Michael D. Kass

Compatibility of elastomers with test fuels of gasoline blended with ethanol

This article summarises the compatibility of six elastomers – used in fuel storage and delivery systems – with test fuels representing gasoline blended with up to 85% ethanol. Individual coupons were exposed to test fuels for four weeks to achieve saturation. The change in volume and hardness, when wetted and after drying, were measured and compared with the original condition.

UTILIZING WATER EMULSIFICATION TO REDUCE NOX AND PARTICULATE EMISSIONS ASSOCIATED WITH BIODIESEL

A key barrier limiting extended utilization of biodiesel is higher NOx emissions compared to petrodiesel fuels. The reason for this effect is unclear, but various researchers have attributed this phenomena to the higher liquid bulk modulus associated with biodiesel and the additional heat released during the breaking of C-C double bonds in the methyl ester groups. In this study, water was incorporated into neat biodiesel (B100) as an emulsion in an attempt to lower NOx and particulate matter (PM) emissions. A biodiesel emulsion containing 10wt% water was formulated and evaluated against an ultra-low-sulfur petroleum diesel (ULSD) and neat biodiesel (B100) in a light-duty diesel engine operated at 1500 rpm and at loads of 68 and 102 Nm (50 and 75 ft-lbs). The influence of exhaust gas recirculation (EGR) was also examined. The incorporation of water was found to significantly lower the NOx emissions of B100 while maintaining fuel efficiency when operating at 0% and 27% EGR; however, NOx emissions were observed to increase slightly for the emulsified fuel when the engine load was raised to 102 Nm (75 ft-lbs). The soot fraction of the particulates (as determined using an opacity meter) was much lower for the B100 and B100-water emulsion compared to the ULSD. In contrast, total PM mass (for the three fuel types) was unchanged for the 0% EGR condition but was significantly lower for the B100 and B100-emulsion during the 27% EGR condition compared to the ULSD. Analysis of the emissions and heat release data indicate that water enhances air-fuel premixing to maintain fuel economy and lower soot formation. The exhaust chemistry of the biodiesel base fuels (B100 and water-emulsified B100) was found to be unique in that they contained measurable levels of methyl alkenoates, which were not found for the ULSD. These compounds were formed by the partial cracking of the methyl ester groups during combustion.

Assessment of Corrosivity Associated With Exhaust Gas Recirculation in a Heavy-Duty Diesel Engine

A high-resolution corrosion probe was placed within the airhorn section of the exhaust gas recirculation (EGR) loop of a heavy-duty diesel engine. The corrosion rate of the mild-steel probe elements was evaluated as a function of fuel sulfur level, EGR fraction, dewpoint margin, and humidity. No significant corrosion was observed while running the engine using a No. 2 grade, < 15ppm sulfur diesel fuel; however, high corrosion rates were observed on the probe elements when operating the engine using a standard grade No. 2 diesel fuel (~350 ppm sulfur) while condensing water in the EGR loop. The rate of corrosion on the mild steel elements was found to increase with increasing levels of sulfate in the condensate. However, the engine conditions influencing the sulfate level were not clearly identified in this study.

Ultrasonically induced fragmentation and strain in alumina particles

High purity alumina particles were sonicated in distilled water at 20 kHz. Ultrasonic fragmentation of the alumina particles produced a fine particle fraction, which was less than 1 μm in diameter. This fraction became more pronounced with increased duration and applied power. Particle fragmentation was observed to increase slightly with large increases in slurry density, indicating that the formation and collapse of cavitation bubbles were relatively unaffected by the particulate loading levels. Of great importance, the sonified powders exhibited an exotherm consistent with lattice strain energy release, thereby potentially providing an additional driving force for densification during sintering.

Selective Catalytic Reduction of NOx Emissions from a 5.9 Liter Diesel Engine Using Ethanol as a Reductant

NOx emissions from a heavy-duty diesel engine were reduced by more than 90% and 80% utilizing a full-scale ethanol-SCR system for space velocities of 21000/h and 57000/h respectively. These results were achieved for catalyst temperatures between 360 and 400°C and for C1:NOx ratios of 4-6. The SCR process appears to rapidly convert ethanol to acetaldehyde, which subsequently slipped past the catalyst at appreciable levels at a space velocity of 57000/h. Ammonia and N 2 O were produced during conversion; the concentrations of each were higher for the low space velocity condition. However, the concentration of N 2 O did not exceed 10 ppm. In contrast to other catalyst technologies, NOx reduction appeared to be enhanced by initial catalyst aging, with the presumed mechanism being sulfate accumulation within the catalyst. A concept for utilizing ethanol (distilled from an E-diesel fuel) as the SCR reductant was demonstrated.

Ultrasonic modification of alumina powder during wet-ball milling☆

The comminution of unagglomerated alumina powders was enhanced by applying ultrasonic energy during wet-ball milling for 16 h. The resulting powders had significantly finer mean and median particle sizes, narrower particle-size distributions, and less angular morphologies than powders which were conventionally wet-ball milled.

