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1
Find the work posses for a helium gas at 20C.
A. 609 KJ/kg
2
Two kilogram of gas is confined in a 1m³ tank 200kpa and 88degC. What type of gas is in the tank?
B. Ethane
3
Find the enthalpy of the helium if its internal energy is 200KJ/Kg.
C. 333.42 KJ/kg
4
Compute the mass of a 2m^3 propane at 280 kpa and 40degC.
D. 9.47
5
Compute the air flow in ft³/min of mechanical ventilation required to exhaust an accumulation of refrigerant due to leaks of the system capable of revolving air from the machinery room for a mass of 4lbs refrigerant.
A. 200
6
Compute the free aperture cross section in m² for the ventilation of a machinery room in the mass of refrigerant is 9 kg.
B. 0.414
7
A 29.53” X 39.37” pressure vessel contains ammonia with f=0.041. compute the minimum required discharge capacity of relief device in kg/hr.
C. 110.71 kg/hr
8
Compute the maximum length of discharge puipe installed on the outlet of a pressure- relief device in feet for the internal pipe diameter of 0.5 inch and rated discharge capacity is 8lb/min of air. The rated pressure of relief valve is 16 psig.
A. 0.286 ft.
9
A thermal power plant has a heat rate of 11,363 Btu/kw-hr. find the thermal efficiency of the plant.
B. 30%
10
What is the hydraulic gradient of a 1 mile, 17 inches inside diameter pipe when 3300 gal/ml of water flow with f= .03?
A. 0.00714
11
Find the loss of head in the pipe entrance if speed of flow is 10 m/s.
D. 2.55 m
12
Wet material containing 220% moisture (dry basis) is to be dried at the rate of 1.5 kg/s in a continuous dryer to give a product containing 10% (dry basis). Find the moisture removed, kg/hr.
A. 3543.75 kg/hr
13
Copra enters a dryer containing 70% moisture and leaves at 7% moisture. Find the moisture removed on each pound of solid in final product.
D. 2.258 lb
14
A 1m x 1.5m cylindrical tank is full of oil with sg=0.92. find the force acting at the bottom of the tank in dynes.
D. 106.33 x 10^6
15
Air at 10 deg. C and 80 Kpa enters a diffuser of a jet engine steadily with a velocity of 200 m/s. The inlet area of diffuser is 0.40 m^2. Determine the mass flow rate of air.
D. 78.79 kg/s
16
Consider a refrigeration whose 40 watts light bulb remains on continuously as a result of 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
17
A 75hp motor that has an efficiency of 91% is worn out and is replaced by high-efficiency motor that has an efficiency of 95.4%. Determine the reduction in heat gain in room due to higher efficiency under full load conditions.
B. 2.44 KW
18
A household refrigerator that has a power input of 450 watts and COP of 2.5 is to cool five large watermelons, 10 kg each, if the watermelons are initially at 20 deg. C, determine how long will take for the refrigerator to cool them. the watermelons can be treated as water whose specific heat is 4.2 KJ/kg- K.
C. 2240 seconds
19
When a maN returns to his wall-sealed house on a summer day, he finds that the house is at 32 deg. C. he turned on the air conditioner which cools the entire house to 20 deg. C in 15 minutes. If COP is 2.5, determine the power drawn by the air-conditioner. Assume the entire mass within the house is 800 kg of air for which Cv = 0.72 KJ/kg-K, Cp = 1.0 KJ/kg-K.
C. 3.072 KW
20
A heat source at 800 K losses 2000 KJ of heat to a sink at 500 K. Determine the entropy generated during this process.
A. 1.5 KJ./kg
21
A helium gas is compressed on in an adiabatic compressor from an initial state of 14 psia and 50 deg. F to a final temperature of 320 deg F in a reversible manner. Determine the exit pressure of helium.
B. 40.5 psia
22
Air pass thru a nozzle with efficiency of 90%. The velocity of air at the exit is 600 m/s. find the actual velocity at the exit.
D. 568 m/s
23
A 50 kg of iron casting at 500 K is thrown into a large lake that is at temperature of 285 K. the iron block eventually reaches thermal equilibrium with the lake water. Assuming average specific heat of 0.45 KJ/kg-K for the iron, determine the entropy generated during this process.
C. 4.32 KJ/K
24
A windmill with a 12 m diameter rotor is to be installed at location where the wind is blowing at an average velocity of 10 m/s. Using standard condition of air (1 atm, 25 deg. C), determine the maximum power that can be generated by the windmill.
