Analysis of the Physical Boundary Conditions for the Layout of an Optimized Ethanol Low-Temperature Mixture Preparation Device 2009-01-0618

The paper presents the basic scientific analytical approach to identify the main physical parameters, which enable an optimization of several layouts for an Ethanol Cold Start (ECS) device. The main optimization criteria for the system layout are a single mixture preparation system for both cold start and hot engine handling, a short energy release time, a short start time and a possible high-precision ethanol metering system capability after start. The paper describes 3 suggested solutions. Two of the solutions are prototyped and tested on several vehicles. The paper concludes with a series of experimental data obtained on different flex engines with the new ECS-system variants. The obtained test results show good pure ethanol cold start capability for temperatures above 263 K and an excellent system temperature control of the fuel in the fuel-rail and in the injectors, which prevents the occurrence of any cavitations phenomenon. The excellent temperature control enables the use of the ECS-system during the warm up period for improvement of vehicle drivability and for reduction of the HC-emissions during the first part of the FTP-cycle.