What type of heat exchanger does cooling/heating fluid REMAIN in gaseous or liquid phase?

• A. Single Phase
• B. Two-Phase
• C. Condensing
• D. Evaporating

Answer: (A)

Single-phase heat transfer means the working fluid stays in one phase (either all liquid or all gas) as it moves through the exchanger. Since no phase change occurs, there’s no latent heat involved—the heat transfer is sensible, driven by the fluid’s specific heat and temperature change. The fluid remains gaseous or liquid along the entire length, which is why this fits the single-phase category. In contrast, condensing and evaporating involve phase change (vapor to liquid or liquid to vapor), and two-phase flow means both liquid and vapor are present simultaneously.