Multichannel heat exchanger fins

Abstract

Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and heat exchangers are provided that include nubbed, collared, and/or flapped fins. In certain embodiments, the fins include openings or slots with protrusions for spacing multichannel tubes from the fins. During assembly, the protrusions may be deformed by the tubes. Braze alloy may be positioned in the gaps created by the protrusions to affix the multichannel tubes to the fins. In other embodiments, the fins include flaps or collars designed to interface with the multichannel tubes. In these embodiments, the tubes may be expanded into the fins.

1 . A heat exchanger comprising:
 a first manifold;   a second manifold;   a plurality of multichannel tubes in fluid communication with the first and second manifolds, each multichannel tube having a plurality of generally parallel flow paths extending through a cross section of the multichannel tube;   a plurality of fins coupled to the plurality of multichannel tubes, the fins having openings disposed around the cross sections; and   a plurality of projections protruding into the openings to contact the multichannel tubes within the openings.   
     
     
         2 . The heat exchanger of  claim 1 , comprising braze alloy disposed between the projections to affix the multichannel tubes to the fins. 
     
     
         3 . The heat exchanger of  claim 1 , wherein the plurality of multichannel tubes are coated with a braze alloy, and wherein the plurality of projections are configured to draw the braze alloy from the tubes by capillary action. 
     
     
         4 . The heat exchanger of  claim 1 , wherein the projections are configured to deform upon contacting one of the multichannel tubes. 
     
     
         5 . The heat exchanger of  claim 1 , wherein the openings encircle the cross sections of the multichannel tubes. 
     
     
         6 . The heat exchanger of  claim 1 , wherein the projections comprise nubs that define an internal height of the openings that is smaller than a cross sectional height of the multichannel tubes. 
     
     
         7 . The heat exchanger of  claim 1 , wherein the projections comprise flaps that extend into the openings from opposite sides of the openings to produce an interference fit between the multichannel tubes and the fins. 
     
     
         8 . The heat exchanger of  claim 1 , wherein the plurality of multichannel tubes are expanded into the fins. 
     
     
         9 . A heat exchanger fin comprising:
 a sheet of thermally conductive material;   elongated openings formed in the sheet for receiving multichannel tubes; and   a plurality of projections extending into each of the openings for contacting the multichannel tubes upon insertion through the openings.   
     
     
         10 . The heat exchanger fin of  claim 9 , wherein each of the openings is completely surrounded by the sheet of thermally conductive material. 
     
     
         11 . The heat exchanger fin of  claim 9 , wherein the plurality of projections are integrally formed in the sheet of thermally conductive material. 
     
     
         12 . The heat exchanger fin of  claim 9 , wherein the plurality of projections comprises a plurality of nubs extending into each of the openings for contacting the multichannel tubes upon insertion through the openings. 
     
     
         13 . The heat exchanger fin of  claim 12 , wherein the nubs are aligned in pairs, with each nub of a pair extending towards the other nub of the pair from an opposite side of the opening. 
     
     
         14 . The heat exchanger fin of  claim 9 , wherein the plurality of projections comprises flaps extending into the openings from the sheet and separated from one another around the circumferences of the openings. 
     
     
         15 . A method for making a heat exchanger comprising:
 inserting a multichannel tube coated with a braze alloy through a plurality of openings each disposed on a sheet of thermally conductive material with a plurality of projections extending into the opening to contact the multichannel tube; and   conveying the multichannel tube and the sheets of thermally conductive material through an oven to permanently join the multichannel tube to the sheets of thermally conductive material by retaining the braze alloy between the plurality of projections.   
     
     
         16 . The method of  claim 15 , wherein inserting a multichannel tube comprises deforming at least one projection with the multichannel tube. 
     
     
         17 . The method of  claim 15 , wherein conveying the multichannel tube and the sheets of thermally conductive material through an oven comprises drawing the braze alloy from the multichannel tube into spaces between the plurality of projections. 
     
     
         18 . The method of  claim 15 , comprising forming the plurality of openings within the sheets of thermally conductive material, wherein forming the plurality of openings comprises forming flaps extending into the plurality of openings, wherein the flaps are designed to interface with the multichannel tube. 
     
     
         19 . The method of  claim 15 , comprising forming the plurality of openings within the sheets of thermally conductive material, wherein forming the plurality of openings comprises forming nubs extending into the plurality of openings to create spaces therebetween for receiving the braze alloy. 
     
     
         20 . The method of  claim 15 , comprising inserting an end of the multichannel tube into a header and permanently joining the multichannel tube and the header.