Which of the following lists the three primary methods of heat transfer?

• A. Radiation, Evaporation, and Conduction
• B. Boiling, Freezing, and Condensation
• C. Conduction, Convection, and Radiation
• D. Subcooling, Superheating, and Saturation

Answer: (C)

Heat moves in three primary ways: conduction, convection, and radiation. Conduction transfers energy through direct contact or via shared molecular vibrations, like heat moving through metal walls of pipes and equipment. Convection involves the movement of heat by a moving fluid, such as refrigerant or cooling water circulating and carrying energy with it. Radiation transfers heat through electromagnetic waves, allowing heat to be exchanged between surfaces without direct contact or fluid flow.

The other options mix in phase-change processes or refrigerant state terms. Evaporation, boiling, and condensation are phase changes that involve latent heat, not one of the fundamental modes of heat transfer. Subcooling, superheating, and saturation describe the refrigerant’s condition or quality, not the mechanism by which heat is transferred.