Abstract: A dehumidifier for air is provided. The dehumidifier includes a housing with an inlet for process air, an outlet for process air, and an opening for regeneration air. The dehumidifier includes a dehumidification element, a fan for bringing process air to flow through at least a first portion of the dehumidification element, and a heating element to heat a part of process air flowing through the dehumidification element for regeneration of the dehumidification element by using the heated process air. A controller controls the amount of air that flows though the outlet for process air and the opening for regeneration air and the sensor/meter to calculate consumed power for the heating element, wherein the heating element is a PTC heater. The controller allows a user in a simple way to adjust the operating parameters to a desired operating mode.

Abstract: A method and apparatus for increasing the yield of an air-drying process with the aid of a dehumidifier 2 and a condenser/heat-exchanger 3 involves delivering wet regenerating air exiting the dehumidifier to one side of the condenser/heat-exchanger so as to deliver energy to the process air entering the other side. Condensation deriving from the regenerating air is collected and carried away, and the heated, dried process air 21 is delivered to the dehumidifier in which moisture is extracted from the air and the air further dried. The departing wet regenerating air may, after its delivery process, be led to the room, atmosphere or the flow of process air.