Explore topic-wise MCQs in Mechanical Engineering Questions.

This section includes 94 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.

1.

Accumulators should have adequate volume to store refrigerant charge at least_________________?
A. 10%
B. 25%
C. 50%
D. 75%
E. 100%
Answer» D. 75%
Discussion
2.

The vapor compression refrigerator employs the following cycle_________________?
A. Rankine
B. Carnot
C. Reversed Rankine
D. Brayton
E. Reversed Carnot
Answer» F.
Discussion
3.

The relative coefficient of performance is_____________________?
A. actual COP/fheoretical COP
B. theoretical COP/actual COP
C. actual COP x theoretical COP
D. 1-actual COP x theoretical COP
E. 1-actual COP/fheoretical COP.
Answer» B. theoretical COP/actual COP
Discussion
4.

Which of the following cycles uses air as the refrigerant__________________?
A. Ericsson
B. Stirling
C. Carnot
D. Bell-coleman
E. none of the above
Answer» E. none of the above
Discussion
5.

In vapor compression cycle, the condition of refrigerant is very wet vapor________________?
A. after passing through the condenser
B. before passing through the condenser
C. after passing through the expansion or throttle valve
D. before entering the expansion valve
E. before entering the compressor
Answer» F.
Discussion
6.

Clapeyron equation is applicable for registration at___________________?
A. saturation point of vapor
B. saturation point of liquid
C. sublimation temperature
D. triple point
E. critical point
Answer» B. saturation point of liquid
Discussion
7.

A refrigerant should have _____________________?
Pick up the wrong statement ?
A. Tow specific heat of liquid
B. high boiling point
C. high latent heat of vaporisation
D. higher critical temperature
E. low specific volume of vapour
Answer» C. high latent heat of vaporisation
Discussion
8.

The moisture in a refrigerant is removed by___________________?
A. evaporator
B. safety relief valve
C. dehumidifier
D. driers
E. expansion valve
Answer» E. expansion valve
Discussion
9.

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 be lower
C. will remain unaffected
D. may be higher or lower depending upon the nature of non-condensable gases
E. unpredictable
Answer» B. will be lower
Discussion
10.

Ammonia-absorption refrigeration cycle requires__________________?
A. very little work input
B. maximum work input
C. nearly same work input as for vapour compression cycle
D. zero work input
E. none of the above
Answer» B. maximum work input
Discussion
11.

In vapor compression cycle the condition off refrigerant is dry saturated vapor________________?
A. after passing through the condenser
B. before passing through the condenser
C. after passing through the expansion or throttle valve
D. before entering the expansion valve
E. before entering the compressor
Answer» F.
Discussion
12.

Clapeyron equation is a relation between___________________?
A. temperature, pressure and enthalpy
B. specific volume and enthalpy
C. temperature and enthalpy
D. temperature, pressure, and specil volume
E. temperature, pressure, specific volur and’enthalpy
Answer» F.
Discussion
13.

In vapour compression cycle, the conditii of refrigerant is saturated liquid________________?
A. after passing through the condenser
B. before passing through the condensei
C. after passing through the expansion throttle valve
D. before entering the expansion valve
E. before entering the compressor
Answer» B. before passing through the condensei
Discussion
14.

Vapor compression refrigeration is some what like ____________________?
A. Carnot cycle
B. Rankine cycle
C. reversed Camot cycle
D. reversed Rankine cycle
E. none of the above
Answer» F.
Discussion
15.

One ton refrigeratiqn corresponds to_________________?
A. 50 kcal/min
B. 50 kcal/kr
C. 80 kcal/min
D. 80 kcal/hr
E. 1000 kcal/day
Answer» B. 50 kcal/kr
Discussion
16.

An important characteristic of absorption system of refrigeration is__________________?
A. noisy operation
B. quiet operation
C. cooling below 0°C
D. very little power consumption
E. its input only in the form of heating
Answer» C. cooling below 0°C
Discussion
17.

In vapor compression cycle, the condition of refrigerant is high pressure saturated liquid________________?
A. after passing through the condenser
B. before passing through the condenser
C. after passing through the expansion or thiottle valve
D. before entering the expansion valve
E. before entering the compressor
Answer» E. before entering the compressor
Discussion
18.

A standard ice point temperature corresponds to the temperature of ___________________?
A. water at 0°C
B. ice at – 4°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
Answer» F.
Discussion
19.

In S.J. unit, one ton of refrigeration is equal to___________________?
A. 210 kJ/min
B. 21 kJ/min
C. 420 kJ/min
D. 840 kJ/min
E. 105 kJ/min
Answer» B. 21 kJ/min
Discussion
20.

The boiling point of ammonia is___________________?
A. -100°C
B. -50°C
C. – 33.3°C
D. 0°C
E. 33.3°C
Answer» D. 0°C
Discussion
21.

Allowable pressure on high-pressure side or ammonia absorption system is of the order of_________________?
A. atmospheric pressure
B. slightly above atmospheric pressure
C. 2-4 bars
D. 5-6 bars
E. 7-10 bars
Answer» E. 7-10 bars
Discussion
22.

Which of the following is not a desirable property of a refrigerant_________________?
A. high triiscibility with oil
B. low boiling point
C. good electrical conductor
D. large latent heat
E. non-inflammable
Answer» D. large latent heat
Discussion
23.

Highest pressure encountered in a refrigeration system should be________________?
A. critical pressure of refrigerant
B. much below critical pressure
C. much above critical pressure
D. near critical pressure
E. there is no such restriction
Answer» C. much above critical pressure
Discussion
24.

