Evaporators and Condensers, Objective 3

What occurs when an evaporator operates below the dew point and below the freezing point of the evaporator air entering temperature?

• Moisture is precipitated out of the air.

• The refrigeration cycle starts.

• The compressor shuts down.

• The evaporator fan stops.

Which defrost method is the most economical and does not require additional components like timers or solenoids?

• Off-cycle defrost

• Electric defrost

• Manual defrost

• Hot-gas defrost

What is the primary fault that causes excessive run time in off-cycle defrost systems?

• Low refrigerated space heat load

• High ambient humidity

• Fouled condenser

• Short-cycled condenser air flow

Which defrost method uses resistance heaters embedded in the evaporator fins?

• Manual defrost

• Hot-gas defrost

• Electric defrost

• Reverse cycle defrost

What does the hot-gas defrost method use to defrost the evaporator?

• Superheated refrigerant vapour

• Warm air

• Brine spray

• Water spray

What does the evaporator fan do during the defrost cycle in a hot-gas defrost system?

• Reverses direction

• Runs at a lower speed

• Shuts off

• Runs at maximum speed

What is the purpose of a re-evaporator coil in a hot-gas defrost system?

• To increase the pressure

• To cool down the evaporator

• To heat the refrigerant

• To evaporate condensed liquid

Which defrost method uses a 4-way reversing valve to reverse the refrigerant flow?

• Spray defrost

• Reverse cycle defrost

• Electric defrost

• Off-cycle defrost

What is used to defrost an evaporator coil in the spray defrost method?

• Hot air

• Water

• Brine

• Antifreeze solution

What factors can affect the number of defrosts and the duration of each defrost cycle for a specific installation?

• Business conditions and refrigerated space frequency of use

• Product types and turnover

• Seasons and weather conditions

• All of the above