QUIZ 3 —-------------------------------------------------E
The amount of heat absorbed in the evaporator, which is the same as the amount of heat removed
from the space to be cooled. Refrigerating effect
A Carnot refrigeration cycle absorbs heat at -15°C and rejects it at 45°C. Calculate the COP. 4.30
A refrigerating unit of one ton capacity can remove: 200
A Carnot refrigeration cycle absorbs heat at -15°C and rejects it at 45°C. If the cycle is absorbing 20
kW at -15°C, how much power is required: 4.65kW
A Carnot refrigeration cycle absorbs heat at -15°C and rejects it at 45°C. If a Carnot heat pump
operates between the same temperatures, what is the PF? 5.30
This is the component in the refrigeration circuit where heat is removed from the substance being
cooled, air or water in the case of air conditioning.condenser
A refrigeration plant is rated at 25 tons capacity. How many pounds of air per hour will it cool from 75
to 95°F at constant pressure? 62,500lb/hr
Where is lithium bromide used in a refrigeration system? Absorbers
Which of the following would not cause high suction pressure? Suction valve not adjusted properly
Milk must be received and cooled from 98°F to 37°F in 5 hours. If 4500 gallons of fresh milk received
having SG of 1.05 and constant pressure specific heat of 0.93 Btu per lb-°F, find the refrigeration
capacity. 37.28
What effect would a refrigeration overcharge have on the system? Head pressure would increase
An industrial plant requires to cool 250 gal/min of water from 25°C to 8°C. Determine the tons of
refrigeration required. 319.25TR
It is the designation for other refrigerants that are chlofluorocarbons but cause little or no ozone
destruction. HCFC or HFC
A refrigeration system consumed 28,800 kW-hr per month of energy. There is 20% of energy lost
due to the cooling system of the compressor and the motor efficiency is 90%. If the COP of the
system is 6, find the refrigerating capacity. 49.15TR
The amount of heat absorbed in the evaporator, which is the same as the amount of heat removed
from the space to be cooled. Refrigerating effect
A refrigeration system operates on the reversed Carnot cycle. The highest temperature of the
refrigerant in the system is 120°F and the lower temperature is 10°F. The capacity is to be 20 tons.
Determine the heat rejected from the system in Btu/min. 4936
A Carnot refrigeration cycle absorbs heat at -15°C and rejects it at 45°C. If the cycle is absorbing 20
kW at -15°C, how much power is required? 4.65kW
This is the component in the refrigeration circuit where heat is removed from the substance being
cooled, air or water in the case of air conditioning. Evaporator
QUIZ 4 —--------------------------------------------------------------------------head pressure would increase
Consider two Carnot hear engines operating in series. The first engine receives heat from the
reservoir at 2400 K and rejects the waste heat to another reservoir at temperature T. The second
engine receives heat by the first one, convert some of it to work, and rejects the rest to a reservoir at
300 K. If thermal efficiencies of both engines are the same, determine the temperature T.849K
Guys wait ito sagot lahat
Baka maulit eh
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A Carnot engine receives 180 Btu of heat from a hot reservoir at 700°F and rejects 49 Btu of
heat. Calculate the temperature of the cold reservoir. -144.22°
The dividing point between the high-pressure and low-pressure sides of the refrigeration cycle occurs
at the: expansion valve
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 efficiency 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. P 49.59
The ice making capacity is always: directly proportional to the refrigerating effect
An odorless refrigerant, its boiling point varies over a wide range of temperature: Freon 22
A certain gas at 101.325 kPa and 10 C whose volume is 2.83 m^3 capacity. Before admission, the
storage vessel contained gas at a pressure and temperature of 137.8 kPa and 26 C; after admission, the
pressure increased to 1171.8 kPa. What should be the final temperature of the gas in the vessel in
Kelvin? 314.2
7. Consider two Carnot hear engines operating in series. The first engine receives heat from the reservoir
at 2400 K and rejects the waste heat to another reservoir at temperature T. 849 K
8. · A 23-ton refrigeration system has a heat rejected of 100 kW. Find the energy efficiency ratio of
the system. 14.42
9.
10. A Carnot refrigeration system operates at Tmax/Tmin = 1.5. Find the kW per ton of
refrigeration. 1.91
11. A Carnot refrigeration system operates at Tmax/Tmin = 1.5. Find the kW per ton of
refrigeration. 1.76
12. 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 efficiency 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. P 49.59
13.
