MULTIPLE CHOICE

1. An engine operates on the cold air standard Otto cycle. The conditions at the start of the
compression are 100 kPa and 27°C. The heat added to the cycle is 1840 kJ/kg. Compression
ratio is 8. Find the mean effective pressure in kPa.
A. 1480
B. 1560
C. 1379
D. 1250
ANS: A

2. Calculate the ideal air standard cycle efficiency based on the Otto cycle for a Petrol engine
with a cylinder bore of 50 mm, a stroke of 75 mm, and a clearance volume of 21.3 cm 3.
A. 65.3 %
B. 56.3%
C. 36.5%
D. 63.5%
ANS: A

3. A four-cylinder petrol engine has a swept volume of 2000 cm3, and the clearance volume in
each cylinder is 60 cm3. Calculate the air standard cycle efficiency.
A. 59.1 %
B. 49.1 %
C. 39.1 %
D. 69.1 %
ANS: A

4. The compression ratio of an ideal Otto cycle is 6:1. Initial conditions are 101.3 kPa and 20 deg
C. Find the pressure and temperature at the end of adiabatic compression.
A. 1244.5 kPa, 599.96°K
B. 1244.5 kPa, 60°C
C. 1244.5 kPa gage, 60°C
D. 1244.5 kPa, 599.96°C
ANS: A

5. In an standard Otto cycle, the clearance volume is 18% of the displacement volume. Find the
thermal efficiency.
A. 0.52
B. 0.53
C. 0.55
D. 0.60
ANS: A

6. The compression ratio of an ideal Otto Cycle is 5:1. Initial conditions are 101.3 kPa and 22°C.
Find the pressure and temperature at the end of adiabatic compression.
A. 964.2 kPa, 288.6°K
B. 964.2 kPa, 288.6°C
C. 964.2 kPa, 561.6°C
D. 964.2 kPa, 561.6°F
ANS: A

7. An ideal Gasoline Engine (4-stroke) operates with an initial cycle temperature of 48°C and
exhaust temperature of 150°C. The change in temperature during combustion is 150°K. Find
the efficiency of the cycle.
A. 32%
B. 28%
C. 26%
D. 57%
ANS: A
8. An Otto engine has a clearance volume of 7%. It produces 300 kW power. What is the heat
rejected in kW?
A. 170
B. 160
C. 152
D. 145
ANS: A

9. In an air-standard Otto cycle, air enters at 1 bar and 20°C; the compression ratio is 8:1. If the
net work of the cycle is 100 kJ/kg, what is the heat supplied, in kJ/kg?
A. 78
B. 178
C. 278
D. 378
ANS: A

10. A diesel engine has an inlet temperature and pressure of 15°C and 100 kPaa, respectively. The
compression ratio is 12:1 and the maximum cycle temperature is 1100°C. Calculate the air
standard thermal efficiency based on the diesel cycle.
A. 58%
B. 45%
C. 53%
D. 64%
ANS: A

11. Operating on hot-air standard, the volumes of states 1, 2, and 3 of a diesel cycle 250 cm 3, 25
cm3 and 50 cm3, respectively. If the heat input is 100 kW, find the power output, in kJ/s.
A. 30
B. 45
C. 90
D. 230
ANS: A

12. Calculate the air standard efficiency of a diesel engine with a compression ratio of 15/1 and
maximum and minimum cycle temperature of 1650°C and 15°C respectively. The maximum
cycle pressure is 45 bar.
A. 58%
B. 45%
C. 53%
D. 59.1%
ANS: A

13. An air standard engine has a compression ratio of 20 and a cut-off ratio of 5. If the intake air
pressure and temperature are 100 kPa and 27°C, find the work in kJ per kg.
A. 2975
B. 2166
C. 2437
D. 2751
ANS: A

14. An air-standard diesel cycle, starts compression at 101.3 kPa and 30°C. The compression ratio
is 12 to 1. The maximum cycle temperature is 1600°C. Determine the thermal efficiency.
A. 51.19%
B. 53.12%
C. 54.97%
D. 55.12%
ANS: A

