Judi Steciak

Dynamometer Testing of an Ethanol-Water Fueled Transit Van

Previous research using catalytic igniters and ethanol water fueled mixtures has shown potential for lowering CO and NO x emissions while increasing engine efficiency over conventional -engine configurations. Catalytic ignition systems allow combustion initiation over a much wider range of stoichiometry and water composition than traditional spark ignition systems. The platform explored in this research is a transit van converted to operate on either gasoline or ethanol water fuel mixtures. Special attention was devoted to improve cold starting and installing additional on board sensors and equipment for future testing. System features include integration of a wide band oxygen sensor, state-of-the-art engine management system, exhaust gas temperature sampling using platinum thin film resistive temperature devices and variable voltage control of catalytic igniters using DC-DC boost converters. The platform explored in this research is a transit van converted to operate on either gasoline or ethanol water fuel mixtures. Special attention was devoted to improve cold starting and installing additional on board sensors and equipment for future testing. System features include integration of a wide band oxygen sensor, state-of-the-art engine management system, exhaust gas temperature sampling using platinum thin film resistive temperature devices, and variable voltage control of catalytic igniters using DC-DC boost converters. Extensive engine performance and emissions testing for 70% ethanol 30% water fuel mixtures operating at air to fuel ratios (AFR) of = 1 and = 1.15 have shown a substantial reduction in NOx and CO emissions without the use of exhaust after treatment compared to gasoline emissions. Lean mixtures also show reduced emissions and increased thermal efficiency compared to stoichiometric conditions. Chassis dynamometer tests comparing thermal efficiency, and brake specific emissions of NOx, CO 2 , CO, and hydrocarbons for the ethanol-water fuel mixtures over a wide range of operating conditions are shown.

Catalytic Igniter to Support Combustion of Ethanol-Water/Air Mixtures in Internal Combustion Engines

Lean ethanol-water/air mixtures have potential for reducing NOx and CO emissions in internal combustion engines. Igniting such mixtures is not possible with conventional ignition sources. An improved catalytic ignition source is being developed to aid in the combustion of aqueous ethanol. The operating principle is homogeneous charge compression ignition in a catalytic pre-chamber, followed by torch ignition of the main chamber. In this system, ignition timing can be adjusted by changing the length of the catalytic core element, the length of the pre-chamber, the diameter of the pre-chamber, and the electrical power supplied to the catalytic core element. A multi-zone energy balance model has been developed to understand ignition timing of ethanol-water mixtures. Model predictions agree with pressure versus crank angle data obtained from a 15 kW Yanmar diesel engine converted for catalytic operation on ethanolwater fuel. Comparing the converted Yanmar to the stock engine shows an increase in torque and power, with improvements in CO and NOx emissions. Hydrocarbon emissions increased significantly, but are largely due to piston geometry not well suited for homogeneous charge combustion. Future engine modifications have the potential to lower emissions to current emission standards, without requiring external emission control devices.

Development of a micro-nozzle and ion mobility spectrometer in LTCC

Multilayer ceramic packaging materials provide a versatile platform to fabricate a wide variety of devices from sensors to micro-nozzles. Our research is focused on developing robust sensors for underground deployment and monopropellant micro nozzles for satellite attitude adjustment applications. An LTCC monopropellant micro-nozzle is being developed and tested to provide small thrust vectors for satellite attitude adjustments. High purity hydrogen peroxide undergoes a strong exothermic decomposition reaction in the presence of a silver catalyst. A micro-nozzle and catalyst chamber has been designed to convert hydrogen peroxide liquid to functional thrust. The device uses internal fluidic channels to direct the propellant to a silver lined catalyst chamber. The catalyst decomposes the propellant into water vapor and oxygen at temperatures near 1029 K. The hot gases are then expelled through a contoured nozzle to provide thrust. Complex internal geometric features are created using a CNC milling machine. An ion mobility spectrometer (IMS) is being developed for permanent deployment below ground to continuously analyze groundwater pollutants. Each segment was constructed of multiple layers of green tape. Five Kovar inserts were embedded in the device to function as ion gates. Reduction in size, hermeticity and system integration was made possible by the novel use of LTCC packaging technology.