B. 70 KW
25
Consider a large furnace that can supply heat at temperature of 2000 deg.R at a steady rate of 3000 Btu/s. Determine the exergy of this energy. Assume an environment temperature of 77 deg. F.
B. 2315.19 KW
26
A heat engine receives heat from a source at 1200 deg. K at rate of 500 KJ/s and rejects the waste heat to a medium at 300 deg. K. the power output of the heat engine is 180 KW. Determine the irreversibility rate for this process.
B. 195 KW
27
A dealer advertise that he has just received a shipment of electric resistance heaters for residential buildings that have an efficiency of 100 percent. Assuming an indoor temperature of 21 deg. C and outdoor temperature of 10 deg. C, Determine the second law efficiency of these heaters.
C. 3.74 %
28
A thermal power plant has a heat rate of 11,363 Btu/hr. find the thermal efficiency of the plant.
D. 30 %
29
A rigid tank contains 2 kmol of N2 and 6 kmol of CO2 gases at 300 deg. K and 115 Mpa. Find the tank volume using ideal gas equation.
D. 1.33 m^3
30
A spherical balloon with a diameter of 6 m is filled with helium at 20 deg. C and 200 Kpa. Determine the mole number.
A. 9.28 Kmol
31
The air in an automobile tire with a volume of 0.53 ft^3 is at 90 deg. F and 20 psig. Determine the amount of air that must be added to raise the pressure to the recommended value of 30 psig. Assume the atmospheric pressure to be 14.6 psia and the temperature and the volume to remain constant.
A. 0.026 lb
32
A rigid tank contains 20 lbm of air at 20 psia and 70 deg. F. more air is added to the tank until the pressure and temperature rise to 35 psia and 90 deg.F, respectively. Determine the amount of air added to the tank.
B. 13.73 lb
33
A rigid tank contains 5 kg of an ideal gas at 4 atm and 40 deg. C. Now a valve is opened, and half of mass of the gas is allowed to escape. If the final pressure in the tank is 1.5 atm. The final temperature in the tanks is:
A. -39 deg. C
34
The pressure of an automobile tire is measured to be 200 Kpa (gage) before the trip and 220 kpa (gage) after the trip at a location where the atmospheric pressure is 90 kpa. If the temperature of the air in the tire before the trip is 25 deg. C, the air temperature after the trip is:
A. 45.6 deg. C
35
Water boils at 1 atm pressure in a stainless steel pan on an electric range. It is observed that 2 kg of liquid water evaporates in 30 min. the rate of heat transfer to the water is>
C. 2.51 KW
36
Consider a person standing on a breezy room at 20 deg. C. Determine the total rate of heat transfer from this person if the exposed surface area and the average outer surface temperature of the person are 1.6 m^2 and 29 deg. C respectively, and the convection heat transfer coefficient is 6 W/m^2 with the emissivity factor of 0.95.
D. 168.1 watts
37
Water is boiling in a pan on a stove at sea level. During 10 minutes of boiling, it is observed that 200 grams of water has evaporated. Then the rate of heat transfer to the water is:
B. 45.1 KJ/min
38
In a brayton cycles that operates between temperature limits of 300K and 1773K with K=1.4, determine the temperature at the end of the compression (isentropic) for maximum work of the cycle.
C. 730 K
39
At 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 10deg. Find the pound per pound of ammonia gas from the evaporating coils.
C. 13
40
A carnot refrigeration system operates at Tmax./Tmin.= 1.5, Find the KW per to of refrigeration.
C. 1.76
41
Assume 8ft^3 of air at 100psi, 100degF are compressed isothermally to a volume of 2ft^3. For each of end state the process, find the bulk modulus.
A. 400 and 100 psi
42
Predict the pressure of nitrogen gas at T=200K and v=0.00385 m^3/kg and b=0.00141 m^3/kg; a=0.178 m^2 kpa/kg^2. Use van der waals equation,
D. 12,331 kpa
43
Francis turbine is to be operated at a speed of 600rpm and with discharge of 4m^3/s. if r1=0.6m, beta1=110deg, and the blade height B is 10cm, what should be the guide angle a1 for non separating flow condition at the runner entrance ?
D. 17.4 deg
44
The total head of fan is 187m and has a static pressure of 210mm of water gage, what is the velocity of air flowing if density of air is 1.15 kg/m^3 ?
D. 9.28 m/sec
45
A fan delivers 5.7 m^3/sec. at a static pressure of 5.08 cm of water when operating at a speed of 400rpm. The power input required is 2.963 KW. If 7.05 m^3/sec. are desired in the same fan and installation, find the pressure in cm of water.
