PPE Looksfam 1 Flashcards
1
Q
Find the work possess for a helium gas at 20°C.
A
609 kj/kg
2
Q
Find the enthalpy of Helium if its internal energy is 200 kJ/kg.
A. 4.6 kW
B. 5.7 kW
C. 7.4 kW
D. 8.4 kW
A
333.42 KJ/kg
3
Q
A water-jacketed air compressor handles 0.343 m3/s of air entering at 96.5 kPa and 21°C and leaving at 480 kPa and 132°C; 10.9 kg/hr of cooling water enters the jacket at 15°C and leaves at 21°C. Determine the compressor brake power.
A. 23.163 kW
B. 62.65 kW
C. 34.44 kW
D. 19.33 kW
A
62.65 kW
4
Q
The suction pressure of a pump reads 3 in. of mercury vacuum and discharge pressure reads 140 psi is used to deliver 120 gpm of water with specific volume of 0.0163 ft3/lb. Determine the pump work
A. 4.6 kW
B. 5.7 kW
C. 7.4 kW
D. 8.4 kW
A
7.4 kW
5
Q
A submersible, multi-stage, centrifugal deep well pump 260 gpm capacity is installed in a well 27 ft below the static water level and running at 3000 rpm. Drawdown when pumping at rated capacity is 10 feet. The pump delivers the water into a 25,000 gallons capacity overhead storage tank. Total discharge head developed by pump, including friction in piping is 243 ft. Calculate the diameter of the impeller of this pump in inches if each impeller diameter developed a head of 38 ft.
A. 3.28
B. 5.33
C. 3.71
D. 6.34
A
3.71
6
Q
The charge in a Diesel engine consists of 18.34 grams of fuel, with lower heating value of 42,571 kJ/kg, and 409 grams of fuel and products of combustion. At the beginning of compression, T1 = 60°C. Let rk = 14. For constant cp = 1.11 kJ/kg-°C, what should be the cut-off ratio in the corresponding ideal cycle?
A. 2.05
B. 2.34
C. 5.34
D. 2.97
A
2.97
7
Q
An auditorium seating 1500 people is to be maintained at 80°F dry bulb and 60°F wet bulb temperature when outdoor air is at 91°F dry bulb and 75°F wet bulb. Solar heat load is 110,000 Btu/hr and supply air is at 60°F, determine the amount of supply air.
A. 93,229.17 lb/hr
B. 83,229.17 lb/hr
C. 73,229.17 lb/hr
D. 63,229.17 lb/hr
A
93,229.17 lb/hr
8
Q
A 35% solution leaves the absorber and 30% solution enters the absorber. The heat removed from the absorber by cooling water is 547.6 Btu and ammonia is superheated by 10°. Find the pound per pound of ammonia gas from the evaporating coils.
A. 11
B. 12
C. 13
D. 14
A
13
8
Q
Assume 8 ft3 of air at 100 psi and 100°F are compressed isothermally to a volume of 2 ft3. For each end state of the process, find the bulk modulus.
A. 400 and 100 psi
B. 400 and 110 psi
C. 400 and 120 psi
D. 400 and 130 psi
A
400 and 100 psi
9
Q
An empty, open can is 30 cm high with a 15 cm diameter. The can, with the open end down, is pushed under water with a density of 1000 kg/m3. Find the water level in the can when the top of the can is 50 cm below the surface.
A. 17.20 cm
B. 2.12 cm
C. 4.20 cm
D. 5.87 cm
A
2.12 cm
10
Q
Determine the size of pipe which will deliver 8 liters of medium oil (ν = 6.10x10-6 m2/s) assuming laminar flow conditions.
A. 622 mm
B. 754 mm
C. 950 mm
D. 835 mm
A
835 mm
11
Q
Carbon dioxide flows through a nozzle with a speed of 400 m/s. Compute the dynamic temperature.
A. 92.56 K
B. 94.56 K
C. 96.56 K
D. 98.56 K
A
94.56 K
12
Q
Air enters a diffuser with a velocity of 200 m/s. Determine the velocity of sound if air temperature is 30°C.
A. 349 m/s
B. 359 m/s
C. 369 m/s
D. 379 m/s
A
349 m/s
13
Q
Air flows through a nozzle with temperature of entrance of 420 K stagnation temperature of 468 K. Find the Mach number
A. 0.744
B. 0.754
C. 0.764
D. 0.774
A
0.754
14
Q
An insulated rigid tank initially contains 1.5 lb of helium at 80°F and 50 psia. A paddle wheel with power rating of 0.02 hp is operated within the tank for 30 min. Determine the final temperature.
A. 159.22°F
B. 169.22°F
C. 179.22°F
D. 189.22°F
A
179.22°F
15
Q
Consider a refrigerator whose 40 watts light bulb remains on continuously as a result of a malfunction of the switch. If the refrigerator has a COP of 1.3 and the cost of electricity is 8 cents per kW-hr, determine the increase in the energy consumption of the refrigerator and its cost per year if the switch is not fixed.