Catalytic Ignition of Ethanol-Oxygen-Nitrogen Mixtures Over 90% Platinum - 10% Rhodium in Comparison With Pure Platinum

Prior research of the catalytic ignition of renewable transportation fuels was conducted with pure platinum (Pt), an oxidation catalyst with mechanical properties that change at the temperatures expected in internal combustion engines. This study was undertaken to compare and contrast the ability of grain-hardened 90% platinum - 10% rhodium (Pt-Rh) to serve as an ignition catalyst. The temperature required to initiate surface reactions and the rate of heat generated from the reactions of ethanol-oxygen-nitrogen mixtures on Pt-Rh and Pt were obtained using a microcalorimeter. Catalyst wires were exposed to reacting flows in a plug-flow reactor and heated though electrical resistance until surface reactions occurred. The process was repeated for fixed fuel molar percentages of ethanol ranging from 1% to 3% and fuel-oxygen equivalence ratios (Φ) ranging from 0.2 to 1.0 at a constant total volumetric flow rate of 5 L/min, thus testing the effect of both the absolute and relative fuel content. Because of its lower coefficient of thermal resistance, Pt-Rh initiated surface reactions in fuel-oxygen mixtures at temperatures about 45 K higher than pure Pt; 3% ethanol mixtures ignited at an average ignition temperature of 512 K on Pt-Rh with very little variation with Φ while those on Pt ignited at temperatures ranging from a low of 450 K (Φ = 0.5) to a high of 473 K (Φ = 1.0), suggesting fuel-first coverage of the surface for these conditions. Also at 3% ethanol, reactions on Pt-Rh generated heat at an average rate of 5.5 W/cm2 while those on pure Pt generated 19.6 W/cm2 . Pt-Rh did not exhibit significant seasoning at the conditions tested whereas Pt seasoned over time and became more reactive (initiating surface reactions at lower temperatures than an unseasoned surface), a phenomenon observed in prior research. This data will aid in the design and understanding of catalytic igniters used with alternative transportation fuels in internal combustion engines.Copyright

Measuring Ignition Temperature and Heat Generation From Moist Propane-Oxygen Mixtures on Platinum

The surface temperature and heat generation from reactions of propane-water-oxygen-nitrogen mixtures on a platinum wire catalyst were determined using microcalorimetry. A 127 micron diameter, 99.95% pure Pt coiled wire was placed crosswise in the quartz tube of a plug flow reactor. A precision sourcemeter with a four-lead technique allowed the platinum wire to measure its average temperature by serving as a resistance thermometer, and enabled us to determine the amount of heat generated from surface reactions. Ignition temperatures varied from 450 to 500 K and heat generation from 0.8 to 11.5 W/cm2 depending on the absolute amounts of propane and oxygen, the propane:water ratio, and the fuel-oxygen equivalence ratio. As propane:water molar ratios reached 70:30, the temperature required to initiate surface reactions was as much as 6K higher. No clear effect of water addition on the release of energy due to surface reactions was observed; values were within 2% to 3% agreement between wet and dry experiments. These experimental results aid in understanding the heat transfer processes of catalytic igniters used to ignite fuel-lean mixtures.Copyright

Homogeneous Charge Catalytic Ignition of Ethanol-Water/Air Mixtures in a Reciprocating Engine

Lean ethanol-water/air mixtures have potential for reducing NOx and CO emissions in internal combustion engines, with little well-to-wheels CO2 emissions. Conventional ignition systems have been unsuccessful at igniting such mixtures. An alternative catalytic ignition source is being developed to aid in the combustion of aqueous ethanol. The operating principle is homogeneous charge compression ignition inside a catalytic pre-chamber, which causes torch ignition and flame propagation in the combustion chamber. Ignition timing can be adjusted by changing the length of the catalytic core element, the length of the pre-chamber, the diameter of the pre-chamber, and the electrical power supplied to the catalytic core element. To study engine operation, a 1.0L 3-cylinder Yanmar diesel engine was converted for ethanol-water use, and compared with an unmodified engine. Comparing the converted Yanmar to the stock engine shows an increase in torque and power, with improvements in CO and NOx emissions. Hydrocarbon emissions from the converted engine increased significantly, but are largely due to piston geometry not well suited for homogeneous charge combustion. No exhaust after treatment was performed on either engine configuration. Applying this technology in an engine with a combustion chamber and piston design suited for homogeneous mixtures has the potential to lower emissions to current standards, with a simple reduction catalytic converter.

