Air dehumidification unit and process

Abstract

An air dehumidification unit of a heating, ventilating, and air conditioning system includes an air flow channel configured to guide a flow of air through an evaporator disposed therein, and a drainage channel coupled to the air flow channel. The drainage channel has an internal volume configured to receive a fluid condensed at the evaporator from the flow of air. The air dehumidification unit further includes a heating device configured to heat the internal volume of the drainage channel from outside of the internal volume of the drainage channel to militate against a formation of ice therein. The invention also relates to a method for dehumidifying the air in the heating, ventilating, and air conditioning system of a motor vehicle using the air dehumidification unit.

What is claimed is: 
     
         1 . An air dehumidification unit of a heating, ventilating, and air conditioning system, comprising:
 an air flow channel configured to guide a flow of air through an evaporator disposed therein;   a drainage channel coupled to the air flow channel, the drainage channel having an internal volume configured to receive a fluid condensed at the evaporator from the flow of air; and   a heating device configured to heat the internal volume of the drainage channel from outside of the internal volume of the drainage channel.   
     
     
         2 . The air dehumidification unit of  claim 1 , wherein the drainage channel is substantially vertically oriented. 
     
     
         3 . The air dehumidification unit of  claim 1 , wherein the drainage channel is formed to extend laterally outwardly from a bottom portion of the air flow channel. 
     
     
         4 . The air dehumidification unit of  claim 1 , wherein the drainage channel is formed downstream of the evaporator in the air flow channel. 
     
     
         5 . The air dehumidification unit of  claim 1 , further comprising a guiding element extending from an upstream edge in respect of the flow of air of the evaporator to an inlet of the drainage channel. 
     
     
         6 . The air dehumidification unit of  claim 5 , wherein the guiding element forms an inclined plane which facilitates a flow of the fluid into the inlet of the drainage channel. 
     
     
         7 . The air dehumidification unit of  claim 1 , wherein the heating device is integrated into a wall which defines the internal volume of the drainage channel. 
     
     
         8 . The air dehumidification unit of  claim 1 , wherein the heating device is disposed adjacent the drainage channel. 
     
     
         9 . The air dehumidification unit of  claim 1 , wherein the heating device is an electrical heating wire with a positive temperature coefficient. 
     
     
         10 . The air dehumidification unit of  claim 1 , wherein the heating device is an electrical resistance heater with at least one heating resistor. 
     
     
         11 . The air dehumidification unit of  claim 1 , wherein the heating device is at least one electrical fiber element with a positive temperature coefficient. 
     
     
         12 . The air dehumidification unit of  claim 11 , wherein the at least one electrical fiber element with the positive temperature coefficient is at least one of woven and molded into the drainage channel. 
     
     
         13 . The air dehumidification unit of  claim 1 , wherein the drainage channel is a hose formed from a plastic material. 
     
     
         14 . The air dehumidification unit of  claim 1 , wherein the heating device is connected to at least one of a control device and a regulating device that enables operation of the heating device in one of a constant heating mode and a heating mode controlled by an external signal. 
     
     
         15 . The air dehumidification unit of  claim 1 , wherein the heating device is a high pressure heat pump line of a heat pump system disposed adjacent the drainage channel. 
     
     
         16 . A method for dehumidifying air in a heating, ventilating, and air conditioning system of a motor vehicle, comprising the steps of:
 providing an air dehumidification unit including an evaporator disposed in an air flow channel and a drainage channel having an internal volume coupled to the air flow channel;   facilitating a flow of air through the air dehumidification unit which causes humidity in the flow of air through the air dehumidification unit to condense at the evaporator and a fluid to flow into the drainage channel; and   heating an internal volume of the drainage channel from outside of the internal volume of the drainage channel.   
     
     
         17 . The method of  claim 16 , wherein the heating device is operated in one of a constant heating mode and a heating mode controlled by an external signal. 
     
     
         18 . The method of  claim 17 , wherein the external signal depends upon at least one of at least one measured value of an ambient temperature, a position of a recirculating air damper door, and at least one measurement of the humidity. 
     
     
         19 . The method of  claim 16 , wherein a direct heating of the drainage channel is performed when at least a portion of the internal volume of the drainage channel includes ice formed therein. 
     
     
         20 . The method of  claim 16 , wherein an indirect heating of the drainage channel is performed to minimize electric power consumption and militate against a formation of ice in the drainage channel.