Rich Combustor Device for Cold Starting Alcohol Fueled Engines:
Irick, David K

     Abstract: Alcohol, (methanol and ethanol) have been identified as having the potential to improve air quality when used to replace conventional gasoline. This potential is primarily due to the different organic species that are emitted by the alcohol-fueled engines. The use of "near neat" alcohol gives greater benefits than fuels containing fuels with lower levels of alcohol, but neat alcohol present a significant cold starting problem.

     The prime objective of this study was to develop a rich combustor device, which will extend the cold starting range of alcohol, fueled engines to –30⁰C while reducing cold starting emissions. In support of this objective a software model was developed which includes the thermodynamic operation of the device as part of a vehicle, considering engine parameters, vehicle parameters and driving cycle requirements.

     The analytical portion of this project consisted of developing the software model to simulate the operation of the combustor. The model determines the relationship between the combustor inputs (fuel and airflow) and outputs (composition, temperature, and flow rates of the exhaust products). The model predicts the output composition using the shifting equilibrium approach. The model includes engine and vehicle parameter inputs, which will allow the simulation of driving cycle. Chemical kinetics is not considered.

     The experimental portion of this project includes design, fabrication, and testing of the rich combustor devices. The combustor design and installation takes into consideration all the criteria of proper vehicle operation such as requirement for actuating, shutdown, and phase-out of the device at different operating conditions. Design also takes into consideration nozzle selection air and fuel flow regulation, ignition system selection, material type, and fabrication method. The prototype rich combustor was tested extensively to determine its performance. The tests were done over a range of ambient temperatures and included mapping of the following parameters: fuel and air flow, output gas composition and temperature, and combustor temperature (at different locations on the apparatus). Because of the availability of cold temperature testing capabilities, including an engine dynamometer, and an engine identical to the engine in the test vehicle, the task of vehicle integration could be logically be combined, to a great extent, with the testing and development of the prototype. We used the dynamometer driving the engine as a pump to test the combustor while the issues of fit, interfaces, and control were concurrently addressed. With this capability, a parallel approach allowed many of the problems associated with vehicle integration to be addressed early in the development of the combustor.

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Point of Contact: David Irick (phone: 865-974-0863, dki@utk.edu)