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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 1m^3 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 40°C.
D. 9.47
5
Compute the air flow in ft^3/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 9kg.
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 16psig.
A . 0.286ft
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. 2.55m
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 10⁶
15
Air at 10 deg. C and 80 Kpa enters a diffuser of a jet engine steadily with a diffuser is 0.40 m².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. P49.59
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 4.2KJ/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=1.0KJ/kg-K
C. 3.072 KW
20
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 generated during this process.
C. 4.32 KJ/K
21
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
22
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
23
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
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 generated by the windmill.
B. 70 KW
25
Consider a large furnace that can supply heat at temperature of 2000 deg. Rat a steady rate of 3000 Btu/s. Determine the exergy of this energy. Assume an environment temperature of 77 deg. F.
Β. 2315.19 KW
26
A heat engine receives heat from a deg. K. the power output of the source at 1200 deg. K at rate of 500 KJ/s and rejects the waste heat to a medium at 300 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. Cand 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 of6 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 of the recommend 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 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 gas at 4 atm and 40 deg. C. Now a valve is opened, and half of an ideal of mass of the gas is allowed to escape. If the final pressure in the tank is 1.5 atm. final temperature in the tanks The 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) trip at a location where the after the atmospheric pressure is 90 kpa. If the temperature of the air in the tire 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 evaporates in 30 min. the rate of heat stainless steel pan on an electric range. It is observed that 2 kg of liquid water 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 transfer coefficient is 6 W/m^2 with the person are 1.6 m^2 and 29 deg. C respectively, and the convection heat transfer coefficient is 6 W m² with the emissivity factor of 0.95
D. 168.1 watts
37
Water is boiling sea 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. 730K
39
At 35% solution leaves the absorber The heat removed from the absorber by ammonia is superheated by 10deg. Find the pound per pound of ammonia gas from the evaporating coils. and 30% solution enters the absorber. cooling water is 547.6
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 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^{\wedge}3/kg~a 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 4m³/s. if r1=0. , beta1-110deg, and the blade height B is 10cm, what should be the guide angle al 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/m³
D. 9.28 m/sec
45
A fan delivers 5.7 m³/ 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 m³/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. 63.69in
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 deg C 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 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 he volume of air at suction.
D . 571.62m^3/hr
51
An air compressor has a suction volume of 0.35 m³/s at 97 kpa and discharge to 650 kpa. How much power is saved by the compressor if there are two stages.
D. 11.58 KW
52
A two stage air compressor has an intercooler pressure of 4 kg/cm². What is the discharge pressure if suction pressure is 1 kg/cm²
D. 16 kg/cm^2
53
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
54
Water-jacketed air compressor handles 0343 m^3/s of air entering at 96.5Kpa and 21 deg. C and leaving at 480 Кра and 132 deg. C; 10.9 kg/h of cooling water enters the jacket at 15 deg. Cand leaves at 21 deg. C. Determine the compressor brake power?
B. 62.650 kw
55
A double suction centrifugal pumps delivers 20 ft^{\wedge}3/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
56
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