A. 7.77
46
A rigid container is closed at one end and measures 8 in diameter by 12 in long. The container is held vertices and slowly moved downward until the pressure in the container is 17psia. What will be the depth of the top of the container from the free water surface?
C. 63.69 in
47
A turbo-charged, 16 cylinder, Vee-type diesel engine has an air consumption of 3,000 kg/hr per cylinder at rated load and speed, this air is drawn in through a filter by a centrifugal compressor directly connected to the exhaust gas turbine. The temperature of the air from the compressor is 135 DegC and a counter flow air cooler reduces the air temperature to 45 degC before it goes to the engine suction header. Cooling water enters air cooler 30 degC and leaves at 40 degC. Calculate the log mean temperature difference.
C. 43.34 degC
48
Water is flowing in a pipe with radius of 30 cm at a velocity of 5 m/sec at the temperature in the pipe. The density and viscosity of the water are as follows density = 997.9 kg/sec; viscosity = 1.131 Pa. what is the Reynolds number of this situation?
A. 2847
49
Compute the amount of condensate form during 10 minutes warm-up of 180 meter pipe conveyors the saturated steam with enthalpy vaporization hfg = 1,947.6 kj/kg. the minimum external temperature of pipe is 2 DegC. The final temperature of pipe is 195 degC. The specific heat of pipe material is 0.6 kj/kg-C. the specific weight if 28 g/m.
C. 299.64 kg
50
The discharge pressure of an air compressor is 5 times the suction pressure. If volume flow at suction is 0.1 m^3/sec. what is the suction pressure if compressor work is 19.57 kw? (use n = 1.35)
B. 98 Kpa
51
The initial condition of air in an air compressor is 93 Kpa and 27 deg. C and discharges air at 450 Kpa. The bore and stroke are 355 mm and 381 mm, respectively with percent clearance of 8% running at 300 rpm. Find the volume of air at suction.
D. 571.62m^3/hr
52
An air compressor has a suction volume of 0.35 m^3/sec at 97 Kpa and discharges to 650 Kpa. How much power is saved by the compressor if there are two stages?
D. 11.58 KW
53
A two stage air compressor has an intercooler pressure of 4 kg/cm^2. What is the discharge pressure if suction pressure is 1 kg/cm^2?
D. 16 kg/cm^2
54
A two-stage air compressor air at 100 Kpa and 22 deg. C discharges to 750 Kpa. If the intercooler intake is 105 deg.C, Determine the value of n.
D. 1.288
55
A single acting air compressor has a volumetric efficiency of 89%, operates at 500 rpm. It takes in air at 100 Kpa and 30 deg. C and discharges it at 600 Kpa. The air handled is 8 m^3/min measured at discharge condition. If compression is isentropic, find mean effective pressure in Kpa.
A. 233.34
56
Water-jacketed air compressor handles .0343 m^3/s of air entering at 96.5Kpa and 21 deg. C and leaving at 480 Kpa and 132 deg. C; 10.9 kg/h of cooling water enters the jacket at 15 deg. C and leaves at 21 deg. C, Determine the compressor brake power?
B. 62.650 kw
57
A double suction centrifugal pumps delivers 20 ft³/sec of water at head of 12 m and running at 650 rpm. What is the specific speed of the pump?
C. 2770.73 rpm
58
Determine the number of stages needed for a centrifugal pump if it used to deliver 400 gal/min of water and pump power of 15 Hp. Each impeller develops a head of 30 ft.
C. 5
59
The suction pressure of a pump reads 3 in. of mercury vacuum and discharge pressure reads 140 psi is use to deliver 120 gpm of water with specific volume of 0.0163 ft³/lb. Determine the pump work. (NO ANSWER YET)
B. 5.7 KW
60
A submersible pump delivers 350 gpm of water to a height of 5 ft from the ground. The pump were installed 150 m below the ground level and a drawdown of 8 ft during the operation, if the water level is 25 ft above the pump, determine the pump power.
D. 9.27 KW
61
A vacuum pump is used to drain a flooded mine shaft of 20 deg. C waer. The pump pressure of water at this temperature is 2.34 Kpa. The pump is incapable of lifting the water higher than 16 m. what is the atmospheric pressure.
A. 159.30
62
A submersible, multi-stage, centrifugal deep well pump 260 gpm capacity is installed in a well 27 feet 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 feet. Calculate the diameter of the impeller of this pump in inches if each impeller diameter developed a head of 38 ft.
