Which loads should the evaporator coil design primarily address?

• A. electrical and mechanical loads
• B. radiant and convective loads
• C. startup and shutdown loads
• D. latent and sensible loads

Answer: (D)

The key idea is that an evaporator coil is designed to remove both sensible and latent loads from the conditioned space. As warm room air passes over the cold coil, sensible heat is transferred to the refrigerant, dropping the air temperature. At the same time, the coil surface is cold enough to cause moisture in the air to condense on the coils, which removes latent heat and reduces humidity. So the coil must handle the total cooling effect, which is the combination of sensible cooling (temperature drop) and latent cooling (dehumidification). This is why the design focus is on latent and sensible loads. Startup or shutdown transients, and radiant or convective transfer mechanisms, aren’t the primary steady-state design loads for sizing the evaporator coil.