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This set of Refrigeration and Air conditioning Multiple Choice Questions & Answers (MCQs) focuses on Air - Refrigeration
Q1 | Co-efficient of performance of a Reversed Carnot cycle refrigerator working betweenhigher temperature T2 and lower temperature T1
- will increase with increase in T1 keeping T2 fixed
- will decrease with increase in T1 keeping T2 fixed
- will first increase with increase in T1 and then decrease with increase T1 keeping T2 fixed
- None of the above
Q2 | Bell-Colemann cycle comprises
- two isentropic processes and two adiabatic processes
- two isentropic processes and two isothermal processes
- two isentropic processes and two isobaric processes
- two isentropic processes and two isochoric processes
Q3 | The COP of Carnot Refrigerator is 3 and it produces 1 TR. The work that will be done is equal to
- 70 kJ/min
- 100 kJ/min
- 200 kJ/min
- 210 kJ/min
Q4 | In Bell – Colemann refrigerator for the same temperature range
- COP of dense air system is equal to COP of open air system
- COP of dense air system is lower than COP of open air system
- COP of dense air system is higher than COP of open air system
- COP of dense air system may be higher or lower than COP of open air system depending upon pressure ratio.
Q5 | A Bell-Colemann cycle is
- reversed Carnot Cycle
- reversed Joule Cycle
- reversed Rankine cycle
- None of the above
Q6 | In a refrigeration cycle the heat is rejected by refrigerant at
- expansion valve
- compressor
- condenser
- all the above
Q7 | A reversible refrigerator working between two fixed temperatures
- has the same COP whatever the working substance
- has its COP increased for working substance with high enthalpy of evaporation
- has its COP increased for working substance with higher specific heats
- none of above
Q8 | The air craft system giving Lowest Dry Air Rated Turbine discharge temperature atsupersonic cruising speeds of the plane, is
- Reduced ambient system of Refrigeration
- Boot-strap system of Refrigeration
- Regenerative system of Refrigeration
- Boot strap evaporative system of Refrigeration
Q9 | A reversible refrigerator working between two fixed temperatures
- has the same COP whatever the working substance
- has its COP increased for working substance with high enthalpy of evaporation
- has its COP increased for working substance with higher specific heats
- none of the above
Q10 | Heat is absorbed by the refrigerant, during vapour compression refrigeration cycle in
- Compressor
- Condenser
- Evaporator
- Throttle valve
Q11 | In a simple saturated vapour compression cycle, the refrigerant is in superheated condition
- before entering compressor
- before entering condenser
- before entering throttle valve
- before entering evaporator
Q12 | Sub-cooling is a process of cooling the refrigerant in vapour compression refrigeration system
- after compression
- before compression
- before Throttling
- none of the above
Q13 | The order in which main components of vapour compression refrigeration system are used is
- compressor-evaporator-condenser-throttle valve
- compressor-condenser-evaporator-throttle valve
- compressor-throttle valve- evaporator-condenser
- compressor-condenser- throttle valve- evaporator
Q14 | The oil separator is incorporated in vapour compression refrigeration system
- between evaporator and compressor
- between compressor and condenser
- between condenser and Throttle valve
- between throttle valve and evaporator
Q15 | In vapour compression refrigeration cycle the following data is available Heat rejected in condenser = 65 KW Work done in compressor = 10 kw, then COP( refrigerator) is
- 4.5
- 5.5
- 6.5
- not possible to find with the given data
Q16 | Following results are tabulated for vapour compression refrigeration cycle.Enthalpy at suction = 190 kJ/kgEnthalpy at discharge from compressor = 210 kJ/kgEnthalpy at exit from condenser = 80 kJ/kgCOP of cycle would be
- 3.5
- 4.5
- 5.5
- 6.5
Q17 | For simple saturated vapour compression refrigeration cycle operating between 5°C and 40°C, and the refrigerants being R-11, R-12, R-717 and R-22, the evaporator pressure is lowest for
- R-11
- R-12
- R-717
- R-22
Q18 | For simple saturated vapour compression refrigeration cycle operating between 5°C and 40°C, and the refrigerants being R-11, R-12, R-717 and R-22, the compressor displacement per min per ton of refrigeration is highest for
- R-11
- R-12
- R-717
- R-22
Q19 | With reciprocating compressor in vapour compression refrigeration system, wetcompression is not desirable because
- liquid trapped up in the head of cylinder may damage the compressor valves
- COP of the cycle decreases
- volumetric efficiency of compressor decreases
- mass flow rate per ton of refrigerant increases
Q20 | An ideal refrigerant should have
- low latent heat of vaporization
- high critical temperature
- high boiling point
- high specific volume of vapour
Q21 | The refrigerant leaving throttle valve is
- saturated liquid
- saturated vapour
- superheated vapour
- fraction as saturated vapour and remainder as liquid
Q22 | Freon group of refrigerants
- toxic
- inflammable
- non-toxic and non-inflammable
- highly toxic and inflammable
Q23 | The leaks of refrigerant from a cycle may be detected by
- halide torch test
- sulphur candle test
- soap and water test
- any of the above
Q24 | During compression in a vapour compression cycle the refrigerant is super heated
- work done is increased
- C.O.P is increased
- Work done is reduced
- Refrigerating effect is reduced
Q25 | Heat is rejected by the refrigerant, during vapour compression refrigeration cycle in
- Compressor
- Condenser
- Evaporator
- Throttle valve