Spark Ignition Engine Exhaust Research Articles

Developing a novel downdraft fixed bed gasifier for hydrogen production from sawdust to improve an SI engine exhaust emissions

The presence of vast forests is the largest source of abundant biomass in Iran. Wood waste can be used as the primary source of energy generation. In the present research, sawdust was employed to produce the syngas. For this purpose, a downdraft gasifier was designed and the produced syngas was evaluated in a spark ignition (SI) engine. Based on results, the production yield of biohydrogen and its heating value at 960 ℃ were about 786 mL/g biomass and 3.75 MJ/m3, respectively. The synthesized syngas compositions were Hydrogen (13.82%), CH4 (1.52%), CO2 (2.75%), CO (13.6%), N2 (65.31%) and water vapor (3%). Increasing the temperature of the combustion zone inside the gasification reactor from 650 to 960 ℃, increased the H2, CH4, and CO contents of syngas. Moreover, the results indicated that, using syngas in engine reduces CO2 and UHC emissions about 58.6% and 16.6%, respectively compared to those for gasoline fuel.

Development of organic gas exhaust speciation profiles for nonroad spark-ignition and compression-ignition engines and equipment

The composition of exhaust emissions from nonroad engines and equipment varies based on a number of parameters, including engine type, emission control technology, fuel composition, and operating conditions. Speciated emissions data which characterize the chemical composition of these emissions are needed to develop chemical speciation profiles used for air quality modeling and to develop air toxics inventories. In this paper, we present results of an extensive review and analysis of available exhaust speciation data for total organic gases (TOG) for spark ignition (SI) engines running on gasoline/ethanol blends now in widespread use, and compression ignition (CI) engines running on diesel fuel. We identified two data sets best suited for development of exhaust speciation profiles. Neither of these data sets have previously been published. We analyzed the resulting speciation profiles for differences in SI engine exhaust composition between 2-stroke and 4-stroke engines using E0 (0% ethanol) and E10 (10% ethanol) blends, and differences in CI engine exhaust composition among engines meeting different emission standards. Exhaust speciation profiles were also analyzed to compare differences in maximum incremental reactivity (MIR) values; this is a useful indicator for evaluating how organic gases may affect ozone formation for air quality modeling. Our analyses found significant differences in speciated emissions from 2-stroke and 4-stroke SI engines, and between engines running on E0 and E10 fuels. We found significant differences in profiles from pre-Tier 1 CI engines, engines meeting Tier 1 standards, and engines meeting Tier 2 standards. Although data for nonroad CI engines meeting tier 4 standards with control devices such as particulate filters and selective catalyst reduction (SCR) devices were not available, data from highway CI engines suggest these technologies will substantially change profiles for nonroad CI engines as well (EPA, 2014c).Implications: The nonroad engine data sets analyzed in this study will substantially improve exhaust speciation profiles used to characterize organic gas emissions from nonroad engines. Since nonroad engines are major contributors to ambient air pollution, these profiles can considerably improve U.S. emission inventories for gaseous air toxics emitted from nonroad engines. The speciation profiles developed in this paper can be used to develop more accurate emission inputs to chemical transport models, leading to more accurate air quality modeling.

Combustion chamber geometry effects in spark ignition engine exhaust emissions

The paper presents experimental results showing the effect of hemispherical, cylindrical and oval bowls-in-piston on exhaust gases within the cylinder of spark ignition engines. Results indicate that bowls increase both heat transfer and flame speed. Consequently, flame ability must become wide to reduce both engine emissions and cycle combustion variability. Hemispherical effect ranked first on hydrocarbon and carbon monoxide emissions, followed by cylindrical then oval. Nitrogen oxides are in opposite direction, with oval ranked first, followed by cylindrical then hemispherical.

