Humidity control unit and method having bypass for process air

An air conditioning and dehumidification system comprising:

• an enclosed housing having a dividing wall dividing the housing into first and second air plenums;
• a refrigeration circuit including an evaporator coil in the first plenum, a condenser coil in the second plenum, and a condenser fan for drawing ambient air into the second plenum and through the condenser and discharging the air downstream from the condenser and to the outside of the housing;
• a dehumidification system in the housing including a desiccant wheel rotatably mounted in the housing to rotate in a plane perpendicular to the dividing wall whereby one segment of the wheel functioning as the process segment is located in the first plenum and a second segment of the wheel functioning as the regeneration segment is located in the second plenum;
• an ambient air supply air fan for drawing ambient air into the first plenum through the evaporator and then through the process segment of the desiccant wheel whereby the ambient air in the first plenum is cooled and dehumidified and supplied from the first plenum to an enclosure;
• an ambient air bypass defining a third plenum and means for supplying ambient air through the third plenum and selectively to the enclosure as a bypass airstream;
• and
• means for selectively cooling the bypass airstream in the third plenum,
• wherein the means for selectively cooling the bypass airstream is a chilled water coil.