SAE International Heated Injectors for Ethanol Cold Starts 2009-01-0615

Ethanol is commonly employed as a transportation fuel in Brazil. However, since pure ethanol's flash point is 12°C, flex-fuel vehicles marketed in Brazil are currently equipped with a redundant fuel system which delivers gasoline during cold starts below [typically] 18°C. Since these low temperatures are infrequently experienced in Brazil, gasoline in the auxiliary fuel tank may evaporate and/or varnish during extended dormant periods, resulting in poor quality or no-starts. It is therefore desirable to eliminate the gasoline system by vaporizing a sufficient quantity of ethanol to enable cold starts at low ambient temperatures. A port fuel injector capable of rapidly heating ethanol above its flash point has been developed which eliminates the need for the redundant fuel system. During cold-start conditions, the vehicle's controller commands power to an electrical heater contained within each injector. The injector heaters raise the temperature of the delivered ethanol during the engine crank and initial run. When these heated injectors are employed in conjunction with engine management system enhancements, ethanol cold start performance is similar to that of gasoline. In addition, heating ethanol fuel enables the leaning-out of 20°C cold start fueling, which has shown to reduce both engine-out and FTP bag emissions. Heated injector flow temperature data, low ambient temperature engine cold start performance and vehicle FTP emission results are presented and discussed.