C. 3.71
63
A fan draws 1.42 m^3 per second of air at a static pressure of 2.54 cm of water through a duct 300 mm diameter and discharges it through a duct of 275 mm diameter. Determine the static fan efficiency if total fan mechanical is 75% and air is measured at 25 deg. C and 760 mm Hg.
B. 53.69%
64
A water coolers uses 50lb/hr of melting ice to cool running water from 80deg F to 42deg F. based on the inside coil area U=110 btu/hr-ft^2-F. Find the gpm of water cooled.
C. 0.38 GPM
65
The charge in a diesel engine consist 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- 60degC, let Rk=14. For constant Cp=1.11 KJ/KG-C, what should be the cut-off ratio in the corresponding ideal cycle ?
D. 2.79
66
The gain of entropy during nonflow process of 5lb of air at 60degF is 0.162 Btu/R. find the V1/V2
B. 0.259
67
An auditorium seating 1500 people is to be maintained at 80degF dry bulb and 65degF wet bulb temp. when outdoor air is a 91degfF dry bulb and 75degF wet bulb. Solar heat loads is 110,000 btu/hr and supply air is at 60degF, determine the amount of air supply.
A. 93,299.17 lb/hr
68
An engine-generated rated 9000 KVA at 80% power factor, 3 phase, 4160 V has an efficiency of 90%. If overall plant efficiency is 28%, what is the heat generated by the fuel?
D. 25,714 KW
69
The indicated thermal efficiency of a two stroke diesel engine is 60%. If the friction power is 15% of the heat generated, determine the brake thermal efficiency of the engine.
B. 45 %
70
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 brake thermal efficiency.
C. 14.64 %
71
A waste heat recovery boiler produces 4.8 Mpa (dry Saturated) steam from 104 deg C feed water. The boiler receives energy from 7 kg/sec of 954 deg C dry air. After passing through the waste heat boiler, the temperature of the air has been reduced to 343 degC. How much steam in kg is produced per second? Note at 4.60 Mpa dry saturated, h = 2796.
C. 1.81
72
Diesel electric plant supplies energy for meralco, during a 24-hour period, the plant consumed 240 gallons of fuel at 28 degC and produced 3930 KW-hr. industrial fuel used is 28 deg API and was purchased at P30 per liter at 15,6 degC. What is the cost of fuel be to produced one KW-hr?
A. 6.87
73
In a gas turbine unit, air enters the combustion chamber at 550 Kpa, 227 degC and 43 m/s. the products of combustion leave the combustor at 511 Kpa, 1004 degC and 180 m/s. liquid fuel enters with a heating value of 43,000 kj/kg. for Fuel-air ratio of 0.0029. what is the combustor efficiency of the unit in percent?
C. 75.38 %
74
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?
D. 835.57 KW
75
A perfect gas has a value of R= 58.8 ft-lb/lb- R and K= 1.26. if 20 Btu are added to 10 lbs of his gas at constant volume when initial temperature is 90 degF find the final temperature.
A. 97 degF
76
Ammonia weighing 22 kgs is confirmed inside a cylinder equipped with a piston has an initial pressure of 413 Kpa at 35 degC if 3200 KJ of heat is added to the ammonia until its final pressure and temperature are 413 Kpa and 100 DegC respectively, what is the amount of work done by the fluid in KJ?
A. 667
77
A tank contains 90 ft^3 of air at a pressure of 350 Psig; of the air is cooled until its pressure and temperature decreases to 200 Psig and 70 DegF respectively, what is the decrease in internal energy?
D.-6232.09 Btu
78
A large mining company was provided with a 3 m^3 of compressed air tank. Air pressure in the tank drops from 700 kpa to 160 kpa while the temperature remains constants at 28 degC, what percentage has the mass of air in the tank been reduced?
D. 78.57
79
A 4 m^3/hr pump delivers water to a pressure tank. At the start, the gage reads 138 Kpa until reads 276 KPa and then pump was shut off. The volume of the tank is 100 liters. At 276 Kpa the water occupied 2/3 of the tank volume. Determine the volume of water that can be taken out until the gage reads 138 Kpa.
B. 34.59 liters
80
A refrigeration plant is rated at 15 tons capacity. How many pounds of air per hour will it cool from 70 to 90 DegF at constant pressure.
B. 37,500 lb/hr
81
An air standard engine has a compression ratio 18 and a cut-off ratio 4. If the intrake air pressure and temperature are 100 kpa and 27deg C, find the work in KJ per kg.
