Refrigeration And Air Conditioning MCQs Latest – Competitive Mechanical Engineering MCQs
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Latest Mechanical Engineering MCQs
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Latest Refrigeration And Air Conditioning Mcqs
The most occurred mcqs of Refrigeration And Air Conditioning in past papers. Past papers of Refrigeration And Air Conditioning Mcqs. Past papers of Refrigeration And Air Conditioning Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Refrigeration And Air Conditioning Mcqs. The Important series of Refrigeration And Air Conditioning Mcqs are given below:
Which of the following cycles uses air as the refrigerant__________________?
A. Stirling
B. Ericsson
C. Carnot
D. Bell-coleman
E. none of the above
The relative coefficient of performance is_____________________?
A. actual COP/fheoretical COP
B. actual COP x theoretical COP
C. theoretical COP/actual COP
D. 1-actual COP x theoretical COP
E. 1-actual COP/fheoretical COP.
Clapeyron equation is applicable for registration at___________________?
A. saturation point of vapor
B. sublimation temperature
C. saturation point of liquid
D. triple point
E. critical point
In vapor compression cycle, the condition of refrigerant is very wet vapor________________?
A. before passing through the condenser
B. after passing through the condenser
C. after passing through the expansion or throttle valve
D. before entering the expansion valve
E. before entering the compressor
A refrigerant should have _____________________?
Pick up the wrong statement ?
A. high latent heat of vaporisation
B. high boiling point
C. Tow specific heat of liquid
D. higher critical temperature
E. low specific volume of vapour
Clapeyron equation is a relation between___________________?
A. specific volume and enthalpy
B. temperature, pressure and enthalpy
C. temperature and enthalpy
D. temperature, pressure, and specil volume
E. temperature, pressure, specific volur and’enthalpy
In vapor compression cycle, the condition of refrigerant is high pressure saturated liquid________________?
A. before passing through the condenser
B. after passing through the condenser
C. after passing through the expansion or thiottle valve
D. before entering the expansion valve
E. before entering the compressor
The boiling point of ammonia is___________________?
A. -50°C
B. -100°C
C. – 33.3°C
D. 0°C
E. 33.3°C
In S.J. unit, one ton of refrigeration is equal to___________________?
A. 210 kJ/min
B. 420 kJ/min
C. 21 kJ/min
D. 840 kJ/min
E. 105 kJ/min
Allowable pressure on high-pressure side or ammonia absorption system is of the order of_________________?
A. 2-4 bars
B. slightly above atmospheric pressure
C. atmospheric pressure
D. 5-6 bars
E. 7-10 bars
The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases ____________________ ?
A. will be higher
B. will remain unaffected
C. will be lower
D. may be higher or lower depending upon the nature of non-condensable gases
E. unpredictable
The vapor compression refrigerator employs the following cycle_________________?
A. Carnot
B. Rankine
C. Reversed Rankine
D. Brayton
E. Reversed Carnot
The moisture in a refrigerant is removed by___________________?
A. dehumidifier
B. safety relief valve
C. evaporator
D. driers
E. expansion valve
In vapor compression cycle the condition off refrigerant is dry saturated vapor________________?
A. before passing through the condenser
B. after passing through the condenser
C. after passing through the expansion or throttle valve
D. before entering the expansion valve
E. before entering the compressor
In vapour compression cycle, the conditii of refrigerant is saturated liquid________________?
A. after passing through the condenser
B. before entering the expansion valve
C. after passing through the expansion throttle valve
D. before passing through the condensei
E. before entering the compressor
An important characteristic of absorption system of refrigeration is__________________?
A. cooling below 0°C
B. quiet operation
C. noisy operation
D. very little power consumption
E. its input only in the form of heating
Vapor compression refrigeration is some what like ____________________?
A. Rankine cycle
B. Carnot cycle
C. reversed Camot cycle
D. reversed Rankine cycle
E. none of the above
Ammonia-absorption refrigeration cycle requires__________________?
A. very little work input
B. zero work input
C. nearly same work input as for vapour compression cycle
D. maximum work input
E. none of the above
One ton refrigeratiqn corresponds to_________________?
A. 50 kcal/min
B. 80 kcal/min
C. 50 kcal/kr
D. 80 kcal/hr
E. 1000 kcal/day
Production Technology Mcqs
A standard ice point temperature corresponds to the temperature of ___________________?
A. ice at – 4°C
B. water at 0°C
C. solid and dry ice
D. mixture of ice, water and vapour under equilibrium conditions under NTP conditions
E. mixture of ice and water Under equilibrium conditions
In vapour compression cycle the condition of refrigerant is superheated vapour _____________________?
A. before entering the expansion valve
B. before passing through the condenser
C. after passing through the expansion or throttle valve
D. after passing through the condenser
E. before entering the compressor
One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice_________________?
