Jess W. Gingrich

Cooled exhaust-gas recirculation for fuel economy and emissions improvement in gasoline engines:

Modern gasoline engines face fuel-efficiency challenges due to inherent limitations including knock, pumping losses, and fuel enrichment. The addition of exhaust-gas recirculation (EGR) has been shown to improve the fuel consumption of gasoline engines, either port fuel injected or direct injected, by reducing pumping losses and knock and eliminating the enrichment region. In addition, the use of EGR has been shown to substantially reduce emissions of nitrogen oxides (NO x ) and CO. A 2.4-litre multi-point injection engine and a 1.6-litre gasoline direct injection engine were run with high levels of both cooled and uncooled EGR. Unlike numerous previous publications, these engines included a modified ignition system that allows extension of the cooled EGR limit of the engine to greater than 25 per cent and improves combustion at lower EGR levels. The results showed that an improvement of between 5 and 30 per cent in fuel consumption is possible, with the largest improvement occurring in the typical enrichment region. In addition, the results showed that EGR can reduce knock, resulting in an improvement in combustion phasing. Finally, the high levels of EGR reduced the emissions of CO by 30 per cent and of NO x by up to 80 per cent. A detailed effort has been made to quantify the sources of improvement throughout the engine cycle and to demonstrate an EGR strategy (cooled EGR at high loads, internal EGR at low loads) that will maximize fuel consumption improvements. The results presented here indicate that the use of EGR in gasoline engines has the potential to reduce fuel consumption and emissions in a very cost-effective manner.

Development of Advanced Laser Ignition System for Stationary Natural Gas Reciprocating Engines

Laser ignition is considered the prime alternative to conventional coil based ignition for improving efficiency and simultaneously reducing NOx emissions in lean-burn natural gas fired stationary reciprocating engines. In this paper, Argonne’s efforts towards the development of a viable laser ignition system are presented. The relative merits of various implementation strategies for laser based ignition are discussed. Finally, the performance improvements required for some of the components for successful field implementation are listed. Also reported are efforts to determine the relative merit of laser ignition over conventional Capacitance Discharge Ignition (CDI) ignition. Emissions and performance data of a large-bore single cylinder research engine are compared while running with laser ignition and the industry standard CDI system. It was primarily noticed that NOx emissions reduce by 50% under full load conditions with up to 65% reductions noticed under part load conditions. Also, the lean ignition limit was significantly extended and laser ignition improved combustion stability under all operating conditions. Other noticeable differences in combustion characteristics are also presented. Efforts wherein ignition was achieved while transmitting the high-power laser pulses through optical fibers showed performance improvements similar those achieved by using free-space laser ignition.© 2005 ASME

Ethanol Flex-fuel Engine Improvements with Exhaust Gas Recirculation and Hydrogen Enrichment

An investigation was performed to identify the benefits of cooled exhaust gas recirculation (EGR) when applied to a potential ethanol flexible fuelled vehicle (eFFV) engine. The fuels investigated in this study represented the range a flex-fuel engine may be exposed to in the United States; from 85% ethanol/gasoline blend (E85) to regular gasoline. The test engine was a 2.0-L in-line 4 cylinder that was turbocharged and port fuel injected (PFI). Ethanol blended fuels, including E85, have a higher octane rating and produce lower exhaust temperatures compared to gasoline. EGR has also been shown to decrease engine knock tendency and decrease exhaust temperatures. A natural progression was to take advantage of the superior combustion characteristics of E85 (i.e. increase compression ratio), and then employ EGR to maintain performance with gasoline. When EGR alone could not provide the necessary knock margin, hydrogen (H2) was added to simulate an onboard fuel reformer. This investigation explored such a strategy at full load, and examined the potential of EGR for ethanol blends at part and full load. This investigation found the base engine torque curve could be matched across the range of fuels at a higher compression ratio. The engine could operate at maximum brake torque (MBT) timing at full load for all but the lowest octane fuel. Fuel enrichment was not needed to control exhaust temperatures, whereby carbon monoxide emissions were drastically reduced. Full load fuel consumption was reduced by 8-10% with regular gasoline (92 RON) and 20-21% with premium (100 RON). Full load brake thermal efficiency (BTE) increased 9.3 percentage points with E85 compared to the base engine. The full load fuel consumption was only 9% higher than the baseline engine even though E85 has ~25% lower energy content (net heat of combustion) than gasoline.

Combustion Characteristics and Engine Performance of a New Radio Frequency Electrostatic Ignition System Igniting Lean Air-Fuel Mixtures

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.Copyright