Exhaust assembly heat mitigation system

Abstract

This disclosure describes, in part, systems and structures for an exhaust assembly that includes an exhaust tube and an insulation structure surrounding the exhaust tube. The insulation structure is offset from the exhaust tube to create an air gap around the exhaust tube and the insulation structure. The air gap is used to transport forced air by a fan system to mitigate and remove heat from the exhaust tube to a disposal location. The insulation structure includes an inner shell and an outer shell that contain an insulation component to provide a reduced surface temperature during steady state operation within a threshold range.

What is claimed is: 
     
         1 . An exhaust assembly comprising:
 an exhaust tube defining a substantially central axis, wherein the exhaust tube is configured to direct an exhaust gas away from an engine to which the exhaust tube is fluidly connected;   an insulation structure positioned concentrically around the exhaust tube, the insulation structure including:
 a standoff coupled to the exhaust tube and providing an air gap between the exhaust tube and the insulation structure; 
 an inner shell coupled to the standoff and concentric about the exhaust tube; 
 an outer shell concentric about the inner shell; and 
 an insulation layer disposed between the inner shell and the outer shell; and 
   a forced air system that drives air through the air gap along a length of the exhaust tube.   
     
     
         2 . The exhaust assembly of  claim 1 , wherein the insulation layer comprises aerogel. 
     
     
         3 . The exhaust assembly of  claim 1 , wherein the standoff comprises a porous metal mesh disposed in the air gap between the inner shell and the exhaust tube. 
     
     
         4 . The exhaust assembly of  claim 1 , wherein the insulation layer comprises rock wool insulation. 
     
     
         5 . The exhaust assembly of  claim 1 , wherein the exhaust gas travels along the exhaust tube in a first direction and the forced air system drives the air in a second direction opposite the first direction. 
     
     
         6 . The exhaust assembly of  claim 1 , wherein the exhaust gas travels along the exhaust tube in a first direction and the forced air system drives the air in a second direction parallel to the first direction. 
     
     
         7 . The exhaust assembly of  claim 1 , wherein the forced air system comprises a fan at a first end of the insulation structure configured to pull air through the air gap from a second end to the first end. 
     
     
         8 . An exhaust insulation system comprising:
 an inner shell disposed radially outward from an exhaust tube;   an outer shell disposed radially outward from the inner shell;   an insulation layer disposed between the inner shell and the outer shell;   a support coupled between the inner shell and the exhaust tube that supports the inner shell and provides an air gap between the inner shell and the exhaust tube; and   a forced air system comprising:
 a first opening at a first end of the exhaust insulation system providing access to the air gap; 
 a second opening at a second end of the exhaust insulation system providing access to the air gap; and 
 a fan positioned adjacent the first opening and configured to drive air through the air gap. 
   
     
     
         9 . The exhaust insulation system of  claim 8 , wherein the insulation layer comprises shredded aerogel insulation. 
     
     
         10 . The exhaust insulation system of  claim 8 , wherein the fan is configured to drive the air through the air gap in a first direction opposite a direction of travel of exhaust within the exhaust tube. 
     
     
         11 . The exhaust insulation system of  claim 8 , wherein the fan is configured to drive the air through the air gap in a second direction opposite a direction of travel of exhaust within the exhaust tube. 
     
     
         12 . The exhaust insulation system of  claim 8 , wherein the support comprises metal fins coupled between the exhaust tube and the inner shell. 
     
     
         13 . The exhaust insulation system of  claim 8 , further comprising a radiation shield positioned in the air gap between the exhaust tube and the inner shell, the radiation shield defining one or more openings. 
     
     
         14 . The exhaust insulation system of  claim 8 , wherein the support comprises a metal mesh. 
     
     
         15 . The exhaust insulation system of  claim 8 , wherein the inner shell and the outer shell define a plurality of openings along a length of the exhaust tube. 
     
     
         16 . A system comprising:
 an internal combustion engine; and   an exhaust assembly fluidly connected with the internal combustion engine, wherein the exhaust assembly comprises:
 an exhaust tube oriented about an axis, wherein an exhaust gas is configured to flow through the exhaust tube away from the internal combustion engine; 
 an insulation structure positioned concentrically around the exhaust tube, the insulation structure including:
 a standoff coupled to the exhaust tube and providing an air gap between the exhaust tube and the insulation structure; 
 an inner shell coupled to the standoff and concentric about the exhaust tube; 
 an outer shell concentric about the inner shell; and 
 an insulation layer disposed between the inner shell and the outer shell; and 
 
 a forced air system that drives air through the air gap along a length of the exhaust tube. 
   
     
     
         17 . The system of  claim 16 , wherein the insulation layer comprises a shredded aerogel insulation. 
     
     
         18 . The system of  claim 16 , wherein the standoff comprises a porous metal mesh. 
     
     
         19 . The system of  claim 16 , wherein the forced air system is configured to drive the air through the air gap in a direction parallel with a direction of travel of the exhaust gas. 
     
     
         20 . The system of  claim 16 , wherein the forced air system is configured to drive the air through the air gap in a direction opposite a direction of travel of the exhaust gas.