313D Fundamentals of Air Conditioning Systems

Question 1

What is the primary function of an evaporator coil in an air conditioning system?

Accepted Answer

Absorb heat from indoor air

Answer

The evaporator coil is a crucial component located inside the home's air handler. As warm indoor air passes over its cold surface, the liquid refrigerant inside absorbs heat and vaporizes. This process effectively removes heat and humidity from the indoor environment, cooling the air before it is recirculated.

Question 2

Which component of the system compresses refrigerant to increase its pressure and temperature?

Accepted Answer

Compressor

Answer

The compressor is often considered the 'heart' of the air conditioning system. Its primary function is to draw in low-pressure, low-temperature refrigerant vapor from the evaporator and compress it. This compression significantly increases the refrigerant's pressure and temperature, preparing it to release heat in the condenser coil.

Question 3

What occurs to the refrigerant in the condenser coil during the refrigeration cycle?

Accepted Answer

It releases heat and condenses into a liquid

Answer

In the condenser coil, the high-pressure, high-temperature refrigerant vapor releases the heat it absorbed from the indoor air to the cooler outdoor air. As it loses heat, the refrigerant undergoes a phase change, condensing back into a high-pressure liquid. This process is essential for the continuous cycle of heat transfer.

Question 4

Which principle explains the heat absorption in the evaporator coil?

Accepted Answer

Latent heat transfer during phase change

Answer

The evaporator coil cools the air primarily through latent heat transfer. As the liquid refrigerant inside the coil absorbs heat from the indoor air, it changes phase from a liquid to a gas (vaporizes) without a significant change in its own temperature. This phase change efficiently removes a large amount of heat from the surrounding air.

Question 5

What is the primary role of the expansion valve in an air conditioning system?

Accepted Answer

Reduce refrigerant pressure and temperature

Answer

The expansion valve, also known as a metering device, is positioned between the condenser and the evaporator. Its critical role is to precisely control the flow of liquid refrigerant into the evaporator and, more importantly, to reduce its pressure and temperature. This pressure drop causes the refrigerant to flash into a cold, low-pressure mixture of liquid and vapor, ready to absorb heat.

(313D) Residential Air Conditioning Systems Mechanic Certification Practice Test

(313D) Residential Air Conditioning Systems Mechanic Certification Practice Test

313D Fundamentals of Air Conditioning Systems