Variations in Speciated Emissions from Spark-Ignition and Compression-Ignition Motor Vehicles in California’s South Coast Air Basin

The U.S. Department of Energy Gasoline/Diesel PM Split Study examined the sources of uncertainties in using an organic compound-based chemical mass balance receptor model to quantify the contributions of spark-ignition (SI) and compression-ignition (CI) engine exhaust to ambient fine particulate matter (PM2.5). This paper presents the chemical composition profiles of SI and CI engine exhaust from the vehicle-testing portion of the study. Chemical analysis of source samples consisted of gravimetric mass, elements, ions, organic carbon (OC), and elemental carbon (EC) by the Interagency Monitoring of Protected Visual Environments (IMPROVE) and Speciation Trends Network (STN) thermal/optical methods, polycyclic aromatic hydrocarbons (PAHs), hopanes, steranes, alkanes, and polar organic compounds. More than half of the mass of carbonaceous particles emitted by heavy-duty diesel trucks was EC (IMPROVE) and emissions from SI vehicles contained predominantly OC. Although total carbon (TC) by the IMPROVE and STN protocols agreed well for all of the samples, the STN/IMPROVE ratios for EC from SI exhaust decreased with decreasing sample loading. SI vehicles, whether low or high emitters, emitted greater amounts of high-molecular-weight particulate PAHs (benzo[ghi]perylene, indeno[1,2,3-cd]pyrene, and coronene) than did CI vehicles. Diesel emissions contained higher abundances of two- to four-ring semivolatile PAHs. Diacids were emitted by CI vehicles but are also prevalent in secondary organic aerosols, so they cannot be considered unique tracers. Hopanes and steranes were present in lubricating oil with similar composition for both gasoline and diesel vehicles and were negligible in gasoline or diesel fuels. CI vehicles emitted greater total amounts of hopanes and steranes on a mass per mile basis, but abundances were comparable to SI exhaust normalized to TC emissions within measurement uncertainty. The combustion-produced high-molecular-weight PAHs were found in used gasoline motor oil but not in fresh oil and are negligible in used diesel engine oil. The contributions of lubrication oils to abundances of these PAHs in the exhaust were large in some cases and were variable with the age and consumption rate of the oil. These factors contributed to the observed variations in their abundances to total carbon or PM2.5 among the SI composition profiles.

Lean NO x reduction CuZSM5 catalysts: Evaluation of performance at the spark ignition engine exhaust

CuZSM5 catalysts, prepared by ion exchange of HZSM5 (Si/Al = 80), enable selective lean NO χ reduction at the spark ignition engine exhaust. All catalysts, even if exchanged to very high copper loading (556% apparent exchange level) give no evidence for segregated copper oxide phases. In the presence of water they are easily reduced in vacuum at 550°C and are stable to redox cycles (O 2, vacuum) treatments. Increasing Cu content to about 200% apparent exchange level results in increasing NO χ, CO and HC conversions. From 200 to 550% exchange CuZSM5 catalysts give similar performances. Preliminary investigation shows that after catalytic tests there is evidence for CuO formation only in the copper-richest catalysts.

Operation of a homogeneous exhaust manifold reactor

The thermal exhaust manifold reactor, used to reduce carbon base emissions in the exhaust of an Otto cycle engine, is a thermally insulated chamber replacing the exhaust manifold on the engine; when fresh air is added upstream of the reactor, homogeneous reactions can oxidize the emissions. The objective of the present work was to systematically investigate reactor operation in order to provide meaningful information for future reactor designs. The unique approach of simulating the spark ignition engine exhaust using a steady flow hot gas generator is implemented to eliminate the effects of the engine operation parameters. The main criterion for reactor design is its effectiveness in promoting self ignition of the mixture of engine exhaust and secondary air. It is demonstrated experimentally that the ignition is thermal in nature, which amplifies the importance of heat loss from and flow patterns within the reactor, and the optimum gas composition for promoting ignition is given. Furthermore, a correlation of these data, in terms of Damköhler's first similarity group, demonstrates the mechanism of stable and efficient reactor operation and establishes the principles of effective fluid mechanic design.

Physical and chemical characteristics of particulates in spark ignition engine exhaust

Physical and chemical characteristics of particulates in spark ignition engine exhaust