A filtration assembly for removing particulate matter from exhaust gas produced by an engine, including: a first filter; a second filter positioned downstream of the first filter; and a valve including: a first ring defining a plurality of first openings, and a second ring defining a plurality of second openings, the second ring abutting the first ring. The valve is moveable between a closed position in which the plurality of first openings are misaligned with the plurality of second openings to prevent a fluid from flowing through the plurality of first and second openings, and an open position in which the second ring is rotated relative to the first ring such that the plurality of first openings are aligned with the plurality of second openings allowing the fluid to flow therethrough. A first end of the valve is positioned at an outlet of the first filter, and a second end of the valve is positioned at an inlet of the second filter. In the closed position of the valve, substantially all of the exhaust gas flows through the second filter, and in the open position of the valve, at least a portion of the exhaust gas flows through the valve and bypasses the second filter.

A heating system includes at least one electric heater disposed within a fluid flow system and a control device that is configured to determine a temperature of the at least one electric heater based on a model, at least one fluid flow system input, and at least one heater input. The at least one heater input includes at least one physical characteristic of the heating system, the at least one physical characteristic includes at least one of a resistance wire diameter, a heater insulation thickness, a heater sheath thickness, a conductivity, a specific heat and density of the material of the heater, an emissivity of the heater and the fluid flow pathway, and combinations thereof. The control device is configured to provide power to the at least one electric heater based on the temperature of the at least one electric heater.

A heating system includes at least one electric heater disposed within the fluid flow system. A control device includes a microprocessor and is configured to determine a temperature of the at least one electric heater based on a model and at least one input from the fluid flow system. The control device is configured to provide power to the at least one electric heater based on the temperature of the at least one electric heater.

A particulate collection system collects particulates contained in exhaust gas discharged from an internal combustion engine. The particulate collection system includes a first particulate collection filter; a second particulate collection filter capable of storing or radiating heat; a heating member for heating the second particulate collection filter; and a control section which selectively executes collection of particulates by the first particulate collection filter, collection of particulates by the first particulate collection filter and the second particulate collection filter, and heating of the second particulate collection filter by the heating member.

Methods and systems are provided for filtering particulate matter in an exhaust passage of an engine system. In one example, a method may include during a cold start condition comprising an engine temperature being less than a threshold engine temperature, directing engine exhaust gas to an exhaust particulate filter, and during a warm engine condition, directing engine exhaust gas to bypass the exhaust particulate filter, wherein the warm engine condition comprises the engine temperature being greater than or equal to the threshold engine temperature and fuel being combusted in the engine. In this way, the exhaust particulate filter may be reliably regenerated during engine shutdown events such as DFSOs while reducing filter degradation, and lowering PM emissions.

An aftertreatment system comprises a SCR system, a first filter, and a second filter disposed downstream of the first filter and a bypass conduit providing a flow path bypassing the second filter. A valve is operatively coupled to the bypass conduit and is moveable between a closed position in which the exhaust gas flows through the second filter, and an open position in which at least a portion of the exhaust gas flows through the bypass conduit. A controller is operatively coupled to the valve configured to adjust the valve based on a first filtration efficiency of the first filter to cause the exhaust gas expelled into the environment from the aftertreatment to have a particulate matter count meeting particulate matter emission standards.

A heater is provided that includes at least one resistive heating element having a material with a non-monotonic resistivity vs. temperature profile and exhibiting a negative dR/dT characteristic over a predetermined operating temperature range along the profile. The heater can include a plurality of circuits disposed in a fluid path to heat fluid flow.

A method for operating a heater system including a resistive heating element having a material with a non-monotonic resistivity vs. temperature profile is provided. The method includes heating the resistive heating element to within a limited temperature range in which the resistive heating element exhibits a negative dR/dT characteristic, operating the resistive heating element within an operating temperature range that at least partially overlaps the limited temperature range, and determining a temperature of the resistive heating element such that the resistive heating element functions as both a heater and a temperature sensor. The resistive heating element can function as a temperature sensor in a temperature range between about 500° C. and about 800° C., and the non-monotonic resistivity vs. temperature profile for the material of the resistive heating element can have a local maximum and a local minimum.

Embodiments described herein methods can be used in particulate filter regeneration, such as particulate filters used for filtering the exhaust of an engine, e.g., a diesel engine. Systems herein can be configured to dispense combustion gas(es) into housing were a particulate filter is contained and to ignite the combustion gases. Methods for conducting a safety verification process of such systems are disclosed, as well as methods for regenerating the filters. Still other embodiments are described.

A heating system includes at least one electric heater disposed within a fluid flow system and a control device that is configured to determine a temperature of the at least one electric heater based on a model, at least one fluid flow system input, and at least one heater input. The at least one heater input includes at least one physical characteristic of the heating system, the at least one physical characteristic includes at least one of a resistance wire diameter, a heater insulation thickness, a heater sheath thickness, a conductivity, a specific heat and density of the material of the heater, an emissivity of the heater and the fluid flow pathway, and combinations thereof. The control device is configured to provide power to the at least one electric heater based on the temperature of the at least one electric heater.