Vapour Compression Refrigeration MCQs

Q1 | Wet compression vapour compression refrigeration cycle means

Vapour compression takes place in wet region

Vapour compression in dry region, but evaporation in wet region

vapour compression in wet region, but leaves in superheated region

None of the above

Q2 | 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 highest for

R-11

R-12

R-717

R-22

Q3 | With reciprocating compressor in vapour compression refrigeration system, wet compression 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

Q4 | An ideal refrigerant should have

low latent heat of vaporization

lower critical temperature

lower boiling point

high specific volume of vapour

Q5 | During compression in a vapour compression cycle the refrigerant is super heated

C.O.P is reduced

C.O.P is increased

Work done is reduced

Refrigerating effect is reduced

Q6 | Heat is absorbed by a refrigerant, during a refrigeration cycle in a

condenser

evaporator

compressor

throttle valve

Q7 | What is the effect of frost on the cooling coils of the evaporator of refrigeration system

It reduces the life of cooling coils

It increases the compressor pressure

It makes the compressor run for comparatively short runs

It acts as the insulator and decreases the heat transfer rate

Q8 | The widely used refrigerant in domestic refrigerators is

Carbon-dioxide

Sulphur dioxide

Freon-12

Ammonia

Q9 | Freon group refrigerants are

toxic

inflamma

nontoxic and inflammable

non- toxic & non-inflammable

Q10 | Latent heat of vaporization of a refrigerant ,at lower temperatures and pressures

increase

decreases

remains constant

unpredictable

Q11 | The refrigerant with highest critical pressure is

Carbon dioxide

Ammonia

Freon-11

Freon-22

Q12 | The Refrigerant commonly used in commercial ice plants is

Carbon-dioxide

Air

Ammonia

Freon-12

Q13 | Which of the following refrigerants has the lowest boiling point?

Freon-12

Carbon-dioxide

Ammonia

Sulphur dioxide

Q14 | In a flooded type of Evaporator which of the following types of expansion device is utilized

Float Valve

Thermostatic device

Capillary tube

Self actuated expansion valve

Q15 | Which of the following statements are TRUE?

A capillary tube is a variable opening area type expansion device

In a capillary tube pressure drop takes place due to fluid friction

In a capillary tube pressure drop takes place due to fluid acceleration

In a capillary tube pressure drop takes place due to fluid friction and acceleration

Q16 | Co-efficient of performance of vapour absorption refrigeration system as compared to that for vapour compression refrigeration system is

more

less

may be more or less

un - predictable

Q17 | The function of compressor in vapour compression refrigeration system is performed in vapour absorption system by

generator

absorber

generator, absorber and liquid pump

absorber and liquid pump

Q18 | In vapour absorption refrigeration system heating in generator is done at 100°C, refrigeration in evaporator at 10°C and cooling by cooling water in condenser at 30°C. The (COP)max is

0.5

0.35

2

in sufficient data

Q19 | Electrolux system of refrigeration has

only one liquid pump

only two liquid pumps

no liquid pump

none of the above

Q20 | Electrolux refrigerators has the following working substances

Hydrogen

Ammonia and Hydrogen

Ammonia and water

Ammonia, hydrogen and water

Q21 | Which of the following system can be called as mechanical system of refrigeration

Vapour absorption system

Vapour compression system

Steam jet refrigeration system

None of the above

Q22 | The vapour absorption refrigeration system using Ammonia – water has cycle operating pressures

higher than that using Lithium Bromide – water

lower than that using Lithium Bromide – water

may be higher or lower depending upon application

higher for sub-zero application and lower for above zero application

Q23 | Shaft work required for vapour absorption system to produce 1 ton refrigeration may be only

50 to 60% of that required for vapour compression system

20 to 30% of that required for vapour compression system

1 to 2% of that required for vapour compression system

none of the above

Q24 | Work of compression of the fluid in vapour absorption refrigeration system as compared to that for vapour compression refrigeration system is

les

more

may be more or less

un - predictable

Q25 | Munters Platen system of refrigeration is

Vapour absorption system with ammonia and water

Vapour compression system with ammonia as working substance

Electrolux system with Hydrogen, ammonia and water as working substances

none of the above