WorksheetsRAC M3 Assessment Revision
Total questions: 18
Worksheet time: 12mins
Which component in a refrigeration system compresses low-pressure vapor into high-pressure vapor?
Evaporator
Compressor
Condenser
Receiver
What is the main function of the condenser in a refrigeration system?
To absorb heat from the surroundings
To increase the refrigerant pressure
To reject heat to the surroundings and condense vapor into liquid
To regulate refrigerant flow
Which device controls the refrigerant flow to maintain a constant pressure in the evaporator?
Thermostatic Expansion Valve
Capillary Tube
Pressure Switch
Solenoid Valve
Which of the following is considered a better insulator for refrigeration applications?
Fibre-glass batts
Expanded polystyrene (EPS)
Polyurethane foam
Armaflex foam
What does the term 'latent heat of fusion' refer to?
Heat absorbed by solid to melt into liquid without temperature change
Heat released when vapor condenses
Heat added to raise temperature of a liquid
Heat lost during evaporation
The ratio of the actual amount of moisture in the air to the maximum amount it can hold at a given temperature is called ___________.
relative humidity
dew point
absolute humidity
specific heat
The temperature of a vapor above its saturation temperature at a given pressure is referred to as ___________.
superheated temperature (or superheat)
latent heat
sensible heat
critical temperature
The total heat content of a system, which represents the sum of internal energy and the product of pressure and volume, is known as ___________.
enthalpy
entropy
specific heat
internal energy
The efficiency of a refrigeration system is expressed as the ___________, which is the ratio of the refrigerating effect produced to the work input.
coefficient of performance (COP)
thermal conductivity
specific heat capacity
latent heat
A graphical tool used to analyse the thermodynamic properties of moist air in air-conditioning applications is called the ___________.
psychrometric chart
Mollier diagram
P-h diagram
T-s diagram
Air conditioning systems achieve human comfort through control of which air properties?
Temperature, humidity, and air quality
Only temperature
Only humidity
Only air pressure
Which of the following lists the four main components of a basic vapor-compression refrigeration system and their functions?
Compressor, condenser, expansion valve, evaporator: compresses refrigerant, condenses heat, expands refrigerant, absorbs heat
Pump, heater, filter, fan: circulates fluid, heats air, removes impurities, moves air
Compressor, radiator, thermostat, humidifier: compresses air, cools air, controls temperature, adds moisture
Evaporator, generator, absorber, rectifier: absorbs heat, generates power, absorbs refrigerant, purifies refrigerant
The process of heat transfer in a refrigeration system involves:
removing heat from a low-temperature area and releasing it to a high-temperature area
adding heat to a low-temperature area and removing it from a high-temperature area
transferring heat only within the refrigerant without any external exchange
preventing any heat movement between different areas
The effect of humidity on comfort cooling and refrigerated food is:
High humidity reduces comfort and can spoil refrigerated food faster.
High humidity increases comfort and preserves refrigerated food longer.
Low humidity has no effect on comfort or refrigerated food.
Humidity only affects comfort, not refrigerated food.
15. The difference between hermetic and semi-hermetic compressors is:
Hermetic compressors are completely sealed, while semi-hermetic compressors can be opened for maintenance.
Hermetic compressors can be opened for maintenance, while semi-hermetic compressors are completely sealed.
Both hermetic and semi-hermetic compressors are always open to the atmosphere.
Semi-hermetic compressors are used only for air conditioning, while hermetic compressors are used only for refrigeration.
Define Coefficient of Performance (COP).
Coefficient of Performance (COP) is a ratio of useful heating or cooling provided to work required. It is used to measure the efficiency of heating and cooling systems.
Coefficient of Performance (COP) is the ratio of input energy to output energy in any mechanical system.
Coefficient of Performance (COP) is a measure of the speed at which a system operates.
Coefficient of Performance (COP) is the difference between the highest and lowest temperatures in a system.
Define Compression (Pressure) Ratio.
Compression (Pressure) Ratio is the ratio of the absolute discharge pressure to the absolute suction pressure in a compressor.
Compression (Pressure) Ratio is the ratio of the compressor speed to the motor speed.
Compression (Pressure) Ratio is the ratio of the inlet temperature to the outlet temperature in a compressor.
Compression (Pressure) Ratio is the ratio of the compressor volume to the cylinder volume.
Find
1. Refrigeration Effect (We), [kJ/kg]
2. Thermal Equivalent of Compressor Work (Aw), [kJ/kg]
3. Condensing Load (Wc), (kJ/kg]
4. Coefficient of Performance (COP)
5. Compression (Pressure) Ratio