A. P 49.59
B. P 47.59
C. P 45.59
D. P 43.59
A
P 49.59
16
Q
Air in an ideal Diesel cycle is compressed from 3 L to 0.15 L and then it expands during the constant pressure heat addition process to 0.3 L. Under cold air standard conditions, the thermal effieciency of this cycle is?
A. 35%
B. 44%
C. 65%
D. 70%
A
65%
17
Q
In an ideal Otto cycle, air is compressed from 1.20 kg/m3 and 2.2 L to 0.26 L and the net work output of the cycle is 440 kJ/kg. The mean effective pressure for the cycle is?
A.612 kPa
B. 599 kPa
C. 528 kPa
D. 416 kPa
A
599 kPa
18
Q
An ideal Brayton cycle has a net work output of 150 kJ/kg and backwork ratio of 0.4. if both the turbine and the compressor had an isentropic efficiency of 80%, the net work output of the cycle would be?
A.60 kJ/kg
B. 75 kJ/kg
C. 98 kJ/kg
D. 120 kJ/kg
A
75 kJ/kg
19
Q
Air enters a turbojet engine at 200 m/s at a rate of 20 kg/s and exits at 800 m/s relative to the aircraft. The thrust developed by the engine is?
A. 6 kN
B. 12 kN
C. 16 kN
D. 20 kN
A
12 kN
20
Q
A heat engine receives heat from a source at 1200 K at a rate of 500 kJ/s and rejects the wasted heat to a sink at 300 K. If the power output of the engine is 200 kW, the second law efficiency of this heat engine is?
A. 35%
B. 40%
C. 53%
D. 75%
A
53%
21
Q
A water reservoir contains 100,000 kg of water at an average elevation of 60 m. The maximum amount of electric power that can be generated from this water is ?
A. 8 kWh
B. 16 kWh
C. 1630 kWh
D. 58,800 kWh
A
16 kWh
22
Q
A household refrigerator with EER 8.0 removes heat from the refrigerated space at a rate of 90 kJ/min. Determine the rate of heat transfer to the kitchen air.
A. 101.25 kJ/min
B. 63.05 kJ/min
C. 128.46 kJ/min
D. 80 kJ/min
A
128.46 kJ/min
23
Q
A refrigeration system is to cool bread loaves with an average mass of 450 g from 22°C to - 10°C at a rate of 500 loaves per hour by refrigerated air. Taking the average specific and latent heats of bread to be 2.93 kJ/kg-°C and 109.3 kJ/kg, respectively, determine the product load.
A. 541.7 kJ/min
B. 351.6 kJ/min
C. 761.5 kJ/min
D. 409.9 kJ/min
A
761.5 kJ/min
24
An ammonia simple saturation cycle operates with a suction pressure of 291.6 kPa and a condenser pressure of 1204 kPa develops 15 tons of refrigeration. Determine the theoretical horsepower of the compressor. The following enthalpies have been found: condenser entrance
= 1653 kJ/kg, exit = 346.6 kJ/kg; compressor entrance = 1450.2 kJ/kg, exit = 1653 kJ/kg.
A. 7.23 hp
B. 13 hp
C. 15 hp
D. 8.23 hp
13 hp
25
An ammonia ice plant operates between a condenser temperature of 35°C and evaporator of -15°C. It produces 10 metric tons of ice per day from water at 30°C to ice at -5°C. Assuming simple saturation cycle, determine the horsepower of the motor if the adiabatic efficiency of the compressor nc = 0.85 and mechanical efficiency nm = 0.95. The specific heat of ice is 2.094 kJ/kg-°C and the latent heat is 335 kJ/kg. From the table for ammonia the following enthalpies are: condenser entrance = 1703 kJ/kg, exit = 366.1 kJ/kg; compressor entrance = 1443.9 kJ/kg, exit = 1703 kJ/kg.
A. 17.68 hp
B. 18.61 hp
C. 15.5 hp
D. 21.9 hp
21.9 hp
26
Freon 22 air conditioning under standard operating conditions of 35°C condensing and 5°C evaporating temperatures. The volume flow rate entering the compressor is 23.72 L/s. Determine the refrigerating capacityif the refrigerating effect is 164 kJ/kg. From the table for R22 the specific volume at the compressor entrance is 40.46 L/kg.
A. 339.3 TR
B. 79.3 TR
C. 96.4 TR
D. 27.4 TR
27.4 TR
27
The refrigerant volume flow rate at the entrance of compressor were obtained from a test on a twin cylinder, single acting 15 cm x 20 cm, 320 rpm compressor ammonia refrigerating plant to be 33 L/s. Determine the volumetric efficiency of the compressor.