A. in 1 minute
B. in 1 hour
C. in 24 hours
D. in 12 hours
E. in 10 hours
Critical temperature is’ the temperature above which _____________________?
A. a gas will never liquefy
B. water will evaporate
C. a gas will immediately liquefy
D. water will never evaporate
E. none of the above
The COP of a domestic refrigerator___________________?
A. depends upon the make
B. is more than 1
C. is equal to 1
D. is less than 1
E. depends upon the weather conditions
Presence of moisture in a refrigerant affects the working of___________________?
A. compressor
B. evaporator
C. condenser
D. expansion valve
E. heat transfer
Domestic refrigerator working on vapour compression cycle uses the following type of expansion device____________________?
A. electrically operated throttling valve
B. thermostatic valve
C. manually operated valve
D. capillary tube
E. expansion valve.
The domestic refrigerator uses following type of compressor ____________________?
A. centrifugal
B. miniature sealed unit
C. axial
D. piston type reciprocating
E. none of the above
The refrigerant for a refrigerator should have ___________________?
A. high total heat
B. high sensible heat
C. high latent heat
D. low latent heat
E. low sensible heat
Rating of a domestic refrigerator is of the order of__________________?
A. 0.1 ton
B. 10 tons
C. 5 tons
D. 40 tons
E. 100 tons
Refrigeration in aeroplanes usually employs the following refrigerant___________________?
A. CO2
B. Freon-22
C. Freon-11
D. Air
E. none of the above
Air refrigeration operates on_____________________?
A. Reversed Carnot cycle
B. Carnot cycle
C. Rankine cycle
D. Erricson cycle
E. Brayton cycle
For better COP of refrigerator, the pressure range corresponding to temperature in evaporator and condenser must be____________________?
A. small
B. equal
C. high
D. anything
E. under some conditions small and under some conditions high
Air refrigeration cycle is used in ____________________?
A. commercial refrigerators
B. domestic refrigerators
C. air conditioning
D. gas liquefaction
E. such a cycle does not exist
The bank of tubes at the back of domestic refrigerator are _________________?
A. condenser tubes
B. capillary tubes
C. refrigerant cooling tubes
D. evaporator tubes
E. throttling device
The higher temperature in vapour compression cycle occurs at____________________?
A. expansion valve
B. receiver
C. evaporator
D. condenser discharge
E. compressor discharge
The vapor pressure of refrigerant should be_________________?
A. could be anything
B. higher than atmospheric pressure
C. equal to atmospheric pressure
D. lower than atmospheric pressure
E. none of the above
Critical pressure of a liquid is the pressure_________________?
A. above which liquid will remain liquid
B. above which liquid becomes vapour
C. above which liquid becomes gas
D. above which liquid becomes solid
E. at which all the three phases exist together
In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is_____________________?
A. more than 10 kg
B. more than or equal to 3.65 kg
C. less than 2 kg
D. there is no such consideration
E. pone of the above
The value of COP in vapour compression cycle is usually__________________?
A. equal to unity
B. always more than unity
C. always less than unity
D. any one of the above
E. none of the above
Condensing temperature in a refrigerator is the temperature_________________?
A. of cooling medium
B. of evaporator
C. of freezing zone
D. at which refrigerant gas becomes liquid
E. condensing temperature of ice
In refrigerators, the temperature difference between the evaporating refrigerant and the medium being cooled should be_________________?
A. high, of the order of 25°
B. as low as possible (3 to 11°C)
C. any value
D. zero
E. none of the above
In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to___________________?
A. collect liquid refrigerant and prevent it from going to compressor
B. detect liquid in vapour
C. collect vapours
D. superheat the vapour
E. increase refrigeration effect
Accumulators should have adequate volume to store refrigerant charge at least_________________?
A. 25%
B. 10%
C. 50%
D. 75%
E. 100%
A refrigeration cycle operates between condenser temperature of + 27°C and evaporator temperature of- 23°C. The Cannot coefficient of performance of cycle will be_________________?
A. 1.2
B. 0.2
C. 5
D. 6
E. 10
In vapor compression refrigeration system, refrigerant occurs as liquid between_________________?
A. compressor and evaporator
B. condenser and expansion valve
C. expansion valve and evaporator
D. compressor and condenser
E. none of the above
Efficiency of a Carnot engine is given as 80%. If the- cycle direction be reversed, what will be the value of COP of reversed Carnot cycle_________________?
A. 0.8
B. 1.25
C. 0.5
D. 0.25
E. none of the above
Machine Design Mcqs
Aqua ammonia is used as refrigerant in the following type of refrigeration system_________________?
A. direct
B. compression
C. indirect
D. absorption
E. none of the above
If a heat pump cycle operates between the condenser temperature of +27°C and evaporator temperature of – 23°C, then the Carnot COP will be_________________?
