The humid air is sucked into the machine by the fan, and the evaporator surface is lowered below the dew point temperature of the air through the compressor refrigeration system. At this time, when the humid air passes through the evaporator, the water in the air will decompose and adhere to the evaporator surface (note: just like the principle of taking out a bottle of water from the refrigerator in summer, there will be a layer of condensed water on the outside of the bottle). The water will flow along the hydrophilic foil on the evaporator to the water tray and then flow to the water tank or drainage pipe for discharge. The dehumidified dry cold air is heated by the condenser and discharged outside the machine, so the circulation reduces the temperature inside and outside.