15. An air-standard diesel cycle, operates with a compression ratio of 16 to 1. The ratio of the fuel
by volume is 1.5. What is the cycle efficiency?
A. 34%
 B. 58%
C. 64%
D. 62%
ANS: A

16. An ideal diesel engine operates on 1 kg of cold air with a suction pressure of 100 kPa and an
initial temperature of 49°C. The compression pressure is 3170 kPa and the cut off is at 7% of
the stroke from head-end to bottom-end center of the piston. Determine the ideal cycle thermal
efficiency.
A. 42.19
B. 57.81
C. 43.09
D. 75.66
ANS: A

17. 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. 73.5
C. 51.2
D. 45.3
ANS: A

18. The thermal efficiency of a particular engine operating on an ideal cycle is 35%. Calculate the
heat in kJ supplied to the engine if the engine develops 1200 W-hr.
A. 12,343 kJ
B. 10,216 kJ
C. 14,218 kJ
D. 11,108 kJ
ANS: A

19. A 2000 kW diesel engine unit uses 1 bbl. Oil per 525 kw-hr produce. Oil is 25oAPI. Efficiency
of generator 93%, mechanical efficiency of engine 80%. What is the thermal efficiency based
on indicated power (%)?
A. 31.69
B. 29.47
C. 39.6
D. 35.6
ANS: A

20. A diesel engine power plant uses 157 gallons fuel oil at 40 deg. API during an hour’s run when
delivering 2000 kw. The fuel’s heating value is 44194 kJ/kg. Compute the plant thermal
efficiency.
A. 0.352
B. 0.362
C. 0.332
D. 0.302
ANS: A

21. A diesel electric plant supplies energy for Meralco. During a 24 hour period, the plant
consumed 200 gallons of fuel at 28°C and produced 3930 kw-hr. Industrial fuel used is 28
degree 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-hr?
A. P 1.05
B. P 1.10
C. P 1.069
D. P 1.00
ANS: A
22. Determine the size of cylinder of a six-cylinder, single acting, two stroke, 1000 kW diesel
engine running at 120 rpm when the pressure in each cylinder is 300 kPa. The mechanical
efficiency is 86% and the length of the stroke is 30% greater than the diameter of the cylinder.
(Answer in mm).
A. 680 x 886
B. 700 x 910
C. 480 x 624
D. 580 x 754
ANS: A

23. A 3000 kw diesel generating set which is using a 25°API fuel has the following data: fuel rate,
290 liters for 900 kw-hr, generator efficiency is 92% and mechanical efficiency is 82%.
Calculate the engine-generator fuel rate in kg/kw-hr.
A. 0.2916
B. 0.4587
C. 0.3567
D. 0.9857
ANS: A

24. A V-8 four-stroke petrol engine is required to give 186.5 kW at 4400 rev/min. The brake
thermal efficiency can be assumed to be 32% at the compression ratio of 1 . The air-fuel ratio
is 12/1 and the volumetric efficiency at this speed is 69%. If the stroke to bore ratio is 0.8,
determine the cylinder dimensions. The heating value of the fuel is 44,200 kJ/kg, and the free
air conditions are 1.013 bar and 15°C.
A. 100.5 mm x 80.4 mm
B. 700 x 910
C. 480 x 624
D. 580 x 754
ANS: A

25. A single acting, four-cylinder, 4-stroke cycle diesel engine with a bore X 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 mean effective pressure in kPa?
A. 415.20
B. 124.17
C. 319.95
D. 645.33
ANS: A

26. A six-cylinder, four-stroke, diesel engine with 76 mm bore and 89 mm stroke was run in the
laboratory at 2000 rpm, when it was found that the engine torque 153.5 N-m with all 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 45,120 kJ/kg and 252.2 kg of air at 15.6°C per hour. Determine the
indicated power.
A. 32.1 kW
B. 38.4 kW
C. 23.3 kW
D. 48.3 kW
ANS: A