A. 1.2
B. 0.2
C. 5
D. 6
E. 10
In a refrigeration cycle, the flow of refrigerant is controlled by___________________?
A. condenser
B. compressor
C. evaporator
D. expansion valve
E. all of the above
The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy-diagram represents_____________________?
A. compression of the refrigerant vapour
B. evaporation of the refrigerant liquid
C. condensation of the refrigerant vapour
D. metering of the refrigerant liquid
E. none of the above
Freon group of refrigerants are___________________?
A. toxic
D. inflammable
C. non-inflammable and toxic
D. non-toxic and inflammable
E. non-toxic and non-inflammable
In vapour compression cycle using NH3 as refrigerant, initial charge is filled at_________________?
A. delivery of compressor
B. suction of compressor
C. high pressure side close to receiver
D. low pressure side near receiver
E. anywhere in the cycle
On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process ________________?
A. takes place at constant temperature
B. involves no change in volume
C. takes place at constant entropy
D. takes place at constant enthalpy
E. takes place at constant pressure
The leaks in a refrigeration system using Freon are detected by____________________?
A. halide torch which on detection produces greenish flame lighting
B. using reagents
C. sulphur sticks which on detection gives white smoke
D. smelling
E. sensing reduction in pressure
Moisture in freon refrigeration system causes________________?
A. high power consumption
B. ineffective refrigeration
C. freezing automatic regulating valve
D. corrosion of whole system
E. breakdown of refrigerant
Super heating in a refrigeration cycle __________________?
A. COP remains unaltered
B. decreases COP
C. increases COP
D. other factors decide COP
E. unpredictable
Hydraulic Mechanics Mcqs
For obtaining high COP, the pressure range of compressor should be_______________?
A. optimum
B. low
C. high
D. any value
E. there is no such criterion
The C.O.P of a refrigeration cycle with increase in evaporator temperature, keeping condenser temperature constant, will______________________?
A. increase
B. remain unaffected
C. decrease
D. may increase or decrease depending on the type of refrigerant used
E. unpredictable
Most of the domestic refrigerators work on the following refrigeration system _________________?
A. vapour compression
B. carnot cycle
C. vapour absorption
D. electrolux refrigerator
E. dual cycle
Reducing suction pressure in refrigeration cycle_________________?
A. reduces weight displaced by piston
B. increases power required per ton of refrigeration
C. lowers compressor capacity because vapour is lighter
D. lowers evaporation temperature
E. all of the above
The refrigeration effect in a dry evaporator compared to flooded evaporator in a similar plant is_________________?
A. more
B. same
C. less
D. more or less depending on ambient conditions
E. unpredictable
Which of the following refrigerants has lowest freezing point_______________?
A. Freon-12
B. C02
C. NH3
D. Freon-22
E. S02
The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P_____________________?
A. more
B. equally
C. less
D. unpredictable
E. none of the above
The COP of a vapor compression plant in comparison to vapor absorption plant is ________________?
A. more
B. same
C. less
D. more/less depending on size of plant
E. unpredictable
The evolution of heat of solution takes place in ammonia absorption plant when _____________________?
A. ammonia vapour goes into solution
B. ammonia vapour is driven out of solution
C. weak solution mixes with strong solution
D. lithium bromide mixes with ammonia
E. lithium bromide is driven out of solution
The C.O.P. of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperature constant, will__________________?
A. increase
B. remain unaffected
C. may increase or decrease depending on the type of refrigerant used
D. decrease
E. unpredictable
Cooling water is required for following equipment in ammonia absorption plant__________________?
A. evaporator
B. condenser
C. absorber
D. condenser and absorber
E. condenser, absorber and separator (rectifier)
The general rule for rating refrigeration systems (excepting for C02 system) is to approximate following h.p. per ton of refrigeration__________________?
A. 0.5 to 0.8 h.p. per ton of refrigeration
B. 0.1 to 0.5 h.p. per ton of refrigeration
C. 1 to 2 h.p. per ton of refrigeration
D. 2 to 5 h.p. per ton of refrigeration
E. 5 to 10 h.p. per ton refrigeration
Vertical lines on pressure-enthalpy chart show constant_______________?
A. temperature lines
B. pressure lines
C. total heat lines
D. entropy lines
E. volume lines
The coefficient of performance is the ratio of the refrigerant effect to the_________________?
A. work done by compressor
B. heat of compression
C. enthalpy increase in compressor
D. all of the above
E. none of the above
Under-cooling in a refrigeration cycle_________________?
A. increases COP
B. COP remains unaltered
C. decreases COF
D. other factors decide COP
E. unperdictable
The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is_________________?
