Differentiating evaporator and condenser coils, where heat transfer occurs and what state changes take place?

• A. Evaporator coil absorbs heat and boils liquid refrigerant to vapor; condenser coil rejects heat and condenses vapor to liquid.
• B. Evaporator coil rejects heat and condenses vapor; condenser coil absorbs heat and boils liquid to vapor.
• C. Evaporator coil cools the refrigerant in high pressure; condenser warms it in low pressure.
• D. Evaporator and condenser both only condense refrigerant; no boiling occurs.

Answer: (A)

The core idea is that these two coils handle heat transfer and phase changes in opposite ways within the refrigeration cycle. In the evaporator, the refrigerant is at low pressure and low temperature; it absorbs heat from the space being cooled and boils, changing from liquid to vapor. This phase change requires latent heat, which is drawn from the surroundings and causes the cooling effect. In the condenser, the refrigerant arrives as a hot, high-pressure vapor and rejects heat to the surroundings, causing the vapor to condense back into a liquid. This releases latent heat to the surroundings and closes the cycle. The cooler space gets heat removed via evaporation, while the condenser serves to remove heat from the system by turning vapor back into liquid. If the roles were reversed, or if the evaporator were to reject heat or the condenser to absorb heat, the cooling process wouldn’t work as designed. The evaporator operates at low pressure and temperature, while the condenser operates at high pressure and temperature, reflecting their distinct roles in the cycle.