In the evaporator, latent heat transfer occurs as the refrigerant boils and absorbs heat

• A. It involves only sensible heat
• B. It involves only latent heat
• C. It involves latent heat transfer as the refrigerant boils and absorbs heat
• D. It does not involve phase change

Answer: (C)

In an evaporator, the key energy move is the latent heat of vaporization. As the refrigerant absorbs heat from the space being cooled, it reaches its boiling point and changes from a liquid to a vapor. That energy goes into breaking intermolecular bonds and changing the phase, not into raising the refrigerant’s temperature. So the transfer is latent heat associated with boiling, which is exactly what this description states. It wouldn’t be correct to say only sensible heat, since there’s a phase change involved; it wouldn’t be correct to say there’s no phase change, since boiling is a phase change; and while “only latent heat” captures the main idea, describing it as latent heat transfer during boiling and heat absorption most clearly conveys what happens.