HVAC Refrigeration Fundamentals

Question 1

What is the primary purpose of the refrigerant in an HVAC system?

Accepted Answer

To transfer heat from inside to outside

Answer

Refrigerant absorbs heat indoors at the evaporator and releases it outdoors at the condenser, transferring heat out of the conditioned space.

Question 2

In the refrigeration cycle, where does the refrigerant change from a low-pressure gas to a high-pressure gas?

Accepted Answer

Compressor

Answer

The compressor takes low-pressure refrigerant vapor and compresses it into a high-temperature, high-pressure gas.

Question 3

What is superheat in an HVAC system?

Accepted Answer

Refrigerant temperature above its boiling point at a given pressure

Answer

Superheat is the number of degrees the refrigerant vapor is heated above its saturation (boiling) temperature at a given pressure.

Question 4

What does subcooling refer to in a refrigeration system?

Accepted Answer

Liquid refrigerant cooled below its condensing temperature

Answer

Subcooling is the number of degrees the liquid refrigerant has been cooled below its saturation temperature at condenser pressure.

Question 5

Which component in the refrigeration cycle causes the refrigerant to drop in pressure and temperature?

Accepted Answer

Metering device (expansion valve)

Answer

The metering device (TXV or fixed orifice) restricts refrigerant flow, causing a pressure drop that lowers the refrigerant's temperature.

HVAC - Heating, Ventilation, and Air Conditioning Practice Test