Contact Factor of a Coil

The contact factor of a coil is defined as the efficiency for dehumidification. A 100% efficient coil will bring the moisture content of air to the saturation moisture content at the apparatus dew-point, gc. The contact factor of the coil can be defined by moisture content differences:

or by specific enthalpy differences:

The contact factor of a coil depends on the design of heat transfer surfaces, air velocity and drainage of condensate.