Microchannel heat exchanger module design to reduce water entrapment

Abstract

A microchannel heat exchanger has a core having at least one heat exchange tube bank having a plurality of flow channels with a small hydraulic diameter less than 5 mm. A means is provided to reduce the amount of water retained on the external surfaces of the at least one heat exchange tube bank. These means may utilize the incorporation of a particular routing of refrigerant within the heat exchanger, the operation and control of a fan associated with the heat exchanger, or the provision of structure to at least partially block liquid from reaching the heat exchanger tube bank.

1 . A microchannel heat exchanger comprising:
 a heat exchanger core including at least one heat exchange tube bank with heat exchange tubes in the at least one heat exchange tube bank having a plurality of internal parallel flow channels; and   a means to reduce condensate retention within the heat exchanger core.   
     
     
         2 . The heat exchanger as set forth in  claim 1 , wherein said means to reduce condensate retention within the heat exchanger core include routing of the refrigerant flowing inside said heat exchange tubes. 
     
     
         3 . The heat exchanger as set forth in  claim 2 , wherein there are a plurality of said heat exchange tube banks, and refrigerant flows in opposed parallel directions through said plurality of heat exchange tube banks from an inlet manifold, into an intermediate manifold, and from said intermediate manifold to an outlet manifold, said inlet manifold fluidly connected to a first heat exchange tube bank, with both said inlet manifold and said first heat exchange tube bank being located in a bottom section of the heat exchanger to provide a higher temperature refrigerant to the bottom section of the heat exchanger. 
     
     
         4 . The heat exchanger as set forth in  claim 3 , wherein there are more than two of said heat exchange tube banks, with said first heat exchange tube bank being a vertically lowermost of said heat exchange tube banks, and one of intermediate heat exchange tube banks being a vertically uppermost of said heat exchange tube banks. 
     
     
         5 . The heat exchanger as set forth in  claim 3 , wherein there are more than two of said heat exchange tube banks, with said heat exchange tube banks being arranged in a vertically intertwined configuration. 
     
     
         6 . The heat exchanger as set forth in  claim 5 , wherein at least one branch pipe routes refrigerant from one of said heat exchange tube banks to another of said heat exchange tube banks. 
     
     
         7 . The heat exchanger as set forth in  claim 3 , wherein a flow control device for selectively tapping at least a portion of higher temperature refrigerant from an upstream location to a downstream location to provide additional heating at the downstream location is included. 
     
     
         8 . The heat exchanger as set forth in  claim 7 , wherein said downstream location is in an intermediate manifold. 
     
     
         9 . The heat exchanger as set forth in  claim 8 , wherein said intermediate manifold communicates with a vertically lowermost one of said plurality of heat exchange tube banks. 
     
     
         10 . The heat exchanger as set forth in  claim 1 , wherein there is at least one fan associated with the heat exchanger, said at least one fan being operable to move air over said at least one heat exchange tube bank to absorb heat from refrigerant flowing inside said heat exchange tubes, said at least one fan being selectively operable in a reverse direction to move air over said at least one heat exchange tube bank to remove moisture accumulated on external heat exchanger surfaces. 
     
     
         11 . The heat exchanger as set forth in  claim 1 , wherein there is at least one fan associated with the heat exchanger, said at least one fan being operable to move air over said at least one heat exchange tube bank to absorb heat from refrigerant flowing inside said heat exchange tubes, said at least one fan is a variable speed fan and said variable speed fan is selectively and periodically operated at a reduced speed to increase temperature of refrigerant flowing through at least one heat exchange tube bank to remove moisture accumulated on external heat exchanger surfaces. 
     
     
         12 . The heat exchanger as set forth in  claim 1 , wherein there is at least one fan associated with the heat exchanger, said at least one fan being operable to pull air over said at least one heat exchange tube bank to absorb heat from refrigerant flowing inside said heat exchange tubes, said at least one fan to be periodically turned on during prolonged shutdown periods to move air over said at least one heat exchange tube bank to remove moisture accumulated on external heat exchanger surfaces. 
     
     
         13 . The heat exchanger as set forth in  claim 1 , wherein there are at least two fans associated with the heat exchanger, said at least two fans being operable to move air over said at least one heat exchange tube bank to absorb heat from refrigerant flowing inside said heat exchange tubes, and at least one fan of said at least two fans to be selectively and periodically turned off to increase temperature of refrigerant flowing through at least one heat exchange tube bank to remove moisture accumulated on external heat exchanger surfaces. 
     
     
         14 . The heat exchanger as set forth in  claim 1 , wherein there is a frame structure associated with the heat exchanger, said frame structure including a generally solid upper deck and a fan mounted to said frame structure and moving air over said at least one heat exchange tube bank through a fan orifice, and a cover for blocking moisture from entering said fan orifice. 
     
     
         15 . The heat exchanger as set forth in  claim 14 , wherein said cover includes a wire mesh material.