A. 77.65%
B. 87.6%
C. 97.6%
D. 65.65%
87.6%
28
The refrigerant volume flow rate at the entrance of compressor were obtained from a test on a twin cylinder, single acting 15 cm x 20 cm, 320 rpm compressor ammonia refrigerating plant to be 33 L/s. Determine the volumetric efficiency of the compressor.
A. 77.65%
B. 87.6%
C. 97.6%
D. 65.65%
87.6%
29
A twin cylinder ammonia compressor with volume displacement of 14,726 cm3 operates at 300 rpm. Condenser and evaporator pressure are 1200 kPa and 227 kPa respectively. Specific volume of refrigerant at the entrance of compressor is 528.26 L/kg. Compression process is polytropic with n = 1.20 and clearance factor of compressor is 2 percent. Determine the horsepower required.
A.60 hp
B. 70 hp
C. 80 hp
D. 90 hp
80 hp
30
Saturated vapor ammonia at -16°C (hT = 1442.60 kJ/kg) leaves the evaporator and enters the compressor at -6°C (h1 = 1465 kJ/kg). The refrigerant leaves the condenser as saturated liquid at 40°C (h4 = 390.6 kJ/kg) and enters the expansion valve at 35°C (h5 = 366.1 kJ/kg). Heat rejected from the condenser amount to 50 kW. The work to compressor is 208 kJ/kg, while the heat loss from compressor is 33 kJ/kg. If 95 kJ/kg of heat are lost in the piping between the compressor discharge and condenser inlet, determine the refrigerating capacity of the system.
A. 49.5 TR
B. 46.61 TR
C. 12.88 TR
D. 13.24 TR
13.24 TR
31
In an actual refrigeration cycle using R12 as working fluid, the refrigerant flow rate is 0.05 kg/s. Vapor enters the expansion valve at 1.15 MPa, 40°C (h = 238.5 kJ/kg) and leaves the evaporator at 175 kPa, -15°C (h = 345 kJ/kg). The electric iput to motor driving the compressor is measured and found 3.0 kW. Motor efficiency at this load 92% and mechanical efficiency 82%. Determine the actual coefficient of performance for this cycle.
A. 1.58
B. 2.36
C. 1.78
D. 1.34
2.36
32
In an ammonia refrigeration system, the temperature in the evaporator is -12°C and the ammonia at the evaporator entry 0.1511 dry while at exit is 0.95 dry. If the rate of ammonia circulation is 5.64 kg/min, determine the refrigerating capacity of the system. Enthalpy of saturated liquid and vapor at -12°C is 144.929 kJ/kg and 1447.74 kJ/kg respectively.
A. 17.82
B. 34.82
C. 27.82
D. 4.82
27.82
33
An ammonia water-cooled compressor receives the refrigerant at specific volume 62 L/kg. It has a piston displacement rate of 5 m3/min. If a squirrel cage motor running at 1200 rpm drives the compressor and average piston speed is 490 m/min, calculate size of cylinder bore.
A. 20.4 cm
B. 26.0 cm
C. 16.13 cm
D. 13.6 cm
16.13 cm
34
A condenser vacuum gauge reads 715 mm Hg when the barometer stands at 757 mm Hg. State the absolute pressure in the condenser in kN/m2 or kPa.
A.5.6 kPa
B. 5.9 kPa
C. 6.5 kPa
D. 5.2 kPa
5.6 kPa
35
A water tank 18 ft wide, 14 ft long, and 4 ft high, calculate the pressure at the bottom of the tank.
A.1.733 psi
B. 1.999 psi
C. 2.337 psi
D. 3.773 psi
1.733 psi
36
The equivalent weight of mass 10 kg at a location where the acceleration of gravity is 9.77 m/s2?
A. 97.7 N
B. 79.7 N
C. 77.9 N
D. 977 N
97.7 N
37
100 g of water are mixed with 150 g of alcohol (density = 790 kg/m3). What is the specific volume of the resulting mixtures, assuming that the fluids mixed completely?
A. 0.82 x 10-3 m3/kg
B. 0.88 x 10-3 m3/kg
C. 0.63 x 10-3 m3/kg
D. 1.16 x 10-3 m3/kg
1.16 x 10-3 m3/kg
38
The water velocity of a 5 m x 1 m channel is 6 m/s. What is the annual energy produced if the net head is 120 m and the over-all efficiency is 80%?
A. 494,247,258 kW-hrs
B. 247,497,582 kW-hrs
C. 247,494,528 kW-hrs
D. 472,497,582 kW-hrs
247,494,528 kW-hrs
39
A 50,000 kW steam plant delivers an annual output of 238,000,000 kW-hr with a peak load of 42,860 kW. What is the annual load factor and capacity factor?
A. 0.634, 0.534
B. 0.643, 0.534
C. 0.634, 0.543
D. 0.643, 0.534
0.634, 0.543
40
If the air required for combustion is 20 kg per kg of coal and the boiler uses 3000 kg of coal per hr, determine the mass of gas entering the chimney. Assume an ash loss of 15%.