D. 2751
82
Determine the air standard efficiency of an operating on the diesel cycle with clearance of 6% , when the suction pressure is 99.97 kpa and the fuel is injected for 7% of the stroke. Assume k=1.4.
A. 62.11 %
83
Steam at 2Mpa and 250deg C in a rigid cylinder is cooled until the quality is 30%. Find the heat rejected from the cylinder.
C. -1265.02
84
The following coal has the following ultimate analysis by weight: C = 70.5%, H2 = 4.5%, O2 = 6.0%, N2 = 1.0%, S =3.0%, Ash = 11% Moisture = 4% A stocker fired boiler of 195,00 kg/hr steaming capacity used this coal as fuel. Calculate the volume of air in m^3/hr with air at 60 deg. F and 14.7 psia pressure if boiler efficiency is 70% and FE = 1.10
A. 234,019 m^3/hr
85
23.5 kg of steam per second at 5 Mpa and 400 deg. C is produced by a steam generator. The feedwater enters the economizer at 145 deg. C and leaves at 205 deg. C. the steam leaves the boiler drum with a quality of 98%. The unit consumes 3 kg of coal per second as received having a heating value of 25,102 KJ/kg. What would be the overall efficiency of the unit in percent? Steam properties : At 5 Mpa and 400 deg. C: h = 3195.7 KJ/kg at 5 Mpa; hf = 1154.23, hfg = 1640.1 At 205 deg C: hf = 875.04 at 145 deg. C: hf = 1640.1
B. 80.67
86
In an rankine cycle steam enters the turbine at 2.5 Mpa (enthalpies and entropies given) and condenser of 50 kPa (properties are given) what is the thermal efficiency of the cycle?.
A. 25.55%
87
A thermal power plant generates 5 MW and the heat generated by the fuel is 13,000 Kj/sec. if the thermal efficiency is 6.15% , find the power needed for the auxiliaries.
B. 300 Kw
88
Francis Turbine, the Pressure gage leading to the turbine casing reads 380 Kpa. The velocity of water entering a turbine is 0 m/sec, if not hoad of the turbine is 45m. find the distance from center of spiral casing to the ….
A. 3.0 m
89
A turbine has a mechanical efficiency of 93% volumetric efficiency of 95% and total efficiency of 82%. If the effective head is 40m, find the total head.
C. 36.22 m
90
Pelton Type turbine has 25 m head friction loss of 4.5 m. the total coefficient of friction head loss (from morse) is 0.00093 and penstock length of 80 m, what is the penstock diameter?
A. 1,355.73 mm
91
In an 9,000 KW hydro electric power plant the over-all efficiency is 88% and the actual power received by the customer is 110,000 Kw-hrs for that day. What is the secondary power could this plant deliver during the entire day?
B. 80,080 KW
92
Pelton type turbine was installed 30 m below the head gate of the penstock. The head loss due to friction is 12% of the given elevation. The length of penstock is 100 m and coefficient of friction is 0.00093 determine the power output in KW (use morse equation)
D. 34,452
93
Water flows steadily with a velocity of 3.05 m/s in a horizontal pipe having a diameter of 25.24 cm. at one action of the pipe the temperature and pressure of the water are 21 degC and 689.3 Kpa, respectively. At a distance of 304.8 m downstream, the pressure is 516.9 Kpa. What is the friction factor?
C. 0.0307
94
A hydro electric plant having a 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 height of water in the reservoir after the 5-hour period.
D. 2.20 m
95
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 chimney is 63.71 m
B. 0.25 Kpa
96
The actual velocity of gas entering in a chimney is 8 m/sec. the gas temperature is 25 degC with a gas constant of 0.267 kj/kg-K. determine the gas pressure for a mass of gas is 50,00 kg/hr and chimney diameter of 1.39 m
B. 98 Kpa
97
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 DegC and if the atmosphere is at 101.3 Kpa and 28 DegC. What theoretical height of stack in meters is needed when no draft fan are used? Assume that the gas constant for the flue gasses is the same as that for air.
C. 651.10
98
A foundation measures 12 ft x 14 ft x 15 ft. find the number of sacks of cement needed for 1:2:4 mixture
D. 598
99
A rectangular foundation cross-section has a bed plate dimension of 8 ft x 10 ft. the uniform clearance on each side is 1 ft. the height of foundation is 4.5 ft. if the weight of the steel bar reinforcements needed is ½% of weight of foundation, find the weight of steel bars, use concrete density of 2400 Kg/m^3.
B. 183.47