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EXTERNAL MIXTURE FORMATION FOR HOMOGENOUS CHARGE COMPRESSION IGNITION

IP.com Disclosure Number: IPCOM000192565D
Publication Date: 2010-Jan-25
Document File: 7 page(s) / 46K

Publishing Venue

The IP.com Prior Art Database

Abstract

The present invention discloses a technique that enables a fuel injection for a premixed combustion of diesel (homogenous charge compression Ignition or HCCI). Further, the present technique minimizes emissions of diesel reciprocating engines without using a particle filter and NOx after treatment. The technique increases the power density of the engine and avoids pre-ignition compared to air-preheating concepts. Moreover, the technique is also able to be combined for a partially premixed operation with a direct diesel injection.

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RP13289

EXTERNAL MIXTURE FORMATION FOR HOMOGENOUS CHARGE COMPRESSION IGNITION

BRIEF ABSTRACT

    The present invention discloses a technique that enables a fuel injection for a premixed combustion of diesel (homogenous charge compression Ignition or HCCI). Further, the present technique minimizes emissions of diesel reciprocating engines without using a particle filter and NOx after treatment. The technique increases the power density of the engine and avoids pre-ignition compared to air-preheating concepts. Moreover, the technique is also able to be combined for a partially premixed operation with a direct diesel injection.

KEYWORDS

    Fuel injection, diesel reciprocating engine(s), power density, pre-ignition, air-preheating, partially premixed operation, combustion of diesel, homogenous charge compression Ignition, wall film, wall wetting, induced swirl, engine efficiency, power density

DETAILED DESCRIPTION

    Homogeneous charge compression ignition (HCCI) is a form of internal combustion in which well-mixed fuel and oxidizer (typically air) are compressed to the point of auto-ignition. As in other forms of combustion, this exothermic reaction releases chemical energy into a sensible form that can be translated by an engine into work and heat.

    The homogenous charge compression ignition requires a premixing of a fuel and air before the combustion which is a challenge especially with the diesel

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RP13289

fuels. While, compared with other fuels, diesel fuel ignites fast at low temperatures and evaporates at high temperatures. Concepts with external mixture formation, therefore typically lead to high wall wetting with the fuel or the charge air has to be preheated significantly leading to pre-ignition and power reduction. This wall wetting may cause very high HC (hydro carbon) and CO (carbon monoxide) emissions and in homogeneities in the cylinder reduce the benefit of the premixed operation significantly.

    Conventional diesel reciprocating engines inject the fuel close to TDC (top dead center) into the compressed air leading to ignition before the fuel is completely premixed with air. This leads to high temperature diffusion combustion with high NOx and soot formation. But by premixing the fuel with air before the combustion and keeping the flame temperatures low, NOx and soot emissions can be reduced significantly. The premixing is an essential element to reduce the in-cylinder soot formation in addition to the NOx emissions. A high degree of homogeneity can be achieved with an external mixture formation (port injection).

    Unfortunately the external premixing of diesel with air leads to the various issues or problems. Deposits of diesel at the walls (wall wetting) and quenching typically lead to a reduced combustion efficiency and high HC and CO emissions. To reduce this issue, diesel concepts have been propose...