A. 40,664 kg/hr
B. 70,200 kg/hr
C. 62,550 kg/hr
D. 50,500 kg/hr
62,550 kg/hr
41
A two-stage compressor receives 0.35 kg/s of air at 100 kPa and 269 K and delivers it at 5000 kPa. Find the heat transferred in the intercooler
A. 70.49 kW
B. 80.49 kW
C. 90.49 kW
D. 100.49 kW
70.49 kW
42
A centrifugal pump discharged 20 L/s against a head of 17 m when the speed is 1500 rpm. The diameter of the impeller was 30 cm and the brake horsepower was 6.0. A geometrically similar pump 40 cm in diameter is to run at 1750 rpm. Assuming equal efficiencies, what brake horsepower is required?
A. 51.55 HP
B. 50.15 HP
C. 40.14 HP
D. 45.15 HP
40.14 HP
43
A pump delivers 20 cfm of water having a density of 62 lb/ft3. The suction and discharge gage reads 5 in. Hg vacuum and 30 psi respectively. The discharge gage is 5 ft above the suction gage. If pump efficiency is 70%, what is the motor power?
A. 5.31 HP
B. 3.31 HP
C. 4.31 HP
D. 6.31 HP
4.31 HP
44
Calculate the air power of a fan that delivers 1200 m3/min of air through a 1 m x 1.5 m outlet. Static pressure is 120 mm WG and density of air is 1.18.
A. 20.45 kW
B. 25.64 kW
C. 30.45 kW
D. 35.64 kW
25.64 kW
45
Determine the temperature for which a thermometer with degrees Fahrenheit is numerically twice the reading of the temperature in degrees Celsius.
A. -24.6
B. 320
C. 160
D. -12.3
320
46
During takeoff in a spaceship, an astronaut is subjected to acceleration equal to 5 times the pull of the earth’s standard gravity. If the astronaut is 180 lbm and the takeoff is vertical, what force does he exert on the seat?
A. 4810.9 N
B. 4414.5 N
C. 8829 N
D. 9620 N
4810.9 N
47
A pressure cooker operates by cooking food at a higher pressure and temperature possible at atmospheric conditions. Steam is contained in the sealed pot, with vent hole in the middle of the cover, allowing steam to escape. The pressure is regulated by covering the vent hole with a small weight, which is displaced slightly by escaping steam. Atmospheric pressure is 100 kPa, the vent hole area is 7-mm2, and the pressure inside should be 250 kPa. What is the mass of the weight?
A. 0.107 kg
B. 1.05 kg
C. 1.75 kg
D. 0.1783 kg
0.107 kg
48
A barometer can be used to measure an airplane’s altitude by comparing the barometric pressure at a given flying altitude to that on the ground. Determine an airplane’s altitude if the pilot measures the barometric pressure at 700 mm-Hg, the ground reports it at 758 mm-Hg, and the average air density is 1.19 kg/m3, g = 9.81 m/s2.
A. 636 m
B. 633 m
C. 366 m
D. 663 m
663 m
49
A mixture of 0.4 lbm of helium and 0.2 lbm of oxygen is compressed polytropically from
14.7 psia and 60°F to 60 psia according to n = 1.4. Determine the final temperature, T 2.
A. 727.7°R
B. 777.2°R
C. 722.7°R
D. 277.7°R
777.2°R
50
A mixture of 0.4 lbm of helium and 0.2 lbm of oxygen is compressed polytropically from
14.7 psia and 60oF t0 60 psia according to n = 1.4. Determine the polytropic work.
A. 139 Btu
B. 239 Btu
C. 339 Btu
D. 539 Btu
139 Btu
51
A pump in a municipality’s water-supply system receives water from the filtration beds and pumps it up to the top of a water tower. The tower’s height is 35 m, and the inlet piping to the pump is 2 m below the pump’s intake. The water temperature is 20 C, measured at both the inlet and the discharge from the pump. The mass flow rate through the pump is 100 kg/s, the diameter of the inlet piping is 25 cm, and the diameter of the discharge piping is 15 cm. Determine the power required by the pump.
A. 77.3 kW
B. 33.77 kW
C. 34.42 kW
D. 42.34 kW
33.77 kW
52
An adiabatic tank containing air is used to power an air turbine during times of peak power demand. The tank has a volume of 500 m3 and contains air at 1000 kPa and 500 K. Determine the mass remaining when the pressure reaches 100 kPa.
A. 273.37 kg
B. 672.73 kg
C. 772.73 k
D. 227.73 kg
672.73 kg
53
During a steady state operation, a gearbox receives 60 kW throughout the input shaft and delivers power through the output shaft. For the gearbox as the system, the rate of energy transfer is by convection, h = 0.171 kW/m2-K is the heat transfer coefficient, A = 1.0 m2 is the outer surface area of the gearbox, Tb = 300 K (27°C) is the temperature at the outer surface, Tf = 293 K (20°C) is the temperature of the surroundings away from the immediate vicinity of the
gearbox. Determine the power delivered to the output shaft in kW if the heat transfer rate is -
1.2 kW.