1.91
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1.91
Brine enters a circulating brine cooler at the rate of 60m³/hr at -8°C and leaves at -18°C. Specific
heat of brine is 1.075 kJ/kg-K and specific gravity of 1.12. Determine the tons of refrigeration. 56.9
The difference in temperature between the water leaving the evaporator and evaporator temperature
is 4°C. If the temperature of water leaving is 35°F, what is the evaporator temperature? -2C
A 23-ton refrigeration system has a heat rejected of 100 kW. Find the energy efficiency ratio of the
system. 14.42
If the energy efficiency ratio of the refrigeration system is 12.6, what is the COP of the system? 3.69
3.6
Air is compressed polytropically so that the quantity pV^1.4 is constant. If 0.02 m³ of air at
atmospheric pressure and 4 °C are compressed to a gage pressure of 405 kPa, determine the final
temperature of the air in °C. 165.64 Lalagay ko pa lang boss dan hahaha
A refrigeration plant is rated at 15 tons capacity. How many pounds of air per hour will it cool from
70°F to 90°F at constant temperature 37,500 lb/hr salamat
An elastic sphere containing gas at 120 kPa has a diameter of 1-m. Heating the sphere causes it to
expand to a diameter of 1.3-m. During the process the pressure is proportional to the sphere
diameter. Calculate the work done by the gas in kJ. 87.5
Ano dto? Hehe dalawa kasi sagot
A Carnot refrigeration system operates at Tmax/Tmin = 1.5. Find the kW per ton of
refrigeration. 1.76
A refrigeration plant is rated at 15 tons capacity. How many pounds of air per hour will it cool
from 70°F to 90°F at constant temperature? 37,500 lb/hr
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Quiz 5 —---------------------------------------------------------
A Freon 22 air conditioning under standard 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 capacity if the refrigerating effect is 164 kJ/kg. From the table for R22 the specific
volume at the compressor entrance is 40.46 L/kg. 27.4 tr
The specific measurement of moisture content in air: specific humidity
An industrial plant requires to cool 120 gal/min of water from 20°C to 5°C. Determine the tons of
refrigeration required. 135 TR
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The change of enthalpy in the condenser is 150of surrounding air is 25°C and efficiency is 65%. If mass
of water leaving the tower
0 kJ/kg. The temperature change of water is 8°C and the refrigerant flow is 0.13 kg/sec. Determine
the gpm of water required for cooling. 92gpm
The amount water carried by air in a cooling tower is 15 lb/min. The change in humidity ratio in outlet
and inlet is 0.025 lb/lb. Determine the volume flow of air needed if specific volume is 13 ft³/lb:7800
ft³/min
An air conditioning system is used to maintain a house at 75 F when the temperature outside is 95 F.
The house is gaining the heat through the walls and windows at a rate of 1250 Btu/min, and the heat
generation rate within the house from people, lights, and appliances amounts 350 Btu/min.
Determine the minimum power input required for this air conditioning system. Ans: 1.41hp
The total heat load and latent heat load of theater is 150 kW and 60 kW, respectively. Supply air is at
15°C and has a mass of 9 kg/sec. Determine the temperature to be maintained in the theater. 25 C
The change of temperature entering the cooling tower and wet bulb temperature of surrounding air is
25°C and efficiency is 65%. If mass of water leaving the tower is 10 kg/sec, determine the heat
carried by air. 680 kW
The power required to drive the compressor in a Carnot refrigeration is 50 hp. It operates between
-5°C and 40°C. Determine the tons of refrigeration. 63Tr
When100 kg/min of outside air at 32°C dry bulb and 200 kg/min recirculated air at 22°C dry bulb are
mixed with an air conditioning system, the resulting dry bulb temperature will be::25.33
The approach and efficiency of cooling tower is 10°C and 60%, respectively. If temperature of water
leaving the tower is 37°C, what is the temperature of water entering? 52C
Outside air of an air conditioning system is 25% of recirculated air. Determine the mass of outside air
if mass of supply air is 15 kg/sec. 3kg/s
A refrigeration system operates on an ideal vapor-compression using R-12 with an evaporator
temperature of -30°C and a condenser exit temperature of 49.3°C and requires a 74.6 kW motor to
drive the compressor. What is the capacity of the refrigerator in TOR? Enthalpy of condenser
entrance = 382 kJ/kg, exit = 248.15; at evaporator entrance = 248.15, exit = 338.14. 43.1
When a man returns to his well-sealed house on a summer day, he finds that the house is at 32 C.
