Heat Exchanger for Heating a Fluid Using Exhaust Gas

Abstract

A rapid warm-up heat exchanger for heating a fluid using exhaust gas includes multiple plate pairs that are joined by braze joints to form a stack. A fluid inlet manifold and a fluid manifold extend through the stack, and each one of the plate pairs defines a tortuous flow path for the fluid that extends between the fluid inlet and fluid outlet manifolds. A housing surrounds the stack, and together the housing and the stack define an exhaust flow path in spaces provided between adjacent plate pairs. A valve element can be provided within the housing in order to selectively direct exhaust flow through the exhaust flow path.

What is claimed is: 
     
         1 . A heat exchanger for heating a fluid using exhaust gas, comprising:
 a plurality of plate pairs joined by braze joints to form a stack;   a fluid inlet manifold and a fluid outlet manifold extending through the stack, each one of the plate pairs defining a tortuous flow path for the fluid extending between the fluid inlet manifold and the fluid outlet manifold; and   a housing surrounding the stack, the housing and the stack together defining a generally U-shaped exhaust flow path in spaces provided between adjacent plate pairs.   
     
     
         2 . The heat exchanger of  claim 1 , wherein the U-shaped exhaust flow path surrounds the inlet and outlet fluid manifolds. 
     
     
         3 . The heat exchanger of  claim 1 , wherein the housing comprises at least two parts and wherein one or more of the at least two parts is joined to the stack by braze joints. 
     
     
         4 . The heat exchanger of  claim 3 , wherein the braze joints between the pluralities of plate pairs and the braze joints joining the one or more of the housing parts to the stack are formed in a single brazing operation. 
     
     
         5 . The heat exchanger of  claim 1 , further comprising a plurality of turbulation features extending from plates of the plate pairs into the spaces between adjacent plate pairs. 
     
     
         6 . The heat exchanger of  claim 1 , wherein the housing includes a wall adjacent to an edge of each of the plurality of plate pairs, said wall comprising:
 an inlet aperture to deliver exhaust gas to the exhaust flow path;   an outlet aperture spaced apart from the inlet aperture to receive exhaust gas from the exhaust flow path; and   a wall section extending between the inlet aperture and the outlet aperture, the fluid inlet and outlet manifolds being arranged immediately adjacent the wall section.   
     
     
         7 . The heat exchanger of  claim 6 , wherein the housing comprises:
 a first housing part containing the inlet aperture; and   a second housing part distinct from the first housing part, the second housing part containing the outlet aperture, wherein the wall section between the inlet aperture and the outlet aperture is defined by portions of both the first housing part and the second housing part.   
     
     
         8 . The heat exchanger of  claim 1 , wherein the housing includes:
 a cylindrical exhaust inlet;   a cylindrical exhaust outlet; and   a linear flow path extending between the cylindrical exhaust inlet and the cylindrical exhaust outlet, the linear flow path bypassing the generally U-shaped exhaust flow path.   
     
     
         9 . The heat exchanger of  claim 8 , further comprising a valve element arranged along the linear flow path to selectively direct exhaust gas along the generally U-shaped exhaust flow path. 
     
     
         10 . The heat exchanger of  claim 9 , wherein the valve element is rotatable about an axis extending through the housing. 
     
     
         11 . The heat exchanger of  claim 7 , wherein the housing comprises:
 a first housing part defining a first portion of the cylindrical exhaust inlet and a first portion of the cylindrical exhaust outlet; and   a second housing part defining a second portion of the cylindrical exhaust inlet and a second portion of the cylindrical exhaust outlet.   
     
     
         12 . The heat exchanger of  claim 11 , wherein at least one of the first and second housing parts is joined to the stack by braze joints. 
     
     
         13 . The heat exchanger of  claim 11 , wherein both the first and second housing parts are joined to the stack by braze joints. 
     
     
         14 . The heat exchanger of  claim 11 , wherein the first and second housing parts are joined together in a plane that is parallel to, and located between, a top-most plate of the plurality of plate pairs and a bottom-most plate of the plurality of plate pairs. 
     
     
         15 . The heat exchanger of  claim 11 , wherein the housing further comprises a third housing part defining a third portion of the cylindrical exhaust inlet and a third portion of the cylindrical exhaust outlet. 
     
     
         16 . The heat exchanger of  claim 15 , wherein the third housing part is joined to both the first and second housing parts in a plane that is parallel to a stacking direction of the plurality of plate pairs. 
     
     
         17 . A heat exchanger for heating a fluid using exhaust gas, comprising:
 a plurality of plate pairs joined by braze joints to form a stack, spaces between adjacent plate pairs at least partially defining a flow path for the exhaust gas;   a housing surrounding the plurality of plate pairs to bound the exhaust gas within the heat exchanger, the housing comprising a first housing part and a second housing part, at least one of the first and second housing parts being joined to the stack by braze joints; and   a valve element arranged within the housing to selectively divert exhaust gas so as to bypass the spaces between the plurality of plate pairs.   
     
     
         18 . The heat exchanger of  claim 17 , wherein the housing includes a cylindrical exhaust inlet and a cylindrical exhaust outlet, a first portion of the cylindrical exhaust inlet and a first portion of the cylindrical exhaust outlet being defined by the first housing part and a second portion of the cylindrical exhaust inlet and a second portion of the cylindrical exhaust outlet being defined by the second housing part. 
     
     
         19 . The heat exchanger of  claim 18 , wherein the housing further comprises a third housing part defining a third portion of the cylindrical exhaust inlet and a third portion of the cylindrical exhaust outlet. 
     
     
         20 . The heat exchanger of  claim 19 , wherein the first and second portions of the cylindrical exhaust inlet and outlet each span an arc length of 90 degrees and wherein the third portions of the cylindrical exhaust inlet and outlet each span an arc length of 180 degrees.