Compression
Expansion
Condensation
Evaporation
D. Evaporation
Near critical temperature of refrigerant
Above critical temperature
At critical Temperature
Much below critical temperature
Increases with increase in velocity of air passing through it
Decreases with increase in velocity of air passing through it
Remains unchanged with increase in velocity of air passing through it
May increase or decrease with increase in velocity of air passing through it depending upon the condition of air entering
Same
More
Less
More or less depending on ambient conditions
20°C DBT and 50% RH
26°C DBT and 50% RH
20°C DBT and 60% RH
26°C DBT and 60% RH
High, of the order of 25°
As low as possible (3 to 11°C)
Zero
Any value
(td₁ -td₃)/( td₂ -td₃)
(td₂ -td₃)/( td₁ -td₃)
(td₃ -td₁)/( td₂ -td₃)
(td₃ -td₂)/( td₁ -td₃)
Before compressor
Between compressor and condenser
Between condenser and evaporator
Between condenser and expansion valve
Pressure lines
Temperature lines
Total heat lines
Entropy lines
Remains constant
Increases
Decreases
None of these
Cooling
Heating
Dehumidifying
All of these
0.3
0.6
0.67
1.5
High risibility with oil
Low boiling point
Good electrical conductor
Large latent heat
Horizontal line
Vertical line
Inclined line
Curved line
More
Less
Equally
Unpredictable
Centrifugal
Axial
Miniature sealed unit
Piston type reciprocating
Small
High
Equal
Anything
(td₂ - td₃)/(td₃ - td₁)
(td₃ - td₂)/(td₃ - td₁)
(td₃ - td₁)/(td₂ - td₃)
(td₃ - td₁)/(td₃ - td₂)
2 bar
8 bar
15 bar
30 bar
CO₂
Ammonia
R-12
All of these
Reversed Carnot cycle
Bell Coleman cycle
Both (A) and (B)
None of these
Positive
Negative
Zero
None of these
100°C
50°C
33.3°C
0°C
High pressure liquid refrigerant
Low pressure liquid and vapour refrigerant
Low pressure vapour refrigerant
None of these
Increases C.O.P
Decreases C.O.P
C.O.P remains unaltered
Other factors decide C.O.P
Simple air cooling system
Bootstrap air cooling system
Reduced ambient air cooling system
Regenerative air cooling system
Condenser
Evaporator
Compressor
Expansion valve
The performance of the vapour compression refrigerator varies considerably with both vaporising and condensing temperatures.
In vapour compression cycle, the useful part of the heat transfer is at the condenser.
In ammonia-hydrogen (Electrolux) refrigerator, no compressor, pump or fan is required.
The effect of under-cooling the liquid refrigerant is to decrease the coefficient of performance.
Ammonia
Carbon dioxide
Sulphur dioxide
R-12
A refrigerant should have low latent heat
If operating temperature of system is low, then refrigerant with low boiling point should be used
Pre-cooling and sub-cooling bf refrigerant are same
Superheat and sensible heat of a refrigerant are same
NN = hl/k
NN = μ cp/k
NN = ρ V l /μ
NN = V²/t.cp