Heated flash-boiling doser with integrated helix

A reducing agent mixer for use in an exhaust aftertreatment system for an over-the-road vehicle, the reducing agent mixer comprising

• a mixing can defining at least a portion of an exhaust passageway for receiving a flow of exhaust gases therein, and
• a flash-boil doser mounted to the mixing can and configured to heat a reducing agent to drive the reducing agent to a predetermined pressure and to inject the reducing agent into the exhaust passageway of the mixing can, the flash-boil doser comprising
• a doser body including a housing and a heat exchanger assembly, the heat exchanger assembly arranged in the housing and configured to heat the reducing agent thereby increasing a pressure within the heat exchanger assembly to drive injection of the reducing agent into the exhaust passageway,
• a doser inlet coupled to the doser body that defines an inlet passageway that opens into the heat exchanger assembly to admit reducing agent from an associated reducing agent tank, and
• a doser outlet coupled to the doser body that defines an outlet passageway that opens from the heat exchanger assembly into the exhaust passageway, the doser outlet spaced apart axially from the doser inlet relative to a doser axis of the flash-boil doser,
• wherein the heat exchanger assembly includes (i) an outer sleeve shaped to define a spiral channel that wraps around the doser axis and opens toward the doser axis, (ii) an inner sleeve arranged in the outer sleeve to close the spiral channel to form a helical passageway between the outer sleeve and the inner sleeve that is in fluid communication with the inlet and outlet passageways, and (iii) at least one heater arranged around an outer surface of the outer sleeve and configured to conductively heat the outer sleeve to heat the reducing agent in the helical passageway, and
• wherein the doser outlet includes a pressure-activated outlet valve that blocks or allows flow through the outlet passageway, the pressure-activated outlet valve configured to move from a normally-closed position to an open position when the predetermined pressure within the helical passageway is reached to discharge the heated reducing agent from the helical passageway through the outlet passageway and into the exhaust passageway for mixing with the exhaust gases therein during use of the flash-boil doser in the exhaust aftertreatment system.

An over-the-road vehicle, the vehicle comprising

• an internal combustion engine configured to produce a flow of exhaust gases that are conducted through an exhaust passageway defined by an exhaust conduit, and
• an exhaust aftertreatment system configured to treat the flow of exhaust gases, the system comprising
• a reducing agent tank formed to store a reducing agent therein,
• a mixing can defining at least a portion of the exhaust passageway for receiving the flow of exhaust gases therein, and
• a flash-boil doser mounted to the mixing can and configured to heat the reducing agent to drive the reducing agent to a predetermined pressure and to inject the reducing agent into the exhaust passageway of the mixing can, the flash-boil doser comprising
• a doser body including a housing and a heat exchanger assembly, the heat exchanger assembly arranged in the housing and configured to heat the reducing agent thereby increasing a pressure within the heat exchanger assembly to drive injection of the reducing agent into the exhaust passageway,
• a doser inlet coupled to the doser body that defines an inlet passageway that opens into the heat exchanger assembly to admit reducing agent from the reducing agent tank, and
• a doser outlet coupled to the doser body that defines an outlet passageway that opens from the heat exchanger assembly into the exhaust passageway, the doser outlet spaced apart axially from the doser inlet relative to a doser axis of the flash-boil doser,
• wherein the heat exchanger assembly includes (i) an outer sleeve shaped to define a spiral channel that wraps around the doser axis and opens toward the doser axis, (ii) an inner sleeve arranged in the outer sleeve to close the spiral channel to form a helical passageway between the outer sleeve and the inner sleeve that is in fluid communication with the inlet and outlet passageways, and (iii) at least one heater arranged around an outer surface of the outer sleeve and configured to conductively heat the outer sleeve to heat the reducing agent in the helical passageway, and
• wherein the doser outlet includes a pressure-activated outlet valve that blocks or allows flow through the outlet passageway, the pressure-activated outlet valve configured to move from a normally-closed position to an open position when a predetermined pressure within the helical passageway is reached to discharge the heated reducing agent from the helical passageway through the outlet passageway and into the exhaust passageway for mixing with the exhaust gases therein during use of the flash-boil doser in the exhaust aftertreatment system.