The pressure at the outlet of a refrigerant compressor is called
Suction pressure
Discharge pressure
Critical pressure
Back pressure
Correct Answer :
B. Discharge pressure
Related Questions
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)
In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is
Less than 2 kg
More than or equal to 3.65 kg
More than 10 kg
There is no such consideration
For large tonnage (more than 200 TR) air-conditioning applications, the compressor recommended is
Reciprocating
Rotating
Centrifugal
Screw
The coefficient of performance of Electrolux refrigerator is the ratio of
Heat supplied by the gas burner to the heat absorbed by the evaporator
Heat absorbed by the evaporator to the heat supplied by the gas burner
Heat supplied by the gas burner minus the heat absorbed by the evaporator to the heat supplied by the gas burner
Heat absorbed by the evaporator minus the heat supplied by the gas burner to the heat absorbed by the evaporator
Which of the following refrigerant has the highest freezing point.
Ammonia
Carbon dioxide
Sulphur dioxide
R-12
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
Rating of a domestic refrigerator is of the order of
0.1 ton
5 tons
10 tons
40 tons
The sub-cooling in a refrigeration cycle
Does not alter C.O.P.
Increases C.O.P.
Decreases C.O.P.
None of these
The wet bulb temperature at 100% relative humidity is ________ dry bulb temperature.
Same as
Lower than
Higher than
None of these
The power per tonne of refrigeration is
3.5/C.O.P.
C.O.P/3.5
3.5 × C.O.P.
None of these
Which of the following statement is wrong?
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.
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 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
The lowest thermal diffusivity is of
Iron
Lead
Aluminium
Rubber
The boiling point of ________ is 10.5°C.
Ammonia
R-12
Sulphur dioxide
Carbon dioxide
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 pressure at the inlet of a refrigerant compressor is called
Suction pressure
Discharge pressure
Critical pressure
Back pressure
The condition of refrigerant after passing through the expansion or throttle valve, in a vapour compression system is
High pressure saturated liquid
Wet vapour
Very wet vapour
Dry vapour
In aircraft, air refrigeration Cycle is used because of
Low weight per tonne of refrigeration
High heat transfer rate
Low temperature at high altitudes
Higher coefficient of performance
Vertical lines on pressure-enthalpy chart show constant
Pressure lines
Temperature lines
Total heat lines
Entropy lines
An important characteristic of absorption system of refrigeration is
Noisy operation
Quiet operation
Cooling below 0°C
Very little power consumption
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
Critical pressure of a liquid is the pressure
Above which liquid will remain liquid
Above which liquid becomes gas
Above which liquid becomes vapour
Above which liquid becomes solid
Hydrogen is used in Electrolux refrigeration system so as to _________ the rate of evaporation of the liquid ammonia passing through the evaporator.
Equalise
Reduce
Increase
None of these
The C.O.P. of a Carnot refrigerator in winter will be _________ as compared to C.O.P. in summer.
Same
Lower
Higher
None of these
Nusselt number (NN) is given by
NN = hl/k
NN = μ cp/k
NN = ρ V l /μ
NN = V²/t.cp
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
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
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)
Dry 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