Recently, industry and government have joined together to develop high efficiency, low emissions, natural gas fueled, industrial, reciprocating engines for power generation. The California Energy Commission targets fuel-to-electricity efficiency at over 50% and NOx less than 0.01 gm/BHP-hr by the year 2010 [1]. The Department of Energy’s ARES program has targeted 50% efficiency and 0.1 gm/BHP-hr NOx by 2010 [2]. The engine manufacturers have determined that these goals cannot be met with current ignition system technology. They have jointly developed a specification for the next generation ignition system [3], which will support meeting the engine cost, efficiency and emissions goals. The Electrically Controlled Combustion Optimization System (ECCOS) is a new technology (patent pending) which is designed to meet or exceed this specification. This ignition system generates a high voltage, low current, radio frequency electrostatic field inside the combustion chamber to efficiently ionize the air and fuel mixture and initiate multiple flame fronts. The system is able to reliably introduce much higher ionization energy to the combustion chamber than conventional ignition systems because the ionization is done with a high voltage electric field, not high temperature. Conventional ignition systems generate up to 30,000 deg F of temperature in the spark plug gap. This temperature is created in the plug gap by a high current, low voltage plasma arc. The reliance of the conventional ignition system on temperature to initiate combustion limits the maximum energy that can be delivered because the high temperatures erode the electrodes. Since the ECCOS does not generate these high temperatures, electrode erosion should not be a problem. This paper presents a comparison of combustion characteristics between a conventional ignition system and the ECCOS igniting various mixture rations of propane and air in a constant volume combustion test chamber. Pressure rise rates as well as combustion photographs of the ignition and flame propagation processes are presented. In addition, experimental data obtained from the natural gas, single-cylinder engine operating with a conventional ignition system and the ECCOS are presented. Combustion rates, ignition delay, fuel consumption and emissions are presented at various air-fuel ratios.

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