The freezing point of sulphur dioxide is
-56.6°C
-75.2°C
-77.7°C
-135.8°C
Correct Answer :
B. -75.2°C
Related Questions
Cooling water is required for following equipment in ammonia absorption plant
Condenser
Evaporator
Absorber
Condenser, absorber and separator (rectifier)
The humidification process, on the psychrometric chart is shown by
Horizontal line
Vertical line
Inclined line
Curved line
A good refrigerant should have
High latent heat of vaporisation and low freezing point
High operating pressures and low freezing point
High specific volume and high latent heat of vaporisation
Low C.O.P. and low freezing point
A refrigeration system
Removes heat from a low temperature body and delivers it to a high temperature body
Removes heat from a high temperature body and delivers it to a low temperature body
Rejects energy to a low temperature body
None of the above
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
In a domestic vapour compression refrigerator, the refrigerant commonly used is
CO₂
Ammonia
R-12
All of these
In a spray washing system, if the temperature of water is higher than the dry bulb temperature of entering air, then the air is
Heated and dehumidified
Heated and humidified
Cooled and humidified
Cooled and dehumidified
Highest pressure encountered in a refrigeration system should be
Critical pressure of refrigerant
Much below critical pressure
Much above critical pressure
Near critical pressure
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
During sensible cooling of air, specific humidity
Remains constant
Increases
Decreases
None of these
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 wet bulb temperature during sensible heating of air
Remains constant
Increases
Decreases
None of these
The alignment circle is marked on the psychrometric chart at
20°C DBT and 50% RH
26°C DBT and 50% RH
20°C DBT and 60% RH
26°C DBT and 60% RH
The refrigerant after condensation process is cooled below the saturation temperature before throttling. Such a process is called
Sub-cooling or under-cooling
Super-cooling
Normal cooling
None of these
Critical temperature is the temperature above which
A gas will never liquefy
A gas will immediately liquefy
Water will evaporate
Water will never evaporate
In a bootstrap air evaporative cooling system, the evaporator is provided
Between the combustion chamber and the first heat exchanger
Between the first heat exchanger and the secondary compressor
Between the secondary compressor and the second heat exchanger
Between the second heat exchanger and the cooling turbine
Formation of frost on evaporator in refrigerator
Results in loss of heat due to poor heat transfer
Increases heat transfer rate
Is immaterial
Can be avoided by proper design
Domestic refrigerator working on vapour compression cycle uses the following type of expansion device
Electrically operated throttling valve
Manually operated valve
Thermostatic valve
Capillary tube
The freezing point of sulphur dioxide is
-56.6°C
-75.2°C
-77.7°C
-135.8°C
The bank of tubes at the back of domestic refrigerator is
Condenser tubes
Evaporator tubes
Refrigerant cooling tubes
Capillary tubes
The thermal diffusivity for gases is generally __________ those for liquids.
Equal to
Less than
Greater than
None of these
Moisture in Freon refrigeration system causes
Ineffective refrigeration
High power consumption
Freezing automatic regulating valve
Corrosion of whole system
In mechanical refrigeration system, the refrigerant has the maximum temperature
In evaporator
Before expansion valve
Between compressor and condenser
Between condenser and evaporator
In actual air-conditioning applications for R-12 and R-22, and operating at a condenser temperature of 40° C and an evaporator temperature of 5° C, the heat rejection factor is about
1
1.25
2.15
5.12
The dry bulb temperature lines, on the psychrometric chart are
Vertical and uniformly spaced
Horizontal and uniformly spaced
Horizontal and non-uniformly spaced
Curved lines
Superheating in a refrigeration cycle
Increases C.O.P
Decreases C.O.P
C.O.P remains unaltered
Other factors decide C.O.P
The coefficient of performance (C.O.P.) of a refrigerator working as a heat pump is given by
(C.O.P.)P = (C.O.P.)R + 2
(C.O.P.)P = (C.O.P.)R + 1
(C.O.P)P = (C.O.P)R - 1
(C.O.P)P = (C.O.P)R
The superheating in a refrigeration cycle
Does not alter C.O.P.
Increases C.O.P.
Decreases C.O.P.
None of these
Pick up the wrong statement. A refrigerant should have
Tow specific heat of liquid
High boiling point
High latent heat of vaporisation
Higher critical temperature
A heat pump working on a reversed Carnot cycle has a C.O.P. of 5. It works as a refrigerator taking 1 kW of work input. The refrigerating effect will be
1 kW
2 kW
3 kW
4 kW