Synergies of PCCI-Type Combustion and Lean NOx Trap Catalysis for Diesel Engines

It is widely recognized that future NOx and PM emission targets for diesel engines cannot be met solely via advanced combustion over the full engine drive cycle. Therefore some combination of advanced combustion methodology with an aftertreatment technology will be required. In this study, NOx reduction, fuel efficiency, and regeneration performance of lean NOx trap (LNT) were evaluated for four operating conditions. The combustion approaches included baseline engine operation with and without EGR, two exhaust enrichment methods (post injection and delayed injection), and one advanced combustion mode to enable high efficiency clean combustion (HECC). A 1.7 liter 4-cylinder diesel engine was operated under five conditions, which represent key interest points for light-duty diesel operation. At the low load setting the exhaust temperature was too low to enable LNT regeneration and oxidation; however, HECC (low NOx) was achievable. HECC was also reached under more moderate loads and the exhaust temperatures were high enough to enable even further NOx reductions by the LNT. At high loads HECC becomes difficult but the LNT performance improves and acceptable regeneration can be met with enrichment methodologies.

Lowering NOx and PM Emissions in a Light-Duty Diesel Engine with Biodiesel-Water Emulsions

A key barrier limiting extended utilization of biodiesel is higher NOx emissions compared to petrodiesel fuels. The reason for this effect is unclear, but various researchers have attributed this phenonmena to the higher liquid bulk modulus associated with biodiesel and the additional heat released during the breaking of C-C double bonds in the methyl ester groups. In this study water was incorporated into neat biodiesel (B100) as an emulsion in an attempt to lower NOx and particulate matter (PM) emissions. When added to petroleum diesel, water has been shown to improve fuel/air mixing, reduce peak combustion temperatures, and increase mass during combustion, resulting in lower NOx and PM emissions with no fuel penalty. A biodiesel emulsion containing 10wt% water was formulated and evaluated against an ultra-low sulfur petroleum diesel (ULSD) and neat biodiesel (B100) in a light-duty diesel engine operated at 1500RPM and 50ft-lbs. The influence of exhaust gas recirculation (EGR) was also examined. The incorporation of water was found to significantly lower the NOx emissions while maintaining or improving fuel efficiency when operating at 0 and 27% EGR, while the total PM mass was lowered dramatically for the 27% EGR condition only. Analysis of the emissions and heat release data indicate that water enhances air-fuel premixing to maintain fuel economy and lower PM.

Compatibility Assessment of Elastomer Materials to Test Fuels Representing Gasoline Blends Containing Ethanol and Isobutanol

The compatibility of elastomeric materials used in fuel storage and dispensing applications was determined for test fuels representing neat gasoline and gasoline blends containing 10 and 17 vol.% ethanol, and 16 and 24 vol.% isobutanol. The actual test fuel chemistries were based on the aggressive formulations described in SAE J1681 for oxygenated gasoline. Elastomer specimens of fluorocarbon, fluorosilicone, acrylonitrile rubber (NBR), polyurethane, neoprene, styrene butadiene rubber (SBR) and silicone were exposed to the test fuels for 4 weeks at 60°C. After measuring the wetted volume and hardness, the specimens were dried for 20 hours at 60°C and then remeasured for volume and hardness. Dynamic mechanical analysis (DMA) was also performed to determine the glass transition temperature (T g ). Comparison to the original values showed that all elastomer materials experienced volume expansion and softening when wetted by the test fuels. The fluorocarbons underwent the least amount of swelling ( 100%). The level of swelling for each elastomer was higher for the test fuels containing the alcohol additions. In general, ethanol produced slightly higher swell than the oxygen equivalent level of isobutanol. When dried, the fluorocarbon specimens were slightly swollen (relative to the baseline values) due to fuel retention. The NBRs and neoprene exhibited shrinkage and embrittlement associated with the extraction of plasticizers. SBR also experienced shrinkage (after drying) but its hardness returned to the baseline value. The dried volumes (and hardness values) of the silicone, SBR and fluorosilicone rubbers closely matched their original values, but the polyurethane specimen showed degradation with exposure to the test fuels containing ethanol or isobutanol. The DMA results showed that the test fuels effectively decreased T g for the fluorocarbons, but increased T g for the NBR materials. The T g values other elastomers were not affected by the test fuels.

Preliminary Compatibility Assessment of Metallic Dispenser Materials for Service in Ethanol Fuel Blends

The compatibility of selected metals representative of those commonly used in dispensing systems was evaluated in an aggressive E20 formulation (CE20a) and in synthetic gasoline (Reference Fuel C) in identical testing to facilitate comparison of results. The testing was performed at modestly elevated temperature (nominally 60 C) and with constant fluid flow in an effort to accelerate potential interactions in the screening test. Based on weight change, the general corrosion of all individual coupons exposed in the vapor phase above Reference Fuel C and CE20a as well as all coupons immersed in Reference Fuel C was essentially nil (<0.3 {micro}m/y), with no evidence of localized corrosion such as pitting/crevice corrosion or selective leaching at any location. Modest discoloration was observed on the copper-based alloys (cartridge brass and phosphor bronze), but the associated corrosion films were quite thin and apparently protective. For coupons immersed in CE20a, four different materials exhibited net weight loss over the entire course of the experiment: cartridge brass, phosphor bronze, galvanized steel, and terne-plated steel. None of these exhibited substantial incompatibility with the test fluid, with the largest general corrosion rate calculated from coupon weight loss to be approximately 4 {micro}m/y for the cartridge brass specimens. Selective leaching of zinc (from brass) and tin (from bronze) was observed, as well as the presence of sulfide surface films rich in these elements, suggesting the importance of the role of sulfuric acid in the CE20a formulation. Analysis of weight loss data for the slightly corroded metals indicated that the corrosivity of the test environment decreased with exposure time for brass and bronze and increased for galvanized and terne-plated steel. Other materials immersed in CE20a - type 1020 mild steel, type 1100 aluminum, type 201 nickel, and type 304 stainless steel - each appeared essentially immune to corrosion at the test conditions.