The temperature of ammonia after compression in a vapour compression system is
20 to 50°C
50 to 70°C
70 to 110°C
None of these
Correct Answer :
C. 70 to 110°C
Related Questions
Air refrigeration cycle is used in
Commercial refrigerators
Domestic refrigerators
Air-conditioning
Gas liquefaction
During a refrigeration cycle, heat is rejected by the refrigerant in a
Compressor
Condenser
Evaporator
Expansion valve
Moisture should be removed from refrigerants to avoid
Freezing at the expansion valve
Restriction to refrigerant flow
Corrosion of steel plates
All of these
The superheated vapour region, in a pressure enthalpy chart, is represented by the space
To the left of saturated liquid line
To the right of saturated liquid line
Between the saturated liquid line and saturated vapour line
None of the above
In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to
Collect liquid refrigerant and prevent it from going to compressor
Detect liquid in vapour
Superheat the vapour
Collect vapours
The bypass factor for a cooling coil
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
During heating and humidification, the final relative humidity of air
Can be lower or higher than that of the entering air
Is lower than that of the entering air
Is higher than that of the entering air
None of the above
The pressure at the outlet of a refrigerant compressor is called
Suction pressure
Discharge pressure
Critical pressure
Back pressure
The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P.
More
Less
Equally
Unpredictable
On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process
Involves no change in volume
Takes place at constant temperature
Takes place at constant entropy
Takes place at constant pressure
The difference between dry bulb temperature and wet bulb temperature, is called
Dry bulb depression
Wet bulb depression
Dew point depression
Degree of saturation
In air-conditioning of aeroplanes, using air as a refrigerant, the cycle used is
Reversed Carnot cycle
Reversed Joule cycle
Reversed Brayton cycle
Reversed Otto cycle
Cooling water is required for following equipment in ammonia absorption plant
Condenser
Evaporator
Absorber
Condenser, absorber and separator (rectifier)
The thermostatic expansion valve operates on the changes in the
Degree of superheat at exit from the evaporator
Temperature of the evaporator
Pressure in the evaporator
None of the above
A Bell Coleman refrigerator working on dense air system as compared to open air system, for the same range of temperature, results in ________ power per tonne of refrigeration.
Same
Lower
Higher
None of these
The evaporator changes the low pressure liquid refrigerant from the expansion valve into
High pressure liquid refrigerant
Low pressure liquid and vapour refrigerant
Low pressure vapour refrigerant
None of these
The wet bulb depression is zero when relative humidity is
Zero
0.5
0.75
1.0
A refrigerant with the highest critical pressure is
R-11
R-12
R-22
Ammonia
The horizontal and non-uniformly spaced lines on a psychrometric chart indicates
Dry bulb temperature
Wet bulb temperature
Dew point temperature
Specific humidity
The humidification process, on the psychrometric chart is shown by
Horizontal line
Vertical line
Inclined line
Curved line
The central air conditioning system has ________ overall efficiency as compared to individual systems.
Same
Lower
Higher
None of these
The capillary tube, as an expansion device, is used in
Domestic refrigerators
Water coolers
Room air conditioners
All of these
The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure, is called
Humidity ratio
Relative humidity
Absolute humidity
Degree of saturation
The wet bulb temperature during sensible heating of air
Remains constant
Increases
Decreases
None of these
Freon group of refrigerants are
Inflammable
Toxic
Non-inflammable and toxic
Nontoxic and non-inflammable
For ammonia refrigerating systems, the tubes of a shell and tube condenser are made of
Copper
Aluminium
Steel
Brass
The undesirable property of a refrigerant is
Non-toxic
Non-flammable
Non-explosive
High boiling point
A refrigerating system operating on reversed Brayton refrigeration cycle is used for maintaining 250 K. If the temperature at the end of constant pressure cooling is 300K and rise in the temperature of air in the refrigerator is 50 K, then the net work of compression will be (assume air as working substance with Cp = 1 kJ/kg)
25 kJ/kg
50 kJ/kg
100 kJ/kg
125 kJ/kg
The moisture in a refrigerant is removed by
Evaporator
Safety relief valve
Dehumidifier
Driers
The operating temperature of a cold storage is 2°C. The heat leakage from the surrounding is 30 kW for the ambient temperature of 40°C. The actual C.O.P. of refrigeration plant used is one fourth that of ideal plant working between the same temperatures. The power required to drive the plant is
1.86 kW
3.72 kW
7.44 kW
18.6 kW