A system is provided. The system includes a controller communicatively coupled to an industrial combustion engine and an exhaust gas recirculation (EGR) system, wherein the EGR system is configured to route exhaust gas generated by the industrial combustion engine from at least one exhaust system to at least one intake system, the EGR system includes multiple EGR circuits, each EGR circuit of the multiple EGR circuits includes an EGR cooler unit including at least two of a high temperature non-condensing cooler, a low temperature condensing cooler, an adiabatic gas/liquid separator, and a reheater. The controller includes a processor and a non-transitory memory encoding one or more processor-executable routines, wherein the one or more routines, when executed by the processor, cause the controller to control operations of both the industrial combustion engine and the EGR system.

Methods and systems are provided for merging recirculated exhaust gas (EGR) with fresh intake air in an intake passage. In one example, a method may include introducing EGR to the intake passage via an angled annular slot and flowing unmixed EGR and ambient air through an intake compressor inlet. Ambient air may flow to a center of the intake compressor while the EGR may flow along a periphery of the intake compressor inlet.

An EGR estimation method for estimating an EGR rate in an intake and exhaust system of an internal combustion engine, the intake and exhaust system including: an intake system including an air cleaner and an intake passage that connects the air cleaner and the engine, an exhaust system including an exhaust passage, and a supercharger that is provided in the intake passage and the exhaust passage, the intake and exhaust system including an EGR device including an EGR passage that connects the intake passage and the exhaust passage and an EGR valve, and the intake system including an intake bypass passage that connects an upstream pressure portion and a downstream pressure portion of the supercharger and a recirculation valve. The EGR estimation method includes: opening the recirculation valve during supercharging, and estimating the EGR rate after closing the EGR valve based on the EGR rate before opening the recirculation valve.

An EGR estimation method for estimating an EGR rate in an intake and exhaust system of an internal combustion engine, the intake and exhaust system including: an intake system including an air cleaner and an intake passage that connects the air cleaner and the engine, an exhaust system including an exhaust passage, and a supercharger that is provided in the intake passage and the exhaust passage, the intake and exhaust system including an EGR device including an EGR passage that connects the intake passage and the exhaust passage and an EGR valve, and the intake system including an intake bypass passage that connects an upstream pressure portion and a downstream pressure portion of the supercharger and a recirculation valve. The EGR estimation method includes: opening the recirculation valve during supercharging, and estimating the EGR rate after closing the EGR valve based on the EGR rate before opening the recirculation valve.

An EGR estimation method for an internal combustion engine 1 estimates an EGR rate in an intake and exhaust system 10, 20 of an internal combustion engine, the intake and exhaust system 10, 20 of an internal combustion engine including an intake system 10, an exhaust system 20, and an EGR device 40, the EGR device 40 includes an EGR passage 41 and an EGR valve 43. The EGR estimation method includes determining a gas replacement state by exhaust gas and fresh air in an upstream EGR passage, which is a portion of the EGR passage between the EGR valve and the exhaust passage, when fuel cut of the internal combustion engine is started and the EGR valve is fully closed; and estimating the EGR rate based on a result of the determination.

An embodiment apparatus for reducing fouling of an exhaust gas recirculation (EGR) cooler includes an exhaust gas transfer part configured to connect a diesel oxidation catalyst (DOC) of an exhaust gas post-treatment system extending from an engine through an exhaust line to an EGR cooler installed in an EGR line and configured to recirculate exhaust gas discharged from an exhaust manifold to an intake manifold, a valve installed in the exhaust gas transfer part, and a controller configured to selectively open the valve as the exhaust gas post-treatment system enters a predetermined diesel particulate filter (DPF) regeneration condition and allow exhaust gas discharged from the DOC to be supplied to the EGR cooler through the exhaust gas transfer part.

The subject matter of this specification can be embodied in, among other things, a gas mixer that includes a convergent-divergent nozzle comprising a convergent portion and a divergent portion and defining a first gas flow path, an air housing comprising an air inlet configured to supply air to the first gas flow path upstream of the convergent-divergent nozzle, a gas housing defining a second gas flow path and including a first gas inlet configured to receive a secondary gas and allow the secondary gas into a second gas flow path, and a gas nozzle positioned parallel to and centrally within the first gas flow path in a convergent portion of the convergent-divergent nozzle, the gas nozzle configured to supply the secondary gas to the first gas flow path upstream of the divergent portion.

The subject matter of this specification can be embodied in, among other things, a gas mixer that includes a convergent-divergent nozzle comprising a convergent portion and a divergent portion and defining a first gas flow path, an air housing comprising an air inlet configured to supply air to the first gas flow path upstream of the convergent-divergent nozzle, a gas housing defining a second gas flow path and including a first gas inlet configured to receive a secondary gas and allow the secondary gas into a second gas flow path, and a gas nozzle positioned parallel to and centrally within the first gas flow path in a convergent portion of the convergent-divergent nozzle, the gas nozzle configured to supply the secondary gas to the first gas flow path upstream of the divergent portion.

Disclosed are two system devices for stratified injecting the recirculated exhaust gas and high-specific-heat-capacity or inert gas for clean combustion of an internal combustion engine. The former is composed of an exhaust gas recirculation system, an injection system, and a power system. The latter is composed of four parts, and a high-specific-heat-capacity gas or inert gas channel is added. Injectors can be arranged at any position in the cylinder between a top dead center and a bottom dead center of a piston in a cylinder; 1-3 layers of injectors can be arranged; and 2-6 injectors can be arranged on each layer. Gas participating in combustion enters the cylinder from two intake channels, namely, a scavenging port of the internal combustion engine and the injectors; an in-cylinder swirl ratio can be remarkably increased through kinetic energy carried by the gas; and fuel-gas mixing is promoted, and the combustion rate is increased.

A control apparatus for an engine is provided. The control apparatus includes an intake control valve controller for fully closing, when an engine stop request is issued, an intake control valve for adjusting a flow rate of intake air passing through an intake passage of the engine, an engine speed increase controller for increasing an engine speed to reach a target speed after the intake control valve is fully closed by the intake control valve controller, and a fuel injection stopper for stopping a fuel injection after the engine speed is increased by the engine speed increase controller.