A. 98.8 kW
B. 78.8 kW
C. 68.8 kW
D. 58.8 kW
58.8 kW
54
Determine the air-fuel ratio on a molar basis for the complete combustion of octane, with theoretical amount of air.
A. 95.5 kgair/kgfuel
B. 59.9 kgair/kgfuel
C. 59.5 kgair/kgfuel
D. 55.9 kgair/kgfuel
59.5 kgair/kgfuel
55
A single acting air compressor with a clearance of 6% takes in air at atmospheric pressure and temperature of 85°F and discharges it at a pressure of 85 psia. The air handled is 0.25 ft3/cycle measured at discharge pressure. If the compression is isentropic, find the piston displacement per cycle, if the compressor is running at 750 rpm.
A. 0.0750 ft3/cycle
B. 0.025 ft3/cycle
C. 1.030 ft3/cycle
D. 1.090 ft3/cycle
1.030 ft3/cycle
56
A single acting air compressor with a clearance of 6% takes in air at atmospheric pressure and temperature of 85°F and discharges it at a pressure of 85 psia. The air handled is 0.25 ft3/cycle measured at discharge pressure. If the compression is isentropic, find the air hp of the compressor if rpm is 750.
A. 16 hp
B. 96 hp
C. 69 hp
D. 61 hp
96 hp
57
A two-stage, double acting compressor is to deliver 90 lb/min of air from 14.3 psia to 90°F to a final pressure of 185 psia. The normal barometer is 29.8 in-Hg and the temperature is 80°F. The pressure drop in the intercooler is 3 psi and the speed is 210 rpm and pV1.34 = C during compression and expansion. The clearance is 5% for both cylinders. Find the volume of free air if the temperature of the cooling water increased by 18°F.
A. 1282 CFM
B. 1230 CFM
C. 1320 CFM
D. 1822 CFM
1230 CFM
58
Consider 4800 lb of steam per hour flowing through a pipe at 100 psia pressure. Assume a velocity of 5280 ft/min. What size of pipe is required? Specific volume of steam at 100 psia υ =
4.432 ft3/lb.
A. 3 in
B. 5 in
C. 4 in
D. 6 in
4 in
59
A boiler plant generates 225,000 lb of steam and burns 13.9 tons of coal per hour. The coal has a heating value of 11,400 Btu/lb. A test of the particulates leaving the boiler shows that 3804 lb of particulate is being discharged per hour. What is the particulate discharged per million Btu heat input to the furnace?
A. 12 lb/106 Btu
B. 14 lb/106 Btu
C. 15 lb/106 Btu
D. 16 lb/106 Btu
12 lb/106 Btu
60
A turbine receives 150 lbm/s of air at 63 psia and 2450°R and expands it polytropically to
14.7 psia. The exponent n is equal to 1.45 for the process. Determine the power
A. 52,343.16 BTU/s
B. 52,343.16 kW
C. 53.343.16 HP
D. 53,343.16 ft-lb/s
52,343.16 BTU/s
61
Find the thrust and efficiency of two 2-m diameter propellers through which flows a total of 600 m3/s of air to 11.3 N/m3. The propellers are attached to an airplane moving at 250 kph through still air. Neglect eddy losses.
A. 36,077 N, 73%
B. 77,630 N, 37%
C. 66,033 N, 33%
D. 77,330 N, 77%
36,077 N, 73%
62
A liquid with a specific gravity of 1.26 is being pumped in a pipeline from A to B. At A, the pipe diameter is 60 cm and the pressure is 300 kN/m2. At B, the pipe diameter is 30 cm and the pressure is 330 kN/m2. Point B is 1.0 m lower than A. Find the flow rate if the pump puts 16 kW into the flow. Neglect head loss.
A. 4.2 m3/s
B. 0.42 m3/s
C. 2.4 m3/s
D. 0.24 m3/s
0.42 m3/s
63
A reciprocating compressor handles 1,400 cfm of air measured at intake where P1 = 18 psia and T1 = 90°F. The discharge pressure is 92 psia. Calculate the work if the process of the compression is isothermal.
A. -180.5 hp
B. -179.5 hp
C. -227.6 hp
D. -228.6 hp
-179.5 hp
64
The fuel oil has the ff. analysis:
C = 89% N2 = 2% H2 = 8% S = 1%
With 3% excess air, what is the actual amount of air needed to burn the fuel oil?
