Secondary air injection

About: Secondary air injection is a research topic. Over the lifetime, 11452 publications have been published within this topic receiving 112147 citations.

Series combination catalytic converter

Abstract: The present invention is particularly applicable to lean burn engines that produce exhaust containing insufficient amounts of unburned hydrocarbons to satisfactorily reduce NOx emissions without undermining engine performance. In the exhaust purification system, ethanol or another suitable hydrocarbon is injected into the exhaust stream at an appropriate location between the engine and the catalytic converter. A deNOx catalytic converter is positioned within the exhaust downstream from the ethanol injection point. The combination engine application, ethanol injection and suitable deNOx catalyst combine to reduce NOx to satisfactory levels without producing significant amounts of undesirable secondary nitrogen containing compounds. An oxidation catalytic converter is positioned in the exhaust downstream from the deNOx catalytic converter. The oxidation catalyst serves to convert any remaining unburned hydrocarbons into carbon dioxide and water. At the same time, only small amounts of secondary nitrogen compounds are converted back into NOx compounds upon passage through the oxidation catalyst. The end result being an over all reduction in both HC and NOx compounds particularly for lean burn engines to satisfactory levels.

Process for cooling diesel engine exhaust gases

Abstract: A process and a suitable arrangement for cooling diesel engine exhaust gases in an exhaust gas recirculation system is provided. In order to be able to avoid a contamination of the heat exchanger as well as a resulting required regenerating of the latter in the case of a cooling of the hot exhaust gas flow over a large temperature range, the cooling of the hot exhaust gas flow is carried out in at least two steps in that the exhaust gas flow flows successively through two heat exchangers which are each adapted to the corresponding cooling temperature range. By adapting the heat exchangers to specific small temperature ranges, even hot exhaust gas flows of up to 800° C. can be cooled to a desired low temperature by the series connection of a corresponding number of different heat exchangers, without causing significant contaminations of the exhaust gas cooling arrangement by exhaust gas particles. By the use of known heat exchangers, the construction of the exhaust gas cooling system becomes particularly reasonable with respect to cost.

Characteristics of low temperature and low oxygen diesel combustion with ultra-high exhaust gas recirculation:

Abstract: Ultra-low NOx and smokeless operation at higher loads up to half of the rated torque is attempted with large rates of cold exhaust gas recirculation (EGR). NOx decreases below 6 ppm (0.05 g/kW h) and soot significantly increases when first decreasing the oxygen concentration to 16 per cent with cold EGR. However, after peaking at 12–14 per cent oxygen, soot then decreases sharply to essentially zero at 9–10 per cent oxygen while maintaining ultra-low NOx, regardless of fuel injection quantity and injection pressure. However, at higher loads, with the oxygen concentration below 9–10 per cent, the air-fuel ratio has to be over-rich to exceed half of the rated torque, and thermal efficiency, CO, and THC deteriorate significantly. As the EGR rate increases, exhaust gas emissions and thermal efficiency vary with the intake oxygen content rather than with the excess air ratio. Longer ignition delays due to either advancing or retarding the injection timing reduced the smoke emissions, but advancing the ...

Air-compressing fuel-injection internal-combustion engine with an exhaust treatment device for reduction of nitrogen oxides

Abstract: The invention relates to a diesel internal combustion engine with an exhaust treatment device for the reduction of nitrogen oxides and with a fuel injection system comprising a high-pressure pump and at least one solenoid valve-controlled injection nozzle. The injection nozzle is actuated by an electronic control unit and is intended both for the primary injection, provided for the combustion, and for the additional injection, influencing the effectiveness of the exhaust treatment device. The fuel injection nozzle provided for the primary injection also provides for the secondary injection. The secondary injection takes place as a supplementary injection at the earliest in the region of the end phase of the combustion after the ignition top dead center.