Shell and tube isolation in heat exchanger

Abstract

A heat exchanger includes a heat exchanger shell formed from a first metal material, and a plurality of heat exchanger tubes extending through a plurality of tube openings in the heat exchanger shell. The plurality of heat exchanger tubes are formed from a second metal material different from the first metal material. A galvanic isolator is located at each tube opening of the plurality of tube openings, radially between the tube opening and the corresponding heat exchanger tube of the plurality of heat exchanger tubes. The galvanic isolator is configured to mitigate a galvanic reaction between the heat exchanger shell and the plurality of heat exchanger tubes.

What is claimed is: 
     
         1 . A heat exchanger comprising:
 a heat exchanger shell formed from a first metal material;   a plurality of heat exchanger tubes extending through a plurality of tube openings in the heat exchanger shell, the plurality of heat exchanger tubes formed from a second metal material different from the first metal material; and   a galvanic isolator disposed at each tube opening of the plurality of tube openings, radially between the tube opening and the corresponding heat exchanger tube of the plurality of heat exchanger tubes, the galvanic isolator configured to mitigate a galvanic reaction between the heat exchanger shell and the plurality of heat exchanger tubes.   
     
     
         2 . The heat exchanger of  claim 1 , wherein:
 the heat exchanger shell is formed from steel; and   the plurality of heat exchanger tubes are formed from aluminum.   
     
     
         3 . The heat exchanger of  claim 1 , wherein the galvanic isolator is formed from a non-metallic material. 
     
     
         4 . The heat exchanger of  claim 1 , wherein the galvanic isolator is sleeve installed to one of the plurality of tube openings or the plurality of heat exchanger tubes prior to installation of the plurality of heat exchanger tubes into the plurality of tube openings. 
     
     
         5 . The heat exchanger of  claim 1 , wherein the galvanic isolator is a coating applied to one of the plurality of tube openings or the plurality of heat exchanger tubes prior to installation of the plurality of heat exchanger tubes into the plurality of tube openings. 
     
     
         6 . The heat exchanger of  claim 5 , wherein the coating is a polytetrafluoroethylene (PTFE) material. 
     
     
         7 . The heat exchanger of  claim 1 , wherein the galvanic isolator has a thickness in a range of 0.0005 to 0.001 inches. 
     
     
         8 . The heat exchanger of  claim 1 , wherein installation of the plurality of heat exchanger tubes into the plurality of tube openings seals the plurality of tube openings. 
     
     
         9 . A chiller system comprising:
 a refrigerant circuit having a flow of refrigerant circulating therethrough;   a fluid circuit having a flow of heat transfer fluid circulating therethrough, the fluid circuit operably connected to the refrigerant circuit at a heat exchanger assembly to transfer thermal energy between the flow of refrigerant and the fluid circuit, the heat exchanger assembly comprising:   a heat exchanger shell formed from a first metal material;
 a plurality of heat exchanger tubes extending through a plurality of tube openings in the heat exchanger shell, the plurality of heat exchanger tubes formed from a second metal material different from the first metal material; and 
 a galvanic isolator disposed at each tube opening of the plurality of tube openings, radially between the tube opening and the corresponding evaporator tube of the plurality of heat exchanger tubes, the galvanic isolator configured to mitigate a galvanic reaction between the heat exchanger shell and the plurality of heat exchanger tubes. 
   
     
     
         10 . The chiller system of  claim 9 , wherein:
 the heat exchanger shell is formed from steel; and   the plurality of heat exchanger tubes are formed from aluminum.   
     
     
         11 . The chiller system of  claim 9 , wherein the galvanic isolator is formed from a non-metallic material. 
     
     
         12 . The chiller system of  claim 9 , wherein the galvanic isolator is sleeve installed to one of the plurality of tube openings or the plurality of heat exchanger tubes prior to installation of the plurality of heat exchanger tubes into the plurality of tube openings. 
     
     
         13 . The chiller system of  claim 9 , wherein the galvanic isolator is a coating applied to one of the plurality of tube openings or the plurality of heat exchanger tubes prior to installation of the plurality of heat exchanger tubes into the plurality of tube openings. 
     
     
         14 . The chiller system of  claim 13 , wherein the coating is a polytetrafluoroethylene (PTFE) material. 
     
     
         15 . The chiller system of  claim 9 , wherein the galvanic isolator has a thickness in a range of 0.0005 to 0.001 inches. 
     
     
         16 . The chiller system of  claim 9 , wherein installation of the plurality of heat exchanger tubes into the plurality of tube openings seals the plurality of tube openings. 
     
     
         17 . The chiller system of  claim 9 , wherein the heat transfer fluid is water. 
     
     
         18 . A method of assembling a heat exchanger comprising:
 defining a heat exchanger shell formed from a first metal material, the heat exchanger shell having a plurality of tube openings formed therein;   providing a plurality of heat exchanger tubes formed from a second metal material different from the first metal material;   installing a non-metallic galvanic isolator to one of an opening wall of the plurality of tube openings or the plurality of heat exchanger tubes; and   installing the plurality of heat exchanger tubes into the plurality of tube openings, such that the galvanic isolator is disposed radially between the heat exchanger tube and the opening wall.   
     
     
         19 . The method of  claim 18 , wherein the galvanic isolator is a polymeric sleeve. 
     
     
         20 . The method of  claim 18 , wherein the galvanic isolator is a coating applied to one of the opening wall or the heat exchanger tube.