🔍 Key Concepts

• Direct expansion (DX) evaporator operation in a basic refrigeration cycle • Difference between refrigerant side (inside the tube) and medium being cooled (outside the tube) in a dry-type evaporator • Meaning of “dry-type” versus flooded evaporator design

💭 Think About

• In a dry-type direct expansion evaporator, where does the refrigerant actually flow: inside the tubes or outside the tubes? • What substance (air, water, or refrigerant) normally comes into contact with the outside surfaces of the evaporator coils in an HVAC or refrigeration unit? • Why would adding insulation directly on the heat-transfer surface (inside or outside the coil) be a problem for evaporator performance?

✅ Before You Answer

• Verify which side of the coil carries refrigerant and which side carries the medium being cooled (air, water, etc.). • Check whether an evaporator coil’s outer surface is normally insulated or exposed to allow heat transfer. • Confirm what the term “dry-type” implies about how much refrigerant is present in the evaporator and where it is located.