Exam Details
| Subject | Refrigeration System | |
| Paper | ||
| Exam / Course | Diploma in Mechanical Engineering (DMEVI)& B.Tech. MECHANICAL ENGINEERING 1-4 (BTMEVI) | |
| Department | School of Engineering & Technology (SOET) | |
| Organization | indira gandhi national open university | |
| Position | ||
| Exam Date | June, 2016 | |
| City, State | new delhi, |
Question Paper
1.Choose the correct answer from the given four alternatives:
If the thermal efficiency of a Carnot engine is the COP of a Carnot refrigerator is
5
4
6
3
The entropy of a system
can never decrease
can never increase
may increase or decrease
will always remain constant
A vapour absorption refrigeration system works using the
ability of a substance to get easily condensed or evaporated
ability of a vapour to get compressed or expanded
affinity of a substance for another substance
absorptivity of a substance
The thermodynamic process in expansion device of a vapour compression system is considered to be
Throttling
Isothermal expansion
Reversible adiabatic expansion
None of the above
The following refrigerant is considered to be ozone friendly because it does not harm the ozone layer:
R-12
R-22
R-ll
R-134 a
Which statement is not correct
Capillary tube is used as an expansion device in domestic refrigerators.
Reciprocating type compressors are used in small capacity refrigeration systems.
Electrical power is mainly used to run vapour absorption systems.
Electrical power is used to run vapour compression systems.
In milk chilling plants, the usual secondary refrigerant is
ammonia solution
sodium silicate
glycol
brine
What is refrigerating effect Define one tonne of refrigeration.
Describe the vapour absorption refrigeration system with the help of a block diagram.
State the merits and demerits of an air refrigeration system.
A cold storage is to be maintained at 5°C while the surroundings are at 35°C. The heat leakage from the surroundings into the cold storage is estimated to be 29 kW.The actual COP of the refrigeration plant used is one-third that of an ideal plant working between the same temperature. Find the power required (in kW) to drive the plant.
4. A Carnot refrigerator requires 1·3 kW per tonne of refrigeration to maintain a region at a low temperature of -38°C.
Determine:
The COP of the Carnot refrigerator.
Higher temperature of the cycle.
The heat delivered and the COP when this device is used as a heat pump.
5.The capacity of a refrigerator (working on reversed Carnot cycle) is 280 tonnes when operating between -10°C and 25°C.
Determine:
The quantity of ice produced within 24 hours when water is supplied at 20°C.
Minimum power (in kW) required. Take latent heat of ice as 335 kJ/kg.
Explain Bell-Coleman cycle with the help of a neat diagram.
A reversed cycle has a refrigerating COP of 4.
Determine the ratio T1/T2; and
If this cycle is used as a heat pump, determine the COP.
7. The temperature in a refrigerator coil is 267 K and that in the condenser coil is 295 K Assuming that the machine operates on the reversed Carnot cycle, calculate
the COP of the refrigerator,
the refrigerating effect per kW of input work, and
the heat rejected to the condenser.
8. Write short notes on any two of the following:
Steam Jet Refrigeration System
Effect of sub-cooling of liquid on the performance of Vapour Compression System
Transport Refrigeration
If the thermal efficiency of a Carnot engine is the COP of a Carnot refrigerator is
5
4
6
3
The entropy of a system
can never decrease
can never increase
may increase or decrease
will always remain constant
A vapour absorption refrigeration system works using the
ability of a substance to get easily condensed or evaporated
ability of a vapour to get compressed or expanded
affinity of a substance for another substance
absorptivity of a substance
The thermodynamic process in expansion device of a vapour compression system is considered to be
Throttling
Isothermal expansion
Reversible adiabatic expansion
None of the above
The following refrigerant is considered to be ozone friendly because it does not harm the ozone layer:
R-12
R-22
R-ll
R-134 a
Which statement is not correct
Capillary tube is used as an expansion device in domestic refrigerators.
Reciprocating type compressors are used in small capacity refrigeration systems.
Electrical power is mainly used to run vapour absorption systems.
Electrical power is used to run vapour compression systems.
In milk chilling plants, the usual secondary refrigerant is
ammonia solution
sodium silicate
glycol
brine
What is refrigerating effect Define one tonne of refrigeration.
Describe the vapour absorption refrigeration system with the help of a block diagram.
State the merits and demerits of an air refrigeration system.
A cold storage is to be maintained at 5°C while the surroundings are at 35°C. The heat leakage from the surroundings into the cold storage is estimated to be 29 kW.The actual COP of the refrigeration plant used is one-third that of an ideal plant working between the same temperature. Find the power required (in kW) to drive the plant.
4. A Carnot refrigerator requires 1·3 kW per tonne of refrigeration to maintain a region at a low temperature of -38°C.
Determine:
The COP of the Carnot refrigerator.
Higher temperature of the cycle.
The heat delivered and the COP when this device is used as a heat pump.
5.The capacity of a refrigerator (working on reversed Carnot cycle) is 280 tonnes when operating between -10°C and 25°C.
Determine:
The quantity of ice produced within 24 hours when water is supplied at 20°C.
Minimum power (in kW) required. Take latent heat of ice as 335 kJ/kg.
Explain Bell-Coleman cycle with the help of a neat diagram.
A reversed cycle has a refrigerating COP of 4.
Determine the ratio T1/T2; and
If this cycle is used as a heat pump, determine the COP.
7. The temperature in a refrigerator coil is 267 K and that in the condenser coil is 295 K Assuming that the machine operates on the reversed Carnot cycle, calculate
the COP of the refrigerator,
the refrigerating effect per kW of input work, and
the heat rejected to the condenser.
8. Write short notes on any two of the following:
Steam Jet Refrigeration System
Effect of sub-cooling of liquid on the performance of Vapour Compression System
Transport Refrigeration
Other Question Papers
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- Advanced Dynamics Of Machine
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- Engineering Metallurgy
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- Machine Design - I
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- Production Technology - Ii
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- Refrigeration And Air Conditioning
- Refrigeration System
- Robotics
- Safety Engineering
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- Thermal Engineering
- Thermal Engineering - I
- Thermofluid Engineering
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- Tribology
- Turbo Machines
- Unconventional Manufacturing Processes
- Welding Engg.