27. A single-acting, four cylinder, 4-stroke cycle diesel engine with a bore to stroke of 4 in x 7 in,
operating at 1200 rpm, consumes 12.5 kg/hr of fuel. The load on the brake arm, which is 100
cm length is 150 kg. What is the brake mean effective in kPa?
A. 2905 kPa
B. 3207 kPa
C. 300 kPa
D. 307 kPa
ANS: A
28. In a double acting, 2-stroke compression ignition engine, 8 cylinders, the diameter of the
cylinder is 700 mm, stroke is 1350 mm and the piston rod diameter is 250 mm. When running
at 108 rpm, the indicated mean effective pressure above and below the piston are 5.80 bar and
4.90 bar, respectively. Calculate the brake power of the engine with a mechanical efficiency of
80% in kW.
A. 6050
B. 6030
C. 6010
D. 6070
ANS: A

29. A supercharged, six-cylinder, four-stroke cycle diesel engine of 10.48 cm bore and 12.7 cm
stroke has a compression ratio of 15. When it is tested on a dynamometer with a 53.34 cm arm
at 2500 rpm, the scale reads 81.65 kg, 2.86 kg of fuel of 45,822.20 kJ/kg heating value are
burned during a 6 min. test, and air metered to the cylinders at the rate of 0.182 kg/s. Find the
brake thermal efficiency.
A. 0.327
B. 0.367
C. 0.307
D. 0.357
ANS: A

30. A 3530 PS diesel engine with a specific fuel consumption of 0.243 kg/kw-hr uses fuel oil with
a relative density of 0.85 at 32°C. 40 metric tons of lubricating oil circulate thru the engine per
hour, the inlet temperature is 25°C and exit at 50°C. Taking the specific heat of the oil as 2.1
kJ/kg-K, calculate the heat carried away by it as percentage of the heat supplied to the engine.
A. 8.8%
B. 10.5%
C. 8.75%
D. 7.4%
ANS: A

31. An atmospheric cooling tower is to provide cooling for the jacket water of a four-stroke, 800
kW diesel generator. The cooling tower efficiency is 60% at a temperature of approach of
10°C. If ambient air has a relative humidity of 70%, dry-bulb temperature of 32°C and wet-
bulb temperature of 27.8°C, determine the cooling water supplied to the diesel engine in
liters/hr. Generator efficiency is 97%.
A. 50,500
B. 48,000
C. 42,000
D. 46,050
ANS: A

32. The average indicator card from a nine cylinder four stroke cycle 5.5 bore by 6 in. stroke
engine is 4 in. long and has an area of 6 sq. in. The maximum card height is 3.5 in. and
represents a maximum pressure rise of 666 psi. Find the indicated mean effective pressure.
A. 285.8 psi
B. 345.2 psi
C. 125.3 psi
D. 327.4 psi
ANS: A

33. A certain diesel engine with the following specifications, 8 cylinder, 400 mm x 600 mm, four
stroke cycle has a fuel consumption of 0.6 lb/hp-hr based on 19,100 Btu/lB. Engine speed is
280 rpm with an indicated mean effective pressure of 130 psi. If the jacket water carries away
an estimated 25% of the heat supplied, find its capacity (gpm) required if the allowable rise is
40°F.
A. 241.9
B. 236.5
C. 249.1
D. 268.7
 ANS: A

34. In a test laboratory, it was found out that the 80 Bhp developed by an engine on test, 45 hp are
absorbed by the cooling water that is pumped through the water jacket and the radiator. The
water enters the top of the radiator at 200oF. At that temperature, enthalpy of the water is
168.07 Btu/lbm. Water leaves the bottom of the radiator at 190 oF and with an enthalpy of
158.03 Btu/lbm. What is the water flow rate for a steady-state operation?
A. 25 gal/min
B. 20 gal/min
C. 23 gal/min
D. 24 gal/min
ANS: A

