Numerical and Experimental Analysis of a Cold Start System Used in Flex Fuel Engines with Heating of Intake Air and Ethanol

摘要

The use of pure ethanol or the prevailing of it in the mixture with gasoline in flex fuel engines, led to a necessity of an auxiliary system to the cold start and engine functioning. Ethanol chemical properties can be used to explain this necessity. Ethanol has been used in Brazil for more than 30 years and many researches give support to the cold start technologic evolution. The cold start system enables the gasoline introduction into the intake manifold of flex fuel engines, when vehicles are using pure ethanol or a mixture with more ethanol than gasoline. The researches challenge is to find a way to start an engine using ethanol without the use of the cold start system using gasoline. This works presents a numerical analysis of the flow and heat transfer in a cold start system, using computational fluid dynamics. An experimental test bench developed to study a cold start system heating air and ethanol. The objective is to use this system to assure the engine operation at low ambient temperatures. The simulations were validated using the experimental data and results shows the possibility to get a temperature high enough to assure fuel combustion.