If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. of compressor required will be________________?
A. same
B. more
C. less
D. more/less depending on rating
E. unpredictable
Answer» C. less
Discussion
25.

Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system ?
A. strong solution to weak solution
B. weak solution to strong solution
C. strong solution to ammonia vapour
D. ammonia vapour to weak solution
E. ammonia vapour to strong solution
Answer» C. strong solution to ammonia vapour
Discussion
26.

Air refrigeration operates on_____________________?
A. Carnot cycle
B. Reversed Carnot cycle
C. Rankine cycle
D. Erricson cycle
E. Brayton cycle
Answer» F.
Discussion
27.

At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant_________________?
A. decreases
B. increases
C. remains same
D. depends on other factors
E. none of the above
Answer» C. remains same
Discussion
28.

For better COP of refrigerator, the pressure range corresponding to temperature in evaporator and condenser must be____________________?
A. small
B. high
C. equal
D. anything
E. under some conditions small and under some conditions high
Answer» B. high
Discussion
29.

Air refrigeration cycle is used in ____________________?
A. domestic refrigerators
B. commercial refrigerators
C. air conditioning
D. gas liquefaction
E. such a cycle does not exist
Answer» E. such a cycle does not exist
Discussion
30.

The bank of tubes at the back of domestic refrigerator are _________________?
A. condenser tubes
B. evaporator tubes
C. refrigerant cooling tubes
D. capillary tubes
E. throttling device
Answer» B. evaporator tubes
Discussion
31.

The higher temperature in vapour compression cycle occurs at____________________?
A. receiver
B. expansion valve
C. evaporator
D. condenser discharge
E. compressor discharge
Answer» F.
Discussion
32.

In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is_____________________?
A. less than 2 kg
B. more than or equal to 3.65 kg
C. more than 10 kg
D. there is no such consideration
E. pone of the above
Answer» C. more than 10 kg
Discussion
33.

Critical pressure of a liquid is the pressure_________________?
A. above which liquid will remain liquid
B. above which liquid becomes gas
C. above which liquid becomes vapour
D. above which liquid becomes solid
E. at which all the three phases exist together
Answer» B. above which liquid becomes gas
Discussion
34.

The vapor pressure of refrigerant should be_________________?
A. lower than atmospheric pressure
B. higher than atmospheric pressure
C. equal to atmospheric pressure
D. could be anything
E. none of the above
Answer» C. equal to atmospheric pressure
Discussion
35.

The value of COP in vapour compression cycle is usually__________________?
A. always less than unity
B. always more than unity
C. equal to unity
D. any one of the above
E. none of the above
Answer» C. equal to unity
Discussion
36.

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. superheat the vapour
D. collect vapours
E. increase refrigeration effect
Answer» B. detect liquid in vapour
Discussion
37.

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. zero
D. any value
E. none of the above
Answer» C. zero
Discussion
38.

In vapor compression refrigeration system, refrigerant occurs as liquid between_________________?
A. condenser and expansion valve
B. compressor and evaporator
C. expansion valve and evaporator
D. compressor and condenser
E. none of the above
Answer» D. compressor and condenser
Discussion
39.

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. 1.25
B. 0.8
C. 0.5
D. 0.25
E. none of the above
Answer» E. none of the above
Discussion
40.

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. 0.2
B. 1.2
C. 5
D. 6
E. 10
Answer» D. 6
Discussion
41.

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. 0.2
B. 1.2
C. 5
D. 6
E. 10
Answer» E. 10
Discussion
42.

Aqua ammonia is used as refrigerant in the following type of refrigeration system_________________?
A. compression
B. direct
C. indirect
D. absorption
E. none of the above
Answer» E. none of the above
Discussion
43.

One of the purposes of sub-cooling the liquid refrigerant is to________________?
A. reduce compressor overheating
B. reduce compressor discharge temperature
C. increase cooling effect
D. ensure that only liquid and not the vapour enters the expansion (throttling) valve
E. none of the above
Answer» E. none of the above
Discussion
44.

Critical temperature is’ the temperature above which _____________________?
A. a gas will never liquefy
B. a gas will immediately liquefy
C. water will evaporate
D. water will never evaporate
E. none of the above
Answer» B. a gas will immediately liquefy
Discussion
45.

One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice_________________?
A. in 1 hour
B. in 1 minute
C. in 24 hours
D. in 12 hours
E. in 10 hours
Answer» D. in 12 hours
Discussion
46.

The COP of a domestic refrigerator___________________?
A. is less than 1
B. is more than 1
C. is equal to 1
D. depends upon the make
E. depends upon the weather conditions
Answer» C. is equal to 1
Discussion
47.

In vapour compression cycle the condition of refrigerant is superheated vapour _____________________?
A. after passing through the condenser
B. before passing through the condenser
C. after passing through the expansion or throttle valve
D. before [entering the expansion valve
E. before entering the compressor
Answer» C. after passing through the expansion or throttle valve
Discussion
48.

The refrigerant for a refrigerator should have ___________________?
A. high sensible heat
B. high total heat
C. high latent heat
D. low latent heat
E. low sensible heat
Answer» D. low latent heat
Discussion
49.

Domestic refrigerator working on vapour compression cycle uses the following type of expansion device____________________?
A. electrically operated throttling valve
B. manually operated valve
C. thermostatic valve
D. capillary tube
E. expansion valve
Answer» E. expansion valve
Discussion
50.

Presence of moisture in a refrigerant affects the working of___________________?
A. compressor
B. condenser
C. evaparator
D. expansion valve
E. heat transfer
Answer» E. heat transfer
Discussion