Catalytic Ignition Properties and Surface Reaction Kinetics Modeling From Methane in Oxygen-Nitrogen Mixtures on Platinum

The ignition temperature and heat generation from oxidation of methane on a platinum catalyst were determined experimentally. A 127 micron diameter platinum coiled wire was placed crosswise in a quartz tube of a plug flow reactor. A source meter with a 4-wire measurement capability measured the resistance and current to calculate the average temperature of the surface reaction. Light-off temperatures varied from 730–780K for methane for a fuel-oxygen equivalence ratio of 0.3 to 1.0 at fuel percentages of 2–5% by volume. A model of the experimental system was created using Fluent coupled with Chemkin to combine an advanced chemistry solver with flow simulation. The experimental data was compared to the model results, which includes heat transfer and the surface reaction kinetics of methane on platinum. The heat transfer model obtained values within 4 Kelvin to experimental data for temperatures between 400K and 700K. At temperatures greater than 700K the model deviated with temperatures greater than the experimental by up to 60 Kelvin.Copyright

Design of a Low Cost, Partial Flow Dilution Tunnel With Tapered Element Oscillating Microbalance Particulate Measurement

Accurate, repeatable measurement of tailpipe emissions is an important factor in the development of internal combustion engines and testing of alternative fuels. A dilution tunnel simulates the action of exhaust mixing with atmospheric gases and prevents condensation prior to gas and particulate measurements. In this work, a micro dilution tunnel was designed for the University of Idaho Small Engine Laboratory (SEL), and experiments were conducted to establish the controllability and accuracy of the tunnel. The tunnel design implements partial flow, Constant Volume Sampling (CVS) using an ejector diluter. Real-time measurement of CO2, CO, O2, NOx, hydrocarbons, and particulate emissions are collected using the combination of a NDIR/electrochemical 5-gas analyzer and a Tapered Element Oscillating Microbalance (TEOM). Data from these instruments and the flow conditioning equipment are collected and logged by a National Instruments data acquisition system. For the desired 11:1 dilution ratio, the system should be operated at 700°F suction temperature and 35 psia motive pressure. This results in an uncertainty of 3% at the 80% confidence level. A procedure has been developed for obtaining and verifying dilution ratios between 11:1 and 15:1. The characterization and use of an ejector diluter have made it possible to create an inexpensive dilution tunnel that will be useful in studying effects of freezing chemical reactions, and analyzing emissions of diesel and two-stroke engines that typically produce elevated levels of hydrocarbons and particulates beyond the saturation range of many emissions analyzers.Copyright

Measuring Ignition Temperature and the Rate of Energy Generation From Canola Methyl Ester and Soy Methyl Ester in Oxygen-Nitrogen Mixtures on Platinum-Rhodium

A heated plug flow reactor was used to study the reactions of nonflammable mixtures of canola methyl ester-oxygen and soybean methyl ester-oxygen diluted with nitrogen over a coiled 90%:10% platinum:rhodium wire catalyst. The temperature the catalyst needed to reach to initiate surface reactions (ignition temperature) and the subsequent rate of energy generation were determined. The absolute volume fraction of fuel was varied from 0.238% to 0.445% and the relative fuel-oxygen equivalence ratio, φ, was varied between 0.4 and 1.0. The 127 micrometer diameter Pt-Rh wire was coiled and suspended crosswise in the quartz tube of the reactor. Evaporated biodiesel was delivered by heated nitrogen into the apparatus and blended with oxygen in a mixing nozzle. The wire catalyst was electrically heated and acted as a resistance thermometer to measure its average temperature. Ignition temperatures increased with increasing equivalence ratio and volumetric fuel vapor percentage, thus indicating initial fuel coverage of the catalyst surface. Temperatures as low as 912 K at φ = 0.4 for 0.268% Soy Methyl Ester (SME) and as high as 991 K at φ = 1.0 for 0.445% Canola Methyl Ester (CME) were recorded. The rate of energy generated due to surface reactions for both biodiesels decreased with increasing equivalence ratio and generated less energy as fuel percentages decreased. The lowest and highest rates of energy generation were both obtained from experiments with CME with 6.9 W/cm2 at φ = 1 for 0.268% fuel and 25.3 W/cm2 at φ = 0.4 for 0.445% fuel. The extremes of the rate of heat generated from SME reactions were 5.1 W/cm2 and 28.6 W/cm2 , both at φ = 0.4, with 0.238% and 0.417% fuel, respectively. Another outcome of this work was achieving steady evaporation of microliter/hour heavy fuel vapor flow rates. This was aided by thermogravimetric analysis (TGA) to determine thin-film vaporization temperatures. CME and SME had the lowest evaporation temperatures of 188 K and 186 K, respectively.Copyright

Measuring and Comparing Accuracy of Emissions Analyzers for Use With IC Engines

Automotive emission analyzers vary in price from under