A vehicle exhaust system component includes an exhaust tube defining an exhaust gas flow path, a side branch tuning tube connected to the exhaust tube at an interface, and a porous structure associated with the exhaust tube to reduce noise generated at the interface. In one example, the porous structure comprises a perforated orifice in the exhaust tube. In another example, the porous structure comprises a mesh screen or mesh sleeve.

A muffler comprises a plurality of tubes disposed within an inner chamber. The holes are at least partially punched through the tubes so that hanging chads extend into the tubes at each hole. The tubes form a serpentine flow-path through the chamber through which exhaust flows. One or more diffusion brackets are also disposed within the chamber and downstream from one or more tube outlets.

An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine, a first treatment element positioned within the exhaust gas pathway, a first injector configured to introduce a first reductant into the exhaust gas pathway upstream of the first treatment element, a second injector configured to introduce a second reductant into the exhaust gas pathway downstream of the first treatment element, a second treatment element positioned within the exhaust gas pathway downstream of the second injector, the second treatment element including a SCR element, and a controller configured to periodically initiate a desulfuring regeneration cycle by increasing a concentration of hydrocarbons in the exhaust gas and increasing the flow of the first reductant through the first injector to oxidize sulfur contamination in the first treatment element at temperatures between 400 and 500 degrees Celsius.

An exhaust duct assembly for conveying exhaust gases emanating from a combustion zone to atmosphere is disclosed. The assembly includes: an exhaust gas outlet for exhausting exhaust gas into the atmosphere; and an acoustic duct portion located upstream of the exhaust gas outlet, the acoustic duct portion having a peripheral wall defining a through-passage arranged and constructed to promote propagation of sound there-through. The acoustic duct portion has a length in a flow direction that is at least 50% of an average hydraulic diameter of the through-passage.

One aspect of the present disclosure provides an exhaust unit including a housing, a wall member, a catalyst, and a muffler chamber. The housing includes a feed inlet and a discharge outlet. The housing is configured such that an exhaust gas of an internal combustion engine is introduced from the feed inlet, and the exhaust gas is discharged from the discharge outlet. The wall member is disposed in the housing, and forms a cylindrical flow path that guides a flow of the exhaust gas introduced from the feed inlet to curve along an outer circumference of an interior of the housing. The catalyst is disposed in the flow path. The muffler chamber communicates with the flow path in a downstream side of the catalyst in the flow path. The wall member serves as a part of a wall that defines an inside and an outside of the muffler chamber.

A substantially metal-free exhaust subsystem includes an exterior housing formed of polymer; and a pipe formed of a layered fibers formed at least partially of glass, and bound by an inorganic binder. The fibers may be glass or ceramic, and may define micro-pores on the interior of the pipe that aid in absorbing acoustic energy, and thereby attenuating exhaust noise.

A muffler comprises a plurality of tubes disposed within an inner chamber. The holes are at least partially punched through the tubes so that hanging chads extend into the tubes at each hole. The tubes form a serpentine flow-path through the chamber through which exhaust flows. One or more diffusion brackets are also disposed within the chamber and downstream from one or more tube outlets.

An apparatus and method for recovering heat and water vapor from a waste gas stream. A waste gas passageway directs waste gas over a plurality of membrane tubes extending across the waste gas passageway. Each of the membrane tubes includes an internal passage separated from the waste gas passageway by a porous membrane. A water supply inlet manifold is connected to each of the plurality of membrane tubes, and configured to introduce water into the internal passages of the membrane tubes. A vacuum source is connected to the water side of the apparatus, and configured to adjust a pressure within the internal passages of the membrane tubes. The water within the internal passages receives heat and water vapor from the waste gas stream across the porous membrane.

An apparatus and method are provided for a drone elimination muffler to attenuate drone exhibited by engine exhaust systems. The drone elimination muffler comprises a hollow canister having a length and a diameter, and a tuned port comprising a first end connected to the canister and a second end connected to the exhaust system. The canister operates in concert with the tuned port as a dampener configured to substantially attenuate exhaust drone, or resonance, at one or more frequencies of engine operation. A valve is configured to switch the drone elimination muffler between a closed state in which the exhaust system operates without acoustic influence due to the drone elimination muffler, and an open state in which the drone elimination muffler directly influences the acoustic properties of the exhaust system.

An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine, a first injector configured to selectively introduce a first reductant into the exhaust gas pathway in response to a sensed temperature of the exhaust gas being within a predetermined temperature range, and a first treatment element positioned within the exhaust gas pathway downstream of the first injector. The first treatment element includes a selective catalytic reduction (SCR) layer, a porous filter substrate, and a precious metal catalyst layer. The system also includes a second injector configured to introduce a second reductant into the exhaust gas pathway downstream of the first treatment element and a second treatment element positioned within the exhaust gas pathway downstream of the second injector. The second treatment element includes a SCR element.