The optimum effective temperature for human comfort is
Higher in winter than in summer
Lower in winter than in summer
Same in winter and summer
Not dependent on season
Correct Answer :
B. Lower in winter than in summer
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 chemical dehumidification process,
Dew point temperature decreases
Wet bulb temperature decreases
Dry bulb temperature increases
All of these
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
Degree of saturation or percentage humidity is
The mass of water vapour present in 1 m³ of dry air
The mass of water vapour present in 1 kg of dry air
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.
The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure
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
In vapour compression cycle the condition of refrigerant is superheated vapour
After passing through the condenser
Before passing through the condenser
After passing through the expansion or throttle valve
Before entering the expansion valve
A mixture of dry air and water vapour, when the air has diffused the maximum amount of water vapour into it, is called
Dry air
Moist air
Saturated air
Specific humidity
The relative coefficient of performance is
Actual COP/theoretical COP
Theoretical COP/actual COP
Actual COP × theoretical COP
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 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
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
Accumulators should have adequate volume to store refrigerant charge at least
10 %
25 %
50 %
75 %
The thermostatic expansion valve is also called
Constant pressure valve
Constant temperature valve
Constant superheat valve
None of these
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
In a refrigeration cycle, the flow of refrigerant is controlled by
Compressor
Condenser
Evaporator
Expansion valve
The index which correlates the combined effects of air temperature, relative humidity and air velocity on the human body, is known as
Mean radiant temperature
Effective temperature
Dew point temperature
None of these
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 temperature of air recorded by a thermometer, when its bulb is surrounded by a wet cloth exposed to the air, is called
Wet bulb temperature
Dry bulb temperature
Dew point temperature
None of these
The pressure at the inlet of a refrigerant compressor is called
Suction pressure
Discharge pressure
Critical pressure
Back pressure
The wet bulb temperature at 100% relative humidity is ________ dew point temperature.
Same as
Lower than
Higher than
None of these
Most of the domestic refrigerators work on the following refrigeration system
Vapour compression
Vapour absorption
Carnot cycle
Electrolux refrigerator
Highest temperature encountered in refrigeration cycle should be
Near critical temperature of refrigerant
Above critical temperature
At critical Temperature
Much below critical temperature
The atmospheric air at dry bulb temperature of 15°C enters a heating coil maintained at 40°C. The air leaves the heating coil at 25°C. The bypass factor of the heating coil is
0.376
0.4
0.6
0.67
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
Aqua ammonia is used as refrigerant in the following type of refrigeration system
Compression
Direct
Indirect
Absorption
The humidity ratio or specific humidity is the mass of water vapour present in
1 m3 of wet air
1 m3 of dry air
1 kg of wet air
1 kg of dry air
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 boiling point of ammonia is
-10.5°C
-30°C
-33.3°C
-77.7°C
One ton of the refrigeration is
The standard unit used in refrigeration problems
The cooling effect produced by melting 1 ton of ice
The refrigeration effect to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours
The refrigeration effect to produce 1 ton of ice at NTP conditions
The ratio of heat extracted in the refrigerator to the work-done on the refrigerant is called
Coefficient of performance of refrigeration
Coefficient of performance of heat pump
Relative coefficient of performance
Refrigerating efficiency