Double-wall, vented heat exchanger

Abstract

A plate heat exchanger includes a plurality of plate pairs for providing a flow path for two fluids. The plate heat exchanger has an inlet and an outlet for each of the two fluids, wherein facing surfaces of two adjacent plate pairs of the plurality of plate pairs defines a flow path for a first fluid. The opposite surface of one of the two adjacent plate pairs and a facing surface of another adjacent plate pair from the plurality of plate pairs provides a flow path for a second fluid. The first fluid and the second fluid flowing along their respective flow paths are maintained in thermal communication with each other. A predetermined vent path is formed in at least one of the facing surfaces of each plate pair capable of venting each fluid exterior of the heat exchanger.

1 . A plate heat exchanger comprising: 
 a plurality of nested pairs of plates, each plate of the plurality of pairs of plates having opposed surfaces and perimeter flanges and having substantially similar surface profiles, each plate pair forming a substantially conformal fit between contacting surfaces when pressed together, opposed surfaces of each plate pair providing a portion of at least one flow path for each of at least two fluids, wherein facing surfaces and perimeter flanges of adjacent plate pairs of the plurality of plate pairs provide a flow path boundary for two fluids of the at least two fluids, and wherein opposed surfaces of at least one plate pair of each pair of adjacent plate pairs provide a flow path boundary for two fluids of the at least two fluids, the at least one plate pair having a high thermal conductivity and providing a portion of the flow path boundary for two fluids of the at least two fluids, thereby providing thermal communication between the two fluids on the opposed surfaces of the plate;    an inlet and outlet for each fluid of the at least two fluids, the inlet and outlet for each fluid being in fluid communication with each flow path for said fluid; and    wherein a predetermined vent path is formed in at least one of the facing surfaces of each plate pair capable of venting each fluid exterior of the perimeter flanges.    
   
   
       2 . The plate heat exchanger of  claim 1  wherein an internal leakage of fluid between adjacent plate pairs or between adjacent plates of adjacent plate pairs flows along a vent path and is visually evident exterior of the perimeter flanges when the heat exchanger is pressurized to less than about 400 psi for a predetermined time duration.  
   
   
       3 . The plate heat exchanger of  claim 2  wherein the heat exchanger is pressurized to less than about 50 psi.  
   
   
       4 . The plate heat exchanger of  claim 3  wherein the heat exchanger is pressurized to about 1 psi.  
   
   
       5 . The plate heat exchanger of  claim 1  wherein at least a portion of one of the contacting surfaces of each plate pair includes a surface treatment.  
   
   
       6 . The plate heat exchanger of  claim 1  wherein the vent path does not coincide with nodal points of contact between opposed surfaces of adjacent plate pairs.  
   
   
       7 . The plate heat exchanger of  claim 6  wherein the vent path extends in a substantially linear path toward a perimeter flange.  
   
   
       8 . The plate heat exchanger of  claim 6  wherein the linear path extends in a curved path toward a perimeter flange.  
   
   
       9 . The plate heat exchanger of  claim 6  wherein the vent path includes a plurality of paths toward a perimeter flange.  
   
   
       10 . The plate heat exchanger of  claim 1  wherein each adjacent pair of plate pairs includes a plurality of ports for providing a flow channel for at least one fluid through the adjacent pair of plate pairs, each port of the plurality of ports having a double seal.  
   
   
       11 . The plate heat exchanger of  claim 10  wherein each port has at least two surrounding embossed regions formed in the outermost opposed plates of the adjacent plate pair in fluid communication with the vent path.  
   
   
       12 . The plate heat exchanger of  claim 1  wherein the plate heat exchanger is of brazed construction comprising the insertion of at least one foil plate between the adjacent plate pairs of the plurality of plate pairs, the at least one foil plate becoming molten and flowing between adjacent plates of the plurality of plates to form brazed nodal contacts between facing surfaces of the adjacent plate pairs of the plurality of plate pairs when the plate heat exchanger is heated to a predetermined temperature below the melting point of the adjacent plate pairs of the plurality of plates, but above the melting temperature of the at least one foil plate.  
   