35. Find the power, which a 2.5 MW natural gas engine can develop at an altitude of 1981.2 meters
taking into consideration the pressure and temperature change.
A. 2.113 MW
B. 1.912 MW
C. 3.51 MW
D. 2.78
ANS: A

36. A 1 MW diesel power plant uses 2 bbl fuel at 26°API per 75,000 watts of electricity in 24 hrs
operation. Efficiency of generator is 92% and mechanical efficiency of 85%. What is the
thermal efficiency of the engine based on indicated power?
A. 64.80%
B. 56.90%
C. 59.37%
D. 35.80%
ANS: A

37. A 16-cylinder, V-type diesel engine, 4-stroke cycle, 514 rpm, 400 mm bore x 460 mm stroke is
directly coupled to a 5500 kw AC generator, 13,800 volts, 3 phase, 60 cycles and 93%
efficiency. Calculate the BHP of the diesel engine.
A. 7,927.6
B. 9,347.5
C. 8,267.5
D. 6,756.9
ANS: A

38. A single cylinder, double acting, reciprocating steam engine has a 6 in bore, and 8 in stroke,
and a piston rod diameter of 1 ¼ in. The average mean effective pressure found from the
indicator cards is 62 psi for each end of the cylinder. The engine operates at 300 rpm and with
a mechanical efficiency of 83%. If the engine is directly coupled to a generator having an
efficiency of 92%, find the generator output in kilowatts.
A. 21.1
B. 14.2
C. 16.1
D. 11.85
ANS: A

39. ?The area of an indicator diagram taken off a four-cylinder single acting, four stroke internal
combustion engine when running at 5.5 rps is 390 mm2. The length is 70 mm and the scale of
the indicator spring is 1 mm = 0.3 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.
A. 18
B. 20
C. 25
D. 30
ANS: A
40. ?A four-cycle, six-cylinder diesel engine of 108 mm bore and 152 mm running at 1200 rpm has
9% CO3 present in the exhaust gases. The fuel consumption is 5.76 kg per hour. Assuming that
13.7% CO2 indicates an air-fuel ratio of 15 kg air to 1 kg of fuel; calculate the volumetric
efficiency of the engine. The intake air temperature is 15.6°C and the barometric pressure is
757 mm Hg ab.
A. 80%
B. 76%
C. 83%
D. 95%
ANS: A

41. A waste heat recovery boiler produces 1 MPa dry saturated steam from 100°C feedwater. The
boiler receives hot gases (Cp = 1.0) at 4.2 kg per sec at a temperature of 950°C. After passing
through the waste heat boiler, the temperature of hot gases has been reduced to 250°C. How
much steam in kg is produced per hour? Note: At 1 MPa dry saturated, h = 2778.1 kj/kg.
A. 4487.8 kg
B. 4847.8 kg
C. 4748.8 kg
D. 4887.4 kg
ANS: A

42. A 3500-Bhp turbocharged diesel engine, 16-cylinder, 400 mm x 500 mm, 360 rpm has a fuel
consumption of 0.173 kg/Bhp-hr at full load using fuel with heating value of 10,900 kcal/kg.
For this engine, heat carried by exhaust gases is 30% and heat carried by jeacket water is 23%.
A waste heat recovery boiler recovers 35% of the exhaust heat loss. Calculate the quantity of
136 kPa steam that can be produced in kg/hr if jacket water from engine at 70°C is used as
boiler feeD. Note: at 136 kPa, hg = 2689.12 kJ/kg; at 70°C, hf = 292.98 kJ/kg.
A. 1120.7
B. 1210.7
C. 1720.1
D. 1270.1
ANS: A

43. An induced draft cooling tower is used by a 400 kW diesel engine to cool the jacket water from
60°C to 38°C. The average brake-thermal efficiency of the engine is 30% and the heat loss to
the jacket cooling water is 32%. The tower receives atmospheric air at 101.325 kPa, 32°C DB
and 28°C WB. (RH=62%). Air leaves the tower at 38°C DB at 90% RH. Make-up water enters
the cooling tower at 23°C. Calculate the required theoretical capacity of the cooling tower in
liters/min. (32°C, Psat = 4.76 kPa; 38°C, Psat = 6.632 kPa).
A. 270
B. 320
C. 378
D. 400
ANS: A

