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
Correct Answer :
A. Degree of superheat at exit from the evaporator
Related Questions
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
If a gas is to be liquefied, its temperature must be
Increased to a value above its critical temperature
Reduced to a value below its critical temperature
Equal to critical temperature
None of the above
The relative humidity lines on a psychrometric chart are
Vertical and uniformly spaced
Horizontal and uniformly spaced
Horizontal and non-uniformly spaced
Curved lines
The process of under-cooling is generally brought about by
Circulating more quantity of cooling water through the condenser
Using water colder than the main circulating water
Employing a heat exchanger
Any one of the above
In a vapour absorption refrigeration system, the compressor of the vapour compression system is replaced by
Liquid pump
Generator
Absorber and generator
Absorber, generator and liquid pump
Nusselt number (NN) is given by
NN = hl/k
NN = μ cp/k
NN = ρ V l /μ
NN = V²/t.cp
During sensible cooling of air, specific humidity
Remains constant
Increases
Decreases
None 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
The dehumidification process, on the psychrometric chart, is shown by
Horizontal line
Vertical line
Inclined line
Curved line
Highest temperature encountered in refrigeration cycle should be
Near critical temperature of refrigerant
Above critical temperature
At critical Temperature
Much below critical temperature
Ammonia is
Non-toxic
Non-inflammable
Toxic and non-inflammable
Highly toxic and inflammable
While designing the refrigeration system of an aircraft, the prime consideration is that the
System has high C.O.P.
Power per TR is low
Mass of refrigerant circulated in the system is low
Mass of the refrigeration equipment is low
The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases,
Will be higher
Will be lower
Will remain unaffected
May be higher or lower depending upon the nature of noncondensable gases
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 supplied to a compressor must be
Superheated vapour refrigerant
Dry saturated liquid refrigerant
A mixture of liquid and vapour refrigerant
None of these
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
In a pressure enthalpy chart, the space to the left of the saturated liquid line represents
Wet vapour region
Superheated vapour region
Sub-cooled liquid region
None of these
The wet bulb temperature during sensible cooling of air
Remains constant
Increases
Decreases
None of these
A pressure gauge on the discharge side of a refrigerant compressor reads too high. The reasons will be
Lack of cooling water
Water temperature being high
Dirty condenser surface
All of these
The material of pipe lines for a system using Freon as a refrigerant should be
Brass
Copper
Steel
Aluminium
In a domestic vapour compression refrigerator, the refrigerant commonly used is
CO₂
Ammonia
R-12
All of these
The central air conditioning system has ________ overall efficiency as compared to individual systems.
Same
Lower
Higher
None of these
The bypass factor (B. P. F.) in case of sensible heating of air is (Where td₁ = Dry bulb temperature of air entering the heating coil, td₂ = Dry bulb temperature of air leaving the heating coil, and td₃ = Dry bulb temperature of heating coil)
(td₂ - td₃)/(td₃ - td₁)
(td₃ - td₂)/(td₃ - td₁)
(td₃ - td₁)/(td₂ - td₃)
(td₃ - td₁)/(td₃ - td₂)
Wet bulb temperature is the temperature of air recorded by a thermometer, when
It is not affected by the moisture present in the air
Its bulb is surrounded by a wet cloth exposed to the air
The moisture present in it begins to condense
None of the above
Air refrigeration cycle is used in
Domestic refrigerators
Commercial refrigerators
Air conditioning
Gas liquefaction
The coefficient of performance of Heat Pump is always __________ one.
Equal to
Less than
Greater than
None of these
Condensing temperature in a refrigerator is the temperature
Of cooling medium
Of freezing zone
Of evaporator
At which refrigerant gas becomes liquid
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
The centrifugal compressors are generally used for refrigerants that require
Small displacements and low condensing pressures
Large displacements and high condensing pressures
Small displacements and high condensing pressures
Large displacements and low condensing pressures
Which of the following refrigerants has lowest freezing point?
Freon-12
NH3
CO2
Freon-22