Heat exchanger

Abstract

The invention relates to a heat exchanger, particularly an evaporator for air conditioners in motor vehicles, having a number of heat transfer surfaces made of metal, in particular, aluminum or aluminum compounds. The aim of the invention is to provide this heat exchanger with a surface coating that is improved compared to the prior art. To this end, a number of layers are applied to its heat transfer surfaces, and nanoparticles are used for the coating.

1 . A heat exchanger, in particular an evaporator for air-conditioning systems in motor vehicles, having a number of heat transfer surfaces made from metal, in particular aluminum or aluminum compounds, to which a plurality of layers have been applied, nanoparticles being used for the coating.  
   
   
       2 . The heat exchanger as claimed in  claim 1 , in which each layer contains nanoparticles of different compositions.  
   
   
       3 . The heat exchanger as claimed in  claim 1 , in which at least one layer has corrosion-resistant properties and at least one further layer, preferably arranged thereon, has hydrophilic properties.  
   
   
       4 . The heat exchanger as claimed in  claim 3 , in which the layer with hydrophilic properties has a wetting contact angle with water of less than or equal to 60°, preferably of less than or equal to 40°.  
   
   
       5 . The heat exchanger as claimed in  claim 1 , in which the nanoparticles of organic and/or inorganic compounds of aluminum, silicon, boron and/or transition metals, preferably from transition groups IV and V of the periodic system, and/or cerium dissolved and/or dispersed in inorganic and/or organic solvents are used for the coating.  
   
   
       6 . The heat exchanger as claimed in  claim 1 , in which each layer thickness amounts to less than 1.5 μm or equal to 1.5 μm, preferably less than 1 μm or equal to 1 μm, and in which the total layer thickness amounts to less than 5 μm or equal to 5 μm.  
   
   
       7 . A process for the surface treatment of heat exchangers, in particular as claimed in  claim 1 , in which a plurality of layers are applied to a number of heat transfer surfaces made from metal, in particular aluminum or aluminum compounds, with nanoparticles being used for the coating.  
   
   
       8 . The process as claimed in  claim 7 , in which the nanoparticles of organic and/or inorganic compounds of aluminum, silicon, boron and/or transition metals, preferably from transition groups IV and V of the periodic system, and/or cerium dispersed and/or dissolved in inorganic and/or organic solvents are used for the coating.  
   
   
       9 . The process as claimed in  claim 7 , in which the layers are applied by dipping, flooding or spraying, with the individual layers being applied in direct succession without any intermediate drying.  
   
   
       10 . The process as claimed in  claim 7 , in which the layers are applied by dipping, flooding or spraying, with the individual layers being applied in separate treatment steps in each case with intermediate drying.