HEAT PIPE FOR USING EXHAUST HEAT TO IMPROVE MIXTURE FORMATION IN DIESEL ENGINES (18-Jan-2010)

RP13280

HEAT PIPE FOR USING EXHAUST HEAT TO IMPROVE MIXTURE FORMATION IN DIESEL ENGINES

BRIEF ABSTRACT

    A technique for improving mixture formation in diesel engines is disclosed. The proposed technique utilizes a heat pipe to leverage exhaust heat for fuel preheating and/or evaporation. Preheating or evaporating liquid fuel improves the mixture formation, thereby reducing Nox and soot levels in exhaust emissions from the diesel engines.

KEYWORDS

    NOx, soot, emission, exhaust gas, exhaust heat, heat pipe, evaporation, liquid fuel, preheating, mixture, diesel engine, combustion efficiency, fuel injection, homogeneous combustion, heat flux, latent heat

DETAILED DESCRIPTION

    Diesel engines have long served the transportation industry, delivering power with excellent fuel economy. Though polluting particles and gases emitted from the diesel engines remains a concern. Further, current and upcoming air quality regulations require drastic cuts in NOx and soot emissions from such diesel engines.

         Generally, various techniques have been employed and researched for reducing the Nox and the soot levels in diesel engine emissions. Among all such techniques, after treatment techniques provide the best results and allow compliance with the stringent emission level regulations. The after treatment

1

RP13280

techniques include Selective Catalytic Reduction techniques to reduce the Nox levels and have particle filter to filter out the soot particles from the exhaust.

         One reason for high NOx and soot levels in the exhaust from the diesel engines is the deterioration of combustion efficiency that accompanies stoichiometric diesel combustion due to poor mixing. One technique employed to improve mixture formation and to achieve more homogenous combustion is combustion with flash injection using electric pre-heating of the fuel . Another technique employed to improve the degree of premixing is evaporation of the fuel with electric heating and port injection for a homogenous combustion. Yet another technique employed is timed port Injection for external mixture formation with diesel. However, such conventional techniques suffer from limited degree of premixing and/or wall wetting in the port with the corresponding problems. Therefore, there is a need in the art for a technique that improves the mixture formation to increase the degree of mixing and reduces soot and NOx emissions in the exhaust.

         The present invention discloses a technique that uses exhaust heat to improve mixture formation in the diesel engines. Liquid fuel is preheated and/or evaporated with exhaust heat before injecting and mixing with air. A heat pipe is used to transfer the exhaust heat from the exhaust duct to a location where the liquid fuel is preheated and/or evaporated.

         The heat pipe allows very high heat fluxes with defined temperatures at the exhaust...