   
       13 . The plate heat exchanger of  claim 12  wherein predetermined regions of plate surfaces are selectively treated to prevent brazed contacts in the predetermined regions.  
   
   
       14 . The plate heat exchanger of  claim 13  wherein at least one portion of at least one surface of at least one perimeter flange of the contacting surfaces between the plate pairs are selectively treated to prevent the formation of brazed contacts.  
   
   
       15 . The plate heat exchanger of  claim 14  wherein a focused inspection area substantially coincides with the at least one treated portion.  
   
   
       16 . The plate heat exchanger of  claim 15  wherein the focused inspection area is an embossed region formed in the at least one perimeter flange.  
   
   
       17 . A method making plates for a plate heat exchanger, the steps comprising: 
 providing a plurality of nested pairs of plates, each plate of the plurality of pairs of plates having opposed surfaces and perimeter flanges and having substantially similar surface profiles, each plate pair forming a substantially conformal fit between contacting surfaces when pressed together, opposed surfaces of each plate pair providing a portion of at least one flow path for each of at least two fluids, wherein facing surfaces and perimeter flanges of adjacent plate pairs of the plurality of plate pairs provide a flow path boundary for two fluids of the at least two fluids, and wherein opposed surfaces of at least one plate pair of each pair of adjacent plate pairs provide a flow path boundary for two fluids of the at least two fluids, the at least one plate pair having a high thermal conductivity and providing a portion of the flow path boundary for two fluids of the at least two fluids, thereby providing thermal communication between the two fluids on the opposed surfaces of the plate; each plate of plurality of plates including the step of: 
 forming a plurality of apertures in the plate, at least two of the apertures having an embossed region surrounding the apertures, each embossed region defining a path for venting fluids of the at least two fluids leaking between nested plate pairs along aligned apertures of the plurality of apertures;  
 forming at least one primary vent path in the plate, the at least one primary vent path in fluid communication with the at least two embossed regions for venting the at least two fluids exterior of the perimeter flanges; and  
 selectively applying a surface treatment to at least one surface and perimeter flanges of at least one plate, the at least one surface corresponding to a contacting surface of a plate pair.  
   
   
   
       18 . The method of  claim 17  wherein the at least one primary vent path does not coincide with nodal connections defined between facing surfaces of adjacent plate pairs of the plurality of plate pairs.  
   
   
       19 . A plate heat exchanger comprising: 
 a plurality of nested pairs of plates, each plate of the plurality of pairs of plates having opposed surfaces and perimeter flanges and having substantially similar surface profiles, each plate pair forming a substantially conformal fit between contacting surfaces when pressed together, opposed surfaces of each plate pair providing a portion of at least one flow path for each of at least two fluids, wherein facing surfaces and perimeter flanges of adjacent plate pairs of the plurality of plate pairs provide a flow path boundary for two fluids of the at least two fluids, and wherein opposed surfaces of at least one plate pair of each pair of adjacent plate pairs provide a flow path boundary for two fluids of the at least two fluids, the at least one plate pair having a high thermal conductivity and providing a portion of the flow path boundary for two fluids of the at least two fluids, thereby providing thermal communication between the two fluids on the opposed surfaces of the plate;    an inlet and outlet for each fluid of the at least two fluids, the inlet and outlet for each fluid being in fluid communication with each flow path for said fluid; and    wherein a predetermined vent path is formed in at least one of the facing surfaces of each plate pair capable of venting each fluid exterior of the perimeter flanges.    
   
   
       20 . The plate heat exchanger of  claim 19  wherein each adjacent pair of plate pairs includes a plurality of ports for providing a flow channel for at least one fluid through the adjacent pair of plate pairs, each port of the plurality of ports having a double seal, each port having at least two surrounding embossed regions formed in the outermost opposed plates of the adjacent plate pair to vent two fluids of the at least two fluids leaking along a port between the plates of each adjacent plate pair to the vent path.