The boiling point of ammonia is
-10.5°C
-30°C
-33.3°C
-77.7°C
Correct Answer :
C. -33.3°C
Related Questions
The relative coefficient of performance is equal to
(Theoretical C.O.P.)/ (Actual C.O.P.)
(Actual C.O.P.) /(Theoretical C.O.P.)
(Actual C.O.P.) × (Theoretical C.O.P.)
None of these
During sensible cooling of air, specific humidity
Remains constant
Increases
Decreases
None 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
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
The desirable property of a refrigerant is
Low boiling point
High critical temperature
High latent heat of vaporisation
All of these
In a reversed Brayton cycle, the heat is absorbed by the air during
Isentropic compression process
Constant pressure cooling process
Isentropic expansion process
Constant pressure expansion process
The C.O.P. of a refrigerator working on a reversed Carnot cycle is (where T₁ = Lowest absolute temperature, and T₂ = Highest absolute temperature)
T₁ / (T₂ - T₁)
(T₂ - T₁)/T₁
(T₁ - T₂)/T₁
T₂/ (T₂ - T₁)
The refrigerant used for absorption refrigerators working on heat from solar collectors is a mixture of water and
Carbon dioxide
Sulphur dioxide
Lithium bromide
R-12
The advantage of dry compression is that
It permits higher speeds to be used
It permits complete evaporation in the evaporator
It results in high volumetric and mechanical efficiency
All of the above
During humidification process, __________ increases.
Wet bulb temperature
Relative humidity
Dry bulb temperature
Specific humidity
Moisture in Freon refrigeration system causes
Ineffective refrigeration
High power consumption
Freezing automatic regulating valve
Corrosion of whole system
The vertical and uniformly spaced lines on a psychrometric chart indicates
Dry bulb temperature
Wet bulb temperature
Dew point temperature
Specific humidity
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
Presence of moisture in a refrigerant affects the working of
Compressor
Condenser
Evaporator
Expansion valve
In order to collect liquid refrigerant and to prevent it from going to a ________, a device known as accumulator is used at the suction of compressor.
Compressor
Condenser
Expansion valve
Evaporator
One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice
In 1 hour
In 1 minute
In 24 hours
In 12 hours
In a psychrometric chart, specific humidity (moisture content) lines are
Vertical and uniformly spaced
Horizontal and uniformly spaced
Horizontal and non-uniformly spaced
Curved lines
The evaporator used in household refrigerators is
Frosting evaporator
Non-frosting evaporator
Defrosting evaporator
None of these
Which of the following statement is correct for ammonia as a refrigerant?
It is toxic to mucous membranes.
It requires large displacement per TR compared to fluoro carbons.
It reacts with copper and its alloys.
All of these
Which of the following statement is correct?
The human body can lose heat even if its temperature is less than the atmospheric temperature.
The increase in air movement increases the evaporation from the human body.
The warm air increases the rate of radiation of heat from the human body.
Both (A) and (B)
The thermostatic expansion valve is also called
Constant pressure valve
Constant temperature valve
Constant superheat valve
None of these
The heat rejection factor (HRF) is given by
1 + C.O.P
1 - C.O.P.
1 + (1/C.O.P)
1 - (1/C.O.P)
If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. of compressor required will be
Same
More
Less
More/less depending on rating
The specific humidity during cooling and dehumidification
Remains constant
Increases
Decreases
None of these
Allowable pressure on high pressure side or ammonia absorption system is of the order of
Atmospheric pressure
Slightly above atmospheric pressure
24 bars
56 bars
The specific humidity during humidification process
Remains constant
Increases
Decreases
None of these
Absorption system normally uses the following refrigerant
Freon-11
Freon-22
CO2
Ammonia
The pressure at the outlet of a refrigerant compressor is called
Suction pressure
Discharge pressure
Critical pressure
Back pressure
The value of C.O.P in vapour compression cycle is usually
Always less than unity
Always more than unity
Equal to unity
Any one of the above
The domestic refrigerator uses following type of compressor
Centrifugal
Axial
Miniature sealed unit
Piston type reciprocating