A. 13.17 kgair/kgfuel
B. 13.47 kgair/kgfuel
C. 14.47 kgair/kgfuel
D. 14.17 kgair/kgfuel
14.17 kgair/kgfuel
65
A room contains air at 20°C and 96 kPa at a relative humidity of 75%. Determine the enthalpy of moist air.
where:
Given:
(Psat @ 20°C = 2.339 kPa) (hg @ 20°C = 2538.1 kJ/kgda)
Unsaturated air (0% < Ø <100%) td = 20°C
Pt = 96 kPa
Ø = 75%
A. 45.919 kJ/kgda
B. 45.515 kJ/kgda
C. 49.515 kJ/kgda
D. 41.815 kJ/kgda
49.515 kJ/kgda
66
A piston moves inside a cylinder at a velocity of 6.0 m/s. The 160 mm diameter piston is centrally located within the 160.2 mm inside diameter cylinder. The film of oil is separating the piston from the cylinder has an absolute viscosity of 0.4 N-s/m2. Assuming a linear velocity profile, find the shear stress in the oil. (T = μ (v/H))
Given:
μ = 0.40 N-s/m2 v = 5 m/s
H = thickness of oil film = 160.2 – 160/2 = 0.1 mm
A. 50,000 N/m2
B. 40,000 N/m2
C. 24,000 N/m2
D. 34,000 N/m2
24,000 N/m2
67
A centrifugal pump with a 3 ft impeller diameter operates at 800 rpm. If the speed is to be increased to 1200 rpm, determine the impeller diameter that should be used so that the same shaft input power would be required.
A. 5.32 ft
B. 2.35 ft
C. 5.23 ft
D. 2.93 ft
2.35 ft
68
Find the density of oil with a specific gravity of 1.6 in-g/cm3.
A. 15.68 g/cm3
B. 99.84 g/cm3
C. 0.8 g/cm3
D. 1.6 g/cm3
1.6 g/cm3
69
Steam enters a turbine stage with an enthalpy of 3700 kJ/kg and a velocity of 80 m/s and leaves with an enthalpy of 2864 kJ/kg with a velocity of 12.8 m/s. If the rate of a steam flow through the turbine is 0.44 kg/s, what is the work done in kW?
A. 365 kW
B. 365.64 kW
C. 366.0 kW
D. 366.50 kW
365.64 kW
70
Consider 1 kg of air at 32°C that expanded by a reversible polytropic process with n = 1.25 until the pressure is halved. Determine the heat transfer. Specific heat at constant volume for air is 0.1786 kJ/kg-K.
A. 17.02 kJ heat rejected
B. 7.05 kJ heat rejected
C. 17.02 kJ heat added
D. 7.05 kJ heat added
17.02 kJ heat added
71
A Carnot cycle uses nitrogen (k = 1.399) as the working substance. The heat supplied is 54 kJ and the adiabatic expansion ratio is 10. Determine the heat rejected.
A. 10 kJ
B. 32.4 kJ
C. 21.6 kJ
D. 54 kJ
21.6 kJ
72
An air compressor takes in 9 kg/min of air at 98 kPa; υ1 = 0.125 m3/kg and discharges it at 680 kPa; υ2 = 0.03 m3/kg. The increase of internal energy is 93 kJ/kg and the work done on air is
163 kJ/kg; the change in potential and kinetic energy are neglected. How much heat is transferred per kg of air?
A. 264.15 kJ/kg
B. 61.85 kJ/kg
C. 288.65 kJ/kg
D. 78.15 kJ/kg
61.85 kJ/kg
73
During a reversible process, there are abstracted 317 kJ/s from 1.134 kg/s of a certain gas while the temperature remains constant at 26.7°C. For this gas cp = 2.232 and cv = 1.713 kJ/kg-K. The initial pressure is 586 kPa. Determine the final volume flow rate.
A. 0.301 m3/s
B. 0.03 m3/s
C. 0.5 m3/s
D. 0.05 m3/s
0.05 m3/s
74
An air compressor has an inlet enthalpy of 35 Btu/lb and an exit enthalpy of 70 Btu/lb. The mass flow rate of air is 3 lb/s. If the heat loss is 466.62 Btu/min, find the work input to the compressor.
A. 139.59 hp
B. 149.59 hp
C. 159.59 hp
D. 169.59 hp
159.59 hp
75
A condenser vacuum gauge reads 600 mm Hg when the barometer reads 760 mm Hg. What is the absolute condenser pressure in bar?
A. 0.0213
B. 0.061
C. 0.213
D. 0.610
0.213
76
Determine the degrees of superheat of steam at 101.325 kPa and 170°C.
A. 50°C
B. 70°C
C. 60°C
D. 80°C
70°C
77
The quality of steam is 20%. This means that:
A. mass of liquid is 20%, mass of vapor is 80%
B. mass of liquid is 20%, mass of vapor is 0%
C. mass of liquid is 80%, mass of vapor is 20%
D. none of the above
mass of liquid is 80%, mass of vapor is 20%
78
Determine the quality of steam in a vessel containing 2 kg of saturated vapor and 8 kg of saturated liquid.
