Exhaust mixer element and method for mixing

Abstract

According to one aspect of the invention, a mixer element to be placed between an internal combustion engine exhaust manifold and catalytic converter is provided. The mixer element includes a tubular conduit that receives an exhaust gas flow from the internal combustion engine, a first mixer configured to induce a first vortex of the exhaust gas flow in a first rotational direction and an injector disposed in the tubular conduit downstream of the first mixer, the injector being configured to inject a diesel emission fluid flow into the exhaust gas flow. The mixer element also includes a second mixer positioned downstream of the injector and a third mixer positioned downstream of the second mixer, the third mixer being configured to induce a second vortex of the exhaust gas flow and the diesel emission fluid mixture in a second rotational direction, opposite of the first rotational direction.

1 . A mixer element to be placed between an internal combustion engine exhaust manifold and a catalytic converter, the mixer element comprising:
 a tubular conduit that receives an exhaust gas flow from the internal combustion engine;   a first mixer configured to induce a first vortex of the exhaust gas flow in a first rotational direction;   an injector disposed in the tubular conduit downstream of the first mixer, the injector being configured to inject a diesel emission fluid into the exhaust gas flow;   a second mixer positioned downstream of the injector; and   a third mixer positioned downstream of the second mixer, the third mixer being configured to induce a second vortex of the exhaust gas flow and the diesel emission fluid mixture in a second rotational direction, opposite of the first rotational direction.   
     
     
         2 . The mixer element of  claim 1 , wherein the second mixer is configured to induce a radial flow of diesel emission fluid. 
     
     
         3 . The mixer element of  claim 1 , wherein the exhaust gas flow and the diesel fluid mixture flow from the third mixer comprises axial and tangential flow components. 
     
     
         4 . The mixer element of  claim 1 , wherein the first mixer comprises a helical mixer and the third mixer comprises a helical mixer. 
     
     
         5 . The mixer element of  claim 4 , wherein the third mixer has a substantially opposite orientation relative to the first mixer. 
     
     
         6 . The mixer element of  claim 1 , wherein the first mixer comprises a helical mixer and the third mixer comprises a swirl mixer. 
     
     
         7 . The mixer element of  claim 1 , wherein the third mixer comprises swirl blades with thru holes to improve a break up of diesel emission fluid droplets. 
     
     
         8 . The mixer element of  claim 1 , wherein the second mixer comprises an impingement mixer. 
     
     
         9 . The mixer element of  claim 1 , wherein the first vortex comprises a first axial flow component that is less than a second axial flow component, wherein the second axial flow component is closer an axis of the tubular than the first axial conduit flow component. 
     
     
         10 . The mixer element of  claim 1 , wherein the diesel emission fluid comprises urea. 
     
     
         11 . A method for distributing a urea flow within a mixer element, the method comprising:
 receiving an exhaust gas flow from an internal combustion engine into the mixer element;   inducing a first vortex of the exhaust gas flow in a first rotational direction in a first region of the mixer element;   injecting a urea fluid into the exhaust gas flow downstream of the first region;   causing a radial component to the urea fluid and exhaust gas flow in a second region of the mixer element, wherein the second region is downstream of the first region; and   inducing a second vortex of the fluid and exhaust gas flow in a second rotational direction opposite of the first rotational direction, wherein the second vortex is formed downstream of the second region.   
     
     
         12 . The method of  claim 11 , wherein inducing the second vortex of the fluid and exhaust gas flow comprises forming axial and tangential flow components. 
     
     
         13 . The method of  claim 11 , wherein inducing the first vortex through a helical mixer. 
     
     
         14 . The method of  claim 13 , wherein forming the second vortex comprises forming the second vortex by one of a helical mixer and a swirl mixer. 
     
     
         15 . The method of  claim 11 , comprising forming a flow tunnel within the first vortex, wherein a magnitude of a first axial component of the first vortex is less than a magnitude of a second axial component of the exhaust gas flow, wherein the second axial component is closer to an axis of the mixer element than the first axial component. 
     
     
         16 . The method of  claim 11 , wherein forming the second vortex comprises breaking up droplets of the mixture by swirl blades. 
     
     
         17 . The method of  claim 11 , wherein causing the radial component to the urea flow comprises flowing the urea flow through an impingement mixer. 
     
     
         18 . A mixer element to be placed between an exhaust manifold and catalytic converter, the mixer element comprising:
 a tubular that receives an exhaust gas flow;   a first mixer configured to form a first vortex of the exhaust gas flow in a first rotational direction;   an injector disposed on the tubular downstream of the first mixer, the injector being configured to inject a fluid flow into the exhaust gas flow; and   a second mixer positioned downstream of the injector, the second mixer comprising blades, wherein droplets of the fluid flow impact the blades to form small droplets that are directed by the blades to mix with the exhaust gas flow.   
     
     
         19 . The mixer element of  claim 18 , wherein the first mixer comprises a swirl mixer and the second mixer comprises an impingement mixer. 
     
     
         20 . The mixer element of  claim 18 , wherein the fluid flow comprises diesel emission fluid or hydrocarbons.