313A Refrigeration Cycle

Question 1

What are the four main components of a basic vapour-compression refrigeration cycle?

Accepted Answer

Compressor, condenser, expansion valve, evaporator

Answer

Compressor, boiler, turbine, condenser

Answer

Pump, heater, cooler, filter

Answer

Fan, coil, thermostat, ductwork

Question 2

In the refrigeration cycle, what state change does the refrigerant undergo in the evaporator?

Accepted Answer

Liquid to gas (evaporation/boiling)

Answer

Gas to liquid (condensation)

Answer

Solid to liquid (melting)

Answer

Gas to solid (deposition)

Question 3

What is superheat in the refrigeration cycle and why is it important?

Accepted Answer

The temperature above the boiling point of the refrigerant vapour leaving the evaporator; it ensures no liquid enters the compressor

Answer

The maximum temperature the system can reach

Answer

The temperature difference between indoor and outdoor air

Answer

The heat generated by the compressor motor

Question 4

What is subcooling in the refrigeration cycle?

Accepted Answer

The temperature of the liquid refrigerant below its condensing (saturation) temperature at condenser pressure

Answer

Cooling the evaporator below 0°C

Answer

The temperature drop across the compressor

Answer

Reducing the refrigerant charge below recommended levels

Question 5

What is the relationship between pressure and boiling point of a refrigerant?

Accepted Answer

As pressure increases, the boiling point increases; as pressure decreases, the boiling point decreases

Answer

They are unrelated

Answer

As pressure increases, the boiling point decreases

Answer

The boiling point is always constant regardless of pressure

Question 6

What is the coefficient of performance (COP) in a refrigeration system?

Accepted Answer

The ratio of cooling capacity (heat removed) to the energy input (work done by compressor)

Answer

The speed at which the compressor operates

Answer

The number of refrigeration cycles per hour

Answer

The percentage of refrigerant that evaporates