg
D. 97.23 kJ/kg
95. Steam with an enthalpy of 2843.5 kJ/kg undergoes a constant pressure process at 0.90
MPa until the steam becomes 2056.1 kJ/kg. What is the internal energy?
A. -703.2 kJ/kg
C. 564.3 kJ/kg
B. 703.2 kJ/kg
D. 984.4 kJ/kg
96. One kilogram of of steam at 260ºC and with an enthalpy of 1861 kJ/kg is confined in a
rigid container. Heat is applied until the steam becomes saturated. Determine the heat
added.
A. 770 kJ
C. 790 kJ
B. 828 kJ
D. 800 kJ
97. A tank contains 0.50 m3/kg of steam. Heat is transferred at constant volume until the
pressure reaches 100 kPa. Determine the final steam quality.
A. 23.34%
C. 29.47%
B. 45.32%
D. 39.45%
98. One kilogram of steam expands isentropically from 2.1 MPa and 374ºC to 93ºC. Find the
final quality.
A. 76.44%
C. 93.15%
B. 87.34%
D. 98.34%
99. A fuel is represented with C5H8 is burned with 40% excess air. If mass of fuel is 0.17
kg, find the mass of air needed.
A. 3.38 kg
C. 2.34 kg
B. 1.63 kg
D. 5.34 kg
100. A boiler burns fuel oil with 15% excess air. The fuel may be represented by C14H30.
Calculate the molal air-fuel ratio.
A. 14
C. 102.34
B. 117.69
D. 17.14
---------------------------------GOOD LUCK and GOD BLESS!!!------------------------------