He truns on the air conditioner, which cools the entire house to 20 C in 15 minutes. If the COP of the
air conditioner system is 2.5, determine the power drawn by the air conditioners. Assume the entire
mass within the house is equivalent to 800 kg of air for which the specific heat is 0.72 kJ/kg-C.
3.07C
The amount water carried by air in a cooling tower is 15 lb/min. The change in humidity ratio in outlet
and inlet is 0.025 lb/lb. Determine the volume flow of air needed if specific volume is 13 ft³/lb. Meron
na yan sa taas mahaba sagot eh hahaha 7800
An auditorium seating 1500 people is to 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. Solat heat load is 110,000 Btu/hr and air
supply is at 60 F, determine the amount of supply air. . 93,229.17 lb/hr
When a man returns to his well-sealed house on a summer day, he finds that the house is at 32 C.
He truns on the air conditioner, which cools the entire house to 20 C in 15 minutes. If the COP of the
air conditioner system is 2.5, determine the power drawn by the air conditioners. Assume the entire
mass within the house is equivalent to 800 kg of air for which the specific heat is 0.72 kJ/kg-C.
3.07Kw
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Quiz 6 —---------------------------------------------------------------------------The flywheel of a rope brake is 1.22-m diameter and the rope is 24 mm diameter. When the engine
is running at 250 rpm, the load on the brake is 480-N on one end of the rope and 84-N on the other
end. Calculate the brake power 6.45Kw
A hydro-electric power plant consumes 52,650,000 kW-hrs per annum. Expected flow is 1665
m³/min and over-all efficiency is 65%. What is the net head? 34m
The cylinder diameters of an eight-cylinder, single acting, four-stroke diesel engine are 750-mm and
the stroke is 1125-mm. The indicated mean effective pressure in the cylinders is 586 kPa when the
engine is running at 110 rpm. Calculate the indicated power. 2135.82KW
The heat generated by fuel is 2500 kW. If the jacket water loss is 30%, determine the mass of water
circulated in the engine if the temperature rise is 8°C. 22.4 kg/s22
Determine the piston speed of a 250mm x 300mm diesel engine running at 1200 rpm 12m/s.
What is the power developed in the cylinder if indicated thermal efficiency is 44%? The engine uses
0.05 kg/s fuel with heating value of 44,000 kJ/kg. 968KW
The penstock of hydro-electric plant is 0.5x0.5 m with velocity of 5.5 m/sec has a head of 20 m.
What is the output of the turbine if turbine efficiency is 87%? 234.70 kW
What is the turbine output of 100 m head and delivering 1 m³/sec in a hydro-electric power plant if
turbine efficiency is 88%? 863.28
Determine the piston speed of a 250mm x 300mm diesel engine running at 1200 rpm. 12 m/s
A hydraulic turbine receives water from a reservoir at an elevation of 100 m above it. What is the
minimum water flow in kg/s to produce a steady turbine output of 50 MW. 50968
What is the speed of a 30-cm x 35-cm diesel engine running at 1100 rpm? 12.83m/s
The flywheel of a rope brake is 1.22-m diameter and the rope is 24 mm diameter. When the engine
is running at 250 rpm, the load on the brake is 480-N on one end of the rope and 84-N on the other
end. Calculate the brake power. 6.45KW
In a hydro-electric power plant, the tail water level fixes 480 m. The net head is 27 m and head loss
is 4% of the gross head. What is the head water elevation? 508.12 m
Determine the speed of a 6-pole generator of 60 hz. 1200rpm
The difference in elevation between the surface of the water in a storage reservoir and the intake to
a turbine was 140 ft. During a test, the pressure head at the latter point was 130 ft and the discharge
was 50 cfs. The inside diameter of the penstock was 35 inches. What was the efficiency of the
pipeline?
93.48%
A 750 kW diesel electric plant has a brake thermal efficiency of 34%. If the heat generated by the
fuel is 9,000,000 kJ/hr, what is the generator efficiency? 88.23%
A hydraulic turbine receives water from a reservoir at an elevation of 100 m above it. What is the
minimum water flow in kg/s to produce a steady turbine output of 50 MW. 50968
The heat generated by fuel is 2500 kW. If the jacket water loss is 30%, determine the mass of water
circulated in the engine if the temperature rise is 8°C. 22.4kg/s
A 50 Bhp blast furnace engine uses fuel with 10 ft³/Bhp-hrs. The heating value of gas is 33,500
kJ/m³. Determine the brake thermal efficiency. 28.31%
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