A. 100%
B. 20%
C. 80%
D. 60%
20%
79
One kilogram of air is compressed adiabatically and in a steady-flow manner. The compression efficiency is 80% and the work done on the air is 265 kJ/kg. Compute the heat.
A. 212 kJ/kg
B. 100 kJ/kg
C. 0 kJ/kg
D. 331.25 kJ/kg
0 kJ/kg
80
Three-hundred kilojoules of heat flow by conduction from the outside to the inside of a cold storage in one hour. If the temperature and all other conditions are the same, what is the heat flowing through the cold storage room in two hours?
A. 600 kJ
B. 900 kJ
C. 300 kJ
D. 1,200 kJ
600 kJ
81
Air enters a nozzle steadily at 2.21 kg/m3 and 30 m/s. What is the mass flow rate through the nozzle if the inlet area of the nozzle is 80 cm2?
A. 0.35 kg/s
B. 3.5 kg/s
C. 5.3 kg/s
D. 0.53 kg/s
0.53 kg/s
82
A small pump serving as model, when tested in laboratory using water at 3600 rpm, delivered 30 cfs at a head of 125 ft. If the efficiency of this model pump is 84%, predict the horsepower input to the prototype pump if it is to develop the same head as model pump and the model pump has a scale ratio of 1:10. Assume the efficiency of the prototype pump is 90%.
A. 50.6 hp
B. 4730 hp
C. 3740 hp
D. 60.5 hp
4730 hp
83
Pump at is best efficiency point (BEP) has a capacity of 10,500 gpm while developing a head of 60 ft at a rotative speed of 1450 rpm. What is the specific speed of the pump?
A. 2760
B. 1450
C. 2476
D. 6892
6892
84
A pump will be installed below the reservoir water surface with a required net positive suction head (NPSHR) of 50 ft. The barometric pressure is 14.3 psia, and the vapor pressure is
0.5 psia. Assume friction losses in the intake piping are 5 ft. Find the maximum allowable
elevation of the pump relative to the water surface intake to avoid cavitation.
A. 45 ft
B. 55 ft
C. 18.2 ft
D. 23.2 ft
23.2 ft
85
A 15 in. diameter fan operates at 1600 rpm and develops a head of 6 in. of water and delivers 120 cfm. What volumetric capacity for geometrically similar fan will develop 6 in of water at 1300 rpm?
A. 147.7 cfm
B. 181.8 cfm
C. 97.5 cfm
D. 79.2cfm
181.8 cfm
86
How many identical turbines, operating at 139.0 rpm and 91% efficiency (specific speed = 5.4), are needed to exploit a head of 1200 ft and a flow of 1660 ft3/s?
A. 2 turbines
B. 3 turbines
C. 4 turbines
D. 5 turbines
3 turbines
87
How many poles should a 60-Hz generator have, if it is connected to a turbine operating under a design head of 3000 ft with a flow of 82 cfs? Assume turbine specific speed and efficiency 3 and 84 percent respectively.
A.10-pole
B. 12-pole
C. 14-pole
D. 16-pole
16-pole
88
A 26-hp pump delivers 475 gpm of gasoline (γ = 42.5 lb/ ft3) at 20 C with 78% efficiency. What pressure rise result across the pump?
A. 30.2 psi
B. 32.7 psi
C. 120.3 psi
D. 73.2 psi
73.2 psi
89
A model pump delivering water at 180°F (γ = 60.6 lb/ ft3; pvapor = 7.54 psia) at 900 gpm and 2500 rpm begins to cavitate when the inlet pressure and velocity are 13 psia and 22 fps. Find the required NPSH of a prototype which is 4 times larger and runs at 1100 rpm.
A. 63.5 ft
B. 20.49 ft
C. 6.61 ft
D. 36 ft
63.5 ft
90
The diameter of the discharge pipe is 8 in. and that of the intake pipe is 10 in. The pressure gage at discharge reads 32 psi, and vacuum gage at the intake reads 12 in. Hg. If the discharge flow rate = 4.0 ft3/s of water and the brake horsepower is 49.0, find the efficiency. The intake and the discharge are at the same elevation.
A. 82.2%
B. 80.9%
C. 55.8%
D.58.46%
82.2%
91
A piston positive-displacement pump (PDP) has a 6-in diameter and a 2.5-in stroke. Its crankshaft rotates at 300 rpm. Calculate its output at 94 percent volumetric efficiency.
A. 12.27 cfm
B. 13.5 cfm
C. 10 cfm
D.11.53 cfm
11.53 cfm
92
A centrifugal pump (efficiency 88%) lifts water through a total height of 40 m from a reservoir to discharge. Pumping is through 300 m of 75 mm diameter pipe at the rate of 20 liter/s. If pipe friction, f = 0.025, what horsepower is required?
