Refrigeration and Air-conditioning: Assignment 4:

                                    

1. A good refrigerant should have

very high normal boiling point

low latent heat of vaporization

high sensible heat capacity

high latent heat of vaporization

Ans: d

 

2. The main characteristic feature of air refrigeration system is that throughout the cycle the refrigerant remains in 

Gaseous state

Liquid state

Gaseous and liquid state

Super-cooled state

Ans: c

 

3. A vapour-absorption system works with temperature of generator (T_g)= 95^oC, absorber temperature (T_a) = 35^oC and evaporator temperature (T_e) = -10^oC. COP of the system is

0.65

0.75

0.85

0.95

Ans: d

 

4. If the temperature of evaporator is reduced to -20 ^oC find new temperature of generator in ^oC to avoid any change in the COP of the system

105

110

115

120

Ans: c

 

5. Refrigerants having a lower flammability limit of more than 0.10 kg/m3 @21°C and 101 kPa belongs to

class 1

class 2

class 3

class 4

Ans: b

 

6. R-600a is also known as 

isobutane

air

ammonia

oxygen

Ans: a

 

7. In absorption refrigeration system there is not any

evaporator

condenser

compressor

all of the above

Ans: c

 

8. In water-LiBr absorption system the temperature of boiler should not exceed 120°C to avoid 

corrosion

decomposition of LiBr

overheating of system

all of the above

Ans: d

9. The COP of a vapor compression plant in comparison to vapor absorption plant is

More

Less

Same

More/less depending on size of plant

Ans: a

 

10. In aqua-ammonia and Lithium-bromide water absorption refrigeration systems, the refrigerants are respectively

Ammonia and water

Ammonia and Li-Br

Water and water

Water and Li-Br               

Ans: a