44. A four-stroke cycle diesel engine with 16:1 compression ratio drives a 500 kW generator at
1200 rpm. The generator efficiency is 90%. At this condition the engine A:F ratio is 20:1 and
the brake specific fuel consumption is 6.75 x 10-5 kg/s-kW. The inlet air conditions are 90 kPa
and 35°C. The original volumetric efficiency is 85%, stroke is 1.2 times the bore. Determine
for a six cylinder engine the bore and stroke per cylinder.
A. 27 mm x 87 mm
B. 320
C. 378
D. 400
ANS: A

45. An 8-cylinder, 254 mm x 305 mm, 4 cycle, 300 rpm, diesel engine operates with a brake
thermal efficiency of 30% at full load using fuel with a rating of 30 deg. API. Air-fuel ratio is
35 and volumetric efficiency is 70% based on atmospheric air at 100 kPa and 26.7°C.
Determine the rated power of the engine.
A. 98 kW
 B. 320
C. 378
D. 400
ANS: A

46. A 254 mm x 457 mm twin cylinder 4 stroke engine operates with a mean effective pressure of
655 kPag at 200 rpm. If the actual developed torque is 814 N-m, what is the friction power?
A. 33.51 kW
B. 25
C. 29
D. 30
ANS: A

47. Determine the standard diesel engine rating if it requires 367 gal/hr of cooling water and 12°F
cooling water temperature difference.
A. 13.5 Hp, StD. 15.0 hp
B. 2
C. 3
D. 4
ANS: A

48. An 8-cylinder, 450 mm x 600 mm, 4 stroke cycle diesel engine has an exhaust gas mass rate of
4.5 kg/kw-hr brake based on fuel having an air-fuel ratio of 20 to 1 and heating value of 10,540
kcal/kg. Engine speed is 260 rpm with brake mean effective pressure of 9.25 kg/cm 2. An
estimated 22% energy loss is carried away by the jacket cooling water. Calculate the brake
horsepower.
A. 2110 BHP
B. 2011 BHP
C. 2310 BHP
D. 2910 BHP
ANS: A

49. A 1 MW diesel power plant uses 2 bbl fuel at 26°API per 75,000 watts of electricity in 24 hrs
operation. Efficiency of generator is 92% and mechanical efficiency of 85%. What is the
thermal efficiency of the engine based on indicated power?
A. 64.80%
B. 56.90%
C. 59.37%
D. 35.80%
ANS: A

50. A 16 cylinder diesel engine is directly coupled to a 2400 volts, 3300 kw alternator. The engine
consumes 1.252 drums of 25° API diesel fuel with energy output of 990 kw-hrs. The
mechanical efficiency of the engine is 83% and the alternator efficiency is 92%. Assume a
drum of fuel contains 200 liters. Find the engine fuel rate in kg/bhp-hr.
A. 0.571
B. 0.715
C. 0.157
D. 0.751
ANS: A

51. A 16-cylinder, V-type diesel engine, 4-stroke cycle, 514 rpm, 400 mm bore x 460 mm stroke is
directly coupled to a 5500 kw AC generator, 13,800 volts, 3 phase, 60 cycles and 93%
efficiency. Calculate the BHP of the diesel engine.
A. 7,927.6
B. 9,347.5
C. 8,267.5
D. 6,756.9
ANS: A
52. A 2000 kW diesel engine unit uses 1 bbl. Oil per 525 kw-hr produceD. Oil is 25oAPI.
Efficiency of generator 93%, mechanical efficiency of engine 80%. What is the thermal
efficiency based on indicated power (%)?
A. 31.69
B. 29.47
C. 39.6
D. 35.6
ANS: A