A. 28.4 kW
B. 32.2 kW
C. 25kW
D. 9kW
32.2 kW
93
In order to predict the behaviour of a small oil pump, tests are to be made on a model using air. The pump is to be driven by a 1/20-hp motor at 1800 rpm and a ¼-hp motor is available to drive the air at 600 rpm. Using specific gravity of oil at 0.912 and density of air constant at 0.076 lb/ ft3, what size model should be built?
A. The model should be 2 times as large as the oil pump.
B. The model should be 5 times as large as the oil pump.
C. The model should be 8 times as large as the oil pump.
D. The model should be 10 times as large as the oil pump.
The model should be 10 times as large as the oil pump.
94
An impulse wheel at best produces 125 hp under a head of 210 ft. By what percent should the speed be increased for a 290-ft head?
A. 82.25%
B. 17.5%
C. 72.41%
D. 27.59%
17.5%
95
What is the power ratio of a pump and its 1/5 scale model if the ratio of heads is 4 to 1?
A. 20
B. 200
C. 12.5
D. 125
200
96
The speed of a centrifugal pump is doubled. By what factor does the pump head change?
A. 0.125
B. 0.25
C. 4
D. 8
4
97
Compute the specific volume of an air-vapor mixture in cubic meter per kg of dry air when the following conditions prevail: t = 40°C, w = 0.015 kg/kg, and Pt = 90 kPa.
A. 0.99 m3/kg
B. 0.89 m3/kg
C. 0.79 m3/kg
D. 0.69 m3/kg
0.99 m3/kg
98
A rectangular duct has a dimension of 0.25 m by 2 m. Determine the equivalent diameter of the duct.
A. 0.50 m
B. 0.60 m
C. 0.70 m
D. 0.40 m
0.40 m
99
To what height will a barometer column rise if the atmospheric conditions are 13.9 psia and 68°F and barometer fluid is mercury?
A. 3.56 ft
B. 5.36 ft
C. 2.36 ft
D. 3.26 ft
2.36 ft
100
If atmospheric air 14.7 psia and 60°F at sea level, what is the pressure at 14212 ft altitude if air is incompressible? Note: @ 60°F, the density of air is 0.0763 lbm/ft3; P1 = 14.7 psia.
A. 5.4674 psia
B. 7.5304 psia
C. 7.1696 psia
D. 7.1966 psia
7.1696 psia
101
Water (ρ = 62.4 lbm/ft3) is flowing through a pipe. A pitot-static gage registers 3.0 inches of mercury. What is the velocity of the water in the pipe? Note: ρHg = 848.6 lbm/ft3.
A. 14.7 ft/s
B. 41.7 ft/s
C. 71.4 ft/s
D. 74.1 ft/s
14.7 ft/s
102
The mass of an outside air at 50°C in an air conditioning unit is 60 kg. Find the temperature after mixing if the outside air mixed with 40 kg with recirculated air at 35°C.
A. 44°C
B. 39°C
C. 52°C
D. 47°C
44°C
103
Five hundred kilograms of poultry enter a chiller at 8°C and are frozen and chilled to a final temperature of 18°C for storage in 15 hours. The specific heat above and below freezing are
3.18 kJ/kg-°C and 1.55 kJ/kg-°C respectively. The latent heat is 246 kJ/kg and the freezing
temperature is -5°C. Compute the product load.
A. 2.75 kW
B. 2.85 kW
C. 2.95 kW
D. 3.15 kW
2.85 kW
104
Fish weighing 11,000 kg with a temperature of 20°C is brought to a cold storage and which shall be cooled to -10°C in 11 hours. Find the required plant refrigerating capacity in tons of refrigeration if the specific heat of fish is 0.7 kCal/kg-°C above freezing point and 0.30 kCal/kg-
°C below freezing point. The freezing point is -3°C. The latent heat of freezing is 55.5 kCal/kg.
A. 25.26 TOR
B. 15.26 TOR
C. 14.38 TOR
D. 24.38 TOR
24.38 TOR
105
The power requirement of a Carnot refrigerator in maintaining a low temperature region at 300 K is 1.5 kW per ton. Find the heat rejected
A. 4.02 kW
B. 7.02 kW
C. 5.02 kW
D. 6.02 kW
5.02 kW
106
A vapor compression refrigeration system is designed to have a capacity of 150 tons of refrigeration. It produces chilled water from 22°C to 2°C. Its actual coefficient of performance is
5.86 and 35% of the power supplied to the compressor is lost in the form of friction and cylinder cooling losses. Determine the condenser cooling water required for a temperature rise of 10°C.
A. 14.75 kg/s
B. 15.65 kg/s
C. 18.65 kg/s
D. 13.75 kg/s
14.75 kg/s
107
Determine the heat extracted from 2000 kg of water from 25°C to ice at -10°C.
A. 621,150 kJ
B. 721,150 kJ
C. 821,150 kJ
D. 921,150 kJ
921,150 kJ