A. bigger
B. equal
C. smaller
D. smaller/bigger depending on capacity
E. unpredictable
The advantage of dry compression is that________________?
A. it permits complete evaporation in the evaporator
B. it permits higher speeds to be used
C. it results in high volumetirc and mechanical efficiency
D. all of the above
E. none of the above
For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphere is high, then_________________?
A. smaller cabinet should be used
B. bigger cabinet should be used
C. perfectly tight vapour seal should be used
D. refrigerant with lower evaporation temperature should be used
E. refrigerant with high boiling point must be used
One ton of the refrigeration is_________________?
A. the cooling effect produced by melting 1 ton of ice
B. the standard unit used in refrigeration problems
C. the refrigeration effect to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours
D. the refrigeration effect to produce 1 ton of ice at NTP conditions
E. the refrigeration effect to produce 1 ton of ice in 1 hour time
Short horizontal lines on pressure-enthalpy chart show__________________?
A. constant pressure lines
B. constant total heat lines
C. constant temperature lines
D. constant entropy lines
E. constant volume lines
Ammonia is __________________?
A. non-inflammable
B. non-toxic
C. toxic and non-inflammable
D. highly toxic and inflammable
E. none of the above
Mass flow ratio of NH3 in comparison to Freon-12 for same refrigeration load and same temperature limits is of the order of___________________?
A. 9 : 1
B. 1 : 9
C. 1 : 1
D. 1 : 3
E. 3 : 1
Where does the lowest temperature occur in a vapour compression cycle ?
A. compressor
B. evaporator
C. condenser
D. expansion valve
E. receiver
Engineering Materials Mcqs
A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure of about 67 kg/cm. The refrigerant used is________________?
A. Freon
B. Carbon dioxide
C. Ammonia
D. Brine
E. Hydrocarbon refrigerant
Highest pressure encountered in a refrigeration system should be________________?
A. much above critical pressure
B. much below critical pressure
C. critical pressure of refrigerant
D. near critical pressure
E. there is no such restriction
If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. of compressor required will be________________?
A. less
B. more
C. same
D. more/less depending on rating
E. unpredictable
Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system ?
A. strong solution to ammonia vapour
B. weak solution to strong solution
C. strong solution to weak solution
D. ammonia vapour to weak solution
E. ammonia vapour to strong solution
Which of the following is not a desirable property of a refrigerant_________________?
A. low boiling point
B. high triiscibility with oil
C. good electrical conductor
D. large latent heat
E. non-inflammable
At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant_________________?
A. remains same
B. increases
C. decreases
D. depends on other factors
E. none of the above
Formation of frost on evaporator in refrigerator ________________?
A. results in loss of heat due to poor heat transfer
B. is immaterial
C. increases heat transfer rate
D. can be avoided by proper design
E. decreases compressor power
In a refrigeration system, heat absorbed in comparison to heat rejected is_________________?
A. same
B. less
C. more
D. more for small capacity and less for high capacity
E. less for small capacity and more for high capacity
One of the purposes of sub-cooling the liquid refrigerant is to________________?
A. increase cooling effect
B. reduce compressor discharge temperature
C. reduce compressor overheating
D. ensure that only liquid and not the vapour enters the expansion (throttling) valve
E. none of the above
Highest temperature encountered in refrigeration cycle should be________________?
A. above critical temperature
B. near critical temperature of refrigerant
C. at critica. temperature
D. much below critical temperature
E. could be anywhere
Absorption system normally uses the following refrigerant___________________?
A. Freon-22
B. Freon-11
C. C02
D. S02
E. ammonia
In a vapor compression cycle, the refrigerant immediately after expansion valve is___________________?
A. sub-cooled liquid
B. liquid
C. saturated liquid
D. wet vapour
E. dry vapour
Choose the correct statement?
A. Precooling and subcooling bf refrigerant are same
B. If operating temperature of system is low, then refrigerant with low boiling point should be used
C. A refrigerant should have low latent heat
D. Superheat and sensible heat of a. refrigerant are same
E. Refrigerant is inside the lubes in case of a direct-expansion chiller
Choose the wrong statement ?
A. Temperature of medium being cooled must be below that of the evaporator
B. frost on evaporator reduces heat transfer
C. All solar thermally operated absorption systems are capable only of intermittent operation
D. Refrigerant leaves the condenser as liquid
E. refrigerant is circulated in a refrigeration system to transfer heat
Pick up the incorrect statement?
A. lithium bromide plant can’t operate below 0°C
B. lithium bromide used in vapour absorption cycle is nonvolatile
C. a separator is used in lithium bromide plant to remove the unwanted water vapour by condensing
D. concentration of solution coming out of lithium bromide generator is more in comparison to that entering the generator
E. weak solution in liquid heat exchanger gives up heat to the strong solution