Controlling exhaust temperatures

Abstract

An exhaust manifold cooling jacket has internal passages for the circulation of liquid coolant and encloses an exhaust manifold such that a gap is created between the exhaust manifold and cooling jacket. Flowing coolant through the jacket regulates outer jacket temperature while enabling high intra-manifold exhaust gas temperatures for thorough intra-manifold combustion and improved emissions. A liquid-cooled exhaust system includes a turbocharger disposed between manifold and elbow, with liquid coolant flowing from manifold to elbow through the turbocharger. Another liquid-cooled exhaust manifold contains an internal exhaust combustion catalyst wrapped in an insulating blanket. In some marine applications, seawater or fresh water coolant is discharged into the exhaust gas stream at an attached exhaust elbow.

1 - 18 . (canceled) 
     
     
         19 . A marine engine exhaust system defining an exhaust passage extending from an engine exhaust manifold inlet to an exhaust system outlet, the exhaust system comprising:
 a liquid-cooled exhaust manifold configured to merge multiple exhaust flows into a merged exhaust flow, the exhaust manifold configured to be coupled to an engine cylinder head;   an exhaust coolant injector disposed downstream of the manifold and configured to inject cooling fluid into the merged exhaust flow; and   a turbocharger disposed between the manifold and the coolant injector, and through which the merged exhaust passes,   wherein the turbocharger comprises a liquid-cooled turbocharger housing through which the cooling fluid flows before entering the exhaust coolant injector.   
     
     
         20 . The marine engine exhaust system of  claim 19 , wherein the cooling fluid flows through the manifold before entering the turbocharger housing. 
     
     
         21 . The marine engine exhaust system of  claim 19 , wherein the cooling fluid flows through a channel within a jacket that surrounds the manifold. 
     
     
         22 . The marine engine exhaust system of  claim 19  wherein the cooling fluid enters the exhaust system at an inlet defined by the manifold and spaced from the engine, such that during operation the cooling fluid enters the manifold away from the engine cylinder head. 
     
     
         23 . The marine engine exhaust system of  claim 19 , further comprising a catalytic conversion element arranged to intercept and catalyze the merged exhaust flow and disposed upstream of the exhaust coolant injector. 
     
     
         24 . The marine engine exhaust system of  claim 23 , wherein the catalytic conversion element is disposed within the manifold. 
     
     
         25 . The marine engine exhaust system of  claim 23 , wherein the catalytic conversion element is disposed within a housing cooled by the cooling fluid. 
     
     
         26 . The marine engine exhaust system of  claim 25  wherein a major length of the catalytic conversion element is arranged to be substantially surrounded by a flow of the cooling fluid. 
     
     
         27 . The marine engine exhaust system of  claim 19 , wherein the turbocharger is disposed immediately downstream of the manifold.