E. W. Kaiser

The Effect of Oil Layers on the Hydrocarbon Emissions from Spark-Ignited Engines

Abstract Measured amounts of oil were added to the engine cylinder of a single-cylinder CFR engine to determine the effect of oil layers on exhaust hydrocarbon emissions. The exhaust hydrocarbon concentration increased in proportion to the amount of oil added when the engine was fueled on isooctane. Addition of 0·6 cm3 of oil produced an increase of 1000 ppmC in exhaust hydrocarbon emissions at a coolant temperature of 320°K. Gas chromatographic analysis of the exhaust determined that fuel and fuel oxidation species, not oil oxidation products, were responsible for most of the increase. Similar experiments performed with propane fuel showed no increase in exhaust emissions when oil was added to the cylinder. These measurements have determined that the increase in tailpipe hydrocarbon concentration consists of fuel related species and is proportional to both the amount of oil added and the solubility of the fuel in the oil. Thus, we believe that the principal source of this increase in exhaust hydrocarbon ...

In-Cylinder Measurements of Wall Layer Hydrocarbons in a Spark Ignited Engine

Abstract The hydrocarbon emissions process for the conventional, spark ignited, IC engine has been studied experimentally using a rapid acting gas sampling valve mounted in the combustion chamber wall. The sampling valve was electrohydraulically actuated. Design of the valve specifically allowed sampling in the vicinity of the wall quench layer with minimum leakage and crevice contributions to the measured hydrocarbon concentrations. Experimental results presented give substantial evidence that hydrocarbons remaining in a wall quench layer are not a major source of exhaust hydrocarbon emissions. Measurements of species concentrations as a function of time in the cycle and sample flow rate indicate that after flame arrival and quenching at the cold walls, hydrocarbons in the quench layer are rapidly and extensively oxidized within 2 msec. By use of an analytical model for the gas flow profile into the sampling valve, conservative upper limit calculations have been made of the quench layer contribution to t...

The Effect of Fuel and Operating Variables on Hydrocarbon Species Distributions in the Exhaust from a Multicylinder Engine

Abstract Measurements of the concentrations of individual exhaust hydrocarbon species have been made as a function of engine operating variables (φ, rpm, EGR, spark timing, and coolant temperature) in a 2·3-liter four-cylinder engine. Three fuels were used in these experiments: propane, isooctane (2,2,4-trimethylpentane), and an unleaded gasoline (indolene clear). The results show that a change in operating variable can change not only the total hydrocarbon concentration but also the distribution of species in the exhaust. All three fuels show similar trends when an operating variable is changed. Fuel-air equivalence ratio is a critical parameter in controlling exhaust hydrocarbon emissions. Beginning near stoichiometric, the total hydrocarbon concentration and the percentage contributions of methane and acetylene to the exhaust increase as the mixture becomes richer. These species contribute less than 2 percent to the total hydrocarbon emissions at <0.95. Their contribution rises to 15–25 percent at φ...

A combustion bomb study of the hydrocarbon emissions from engine crevices

Abstract Two combustion bombs manufactured from a Ford 1.6L Escort production engine were used to determine the effects of engine crevice volumes on hydrocarbon emissions. Since these combustion bombs were used as static reactors, the results cannot be directly applied to an operating engine but they focus attention on the major hydrocarbon-producing crevices in an actual engine geometry. During Ihis propane-fueled experiment, the crevices were sequentially filled with epoxy or viton rubber, and after filling each crevice, the exhaust hydrocarbon emission was measured by gas chromatography. This provided a quantitative measurement of the hydrocarbon emission from each crevice. For these reactors, the ring-pack crevices produced approximately 80.5 percent of the total scaled hydrocarbon emission, while the head gasket and spark plug threads produced approximately 12.5 percent and 5 percent, respectively. All other hydrocarbon sources produced less than 2 percent of the total scaled hydrocarbon emissionfrom...

An experimental study of hydrocarbon emissions from closed vessel explosions

Two combustion bombs are used to determine the exhaust hydrocarbon emission after laminar flame propagation through the reactors. Propane and air are used as fuel and oxidizer, and gas chromatography is used to analyze, the emission, gases. Data are taken over an initial pressure range from 50 kPa to 400 kPa and from an equivalence ration of 0.7 to the soot limit at 2.0. During experimentation, extreme care is taken to keep the reactor vessels clean while reducing crevice storage volumes using indium seals and displacement materials. The results under lean conditions indicate that the charging and subsequent outgassing of fuel molecules from storage volumes into a relatively cold bulk gas is the primary cause of exhaust emissions. This is consistent with recent numerical results under near stoichiometric conditions, indicating that flame quench hydrocarbons rapidly diffuse and oxidize, producing less unburnt material than previously thought. Under these conditions, the levels of exhaust hydrocarbons are observed to be two orders of magnitude lower than previously reported in the literature. Furthermore, under rich conditions, >1.2, the results indicate that processes other than storage effects and wall-quenching—possibly occurring in the bulk gas—may be the cause of the exhaust hydrocarbon emission from clean vessels.

Quench Layer Contribution to Exhaust Hydrocarbons from a Spark-Ignited Engine

INTRODUCTION Hydrocarbons remaining in a wall quench layer have been proposed as a major source of hydrocarbon emissions in spark-ignited internal combustion engines (Daniel and Wentworth, 1962). Additional experiments using wall mounted sampling valves were subsequently carried out by Daniel (1967), Muller and von Watzdorf (1968), Weiss et al. (1979), and Henningsen and Qvale (1980). Our paper presents the results of an experimental study of the quench layer also using a wall mounted sampling valve. The valve was electrohydraulically actuated and had uniquely small leakage and crevice characteristics. Our results do not support the contention that the wall quench layer is a major source of exhaust emissions. Hydrocarbons from other sources, as yet not quantified, such as those emitted from ring crevices, deposits or oil films appear to be likely contributors to exhaust hydrocarbons (Wentworth, 1971; Haskell and Legate, 1972; and Kaiser et al., 1980).

Storage and Partial Oxidation of Unburned Hydrocarbons in Spark-Ignited Engines - Effect of Compression Ratio and Spark Timing

Abstract The concentrations of the individual hydrocarbon species in the exhaust gases from a single-cylinder CFR engine have been measured. The effects of compression ratio and spark timing on these emissions have been observed using propane, isooctane (2,2,4-trimethylpentanerpar; and indolene clear fuels. The results show that total hydrocarbon emissions increase rapidly as the compression ratio increases and decrease sharply as the spark timing is retarded relative to MBT at a constant compression ratio. Changes in the concentration of unburned fuel in the exhaust contribute the most to these variations. These observations are consistent with the predicted increase in crevice and oil film storage of unburned hydrocarbons at higher compression ratio because of the higher peak pressures. They also agree with the predicted increase in post-flame burnup of stored hydrocarbons in the hotter cylinder gases encountered during low compression ratio or retarded spark operation.

Chemical Species Profiles of Laminar propane-Air Flames

Abstract The mole fractions of all CI-C4 hydrocarbons, CO, C02, Nz, and Oz have beenmeasured through the luminous zone and into the post-flame gases of laminar propane-airflames at one atmosphere pressure. The experiments were performed on a flat-flame burner, andsamples were withdrawn by an uncooled quartz probe for gas chromatographic analysis. Measure-ment of the perturbation of the species distributions by the probe sampling technique have beencarried out where possible. Concentration-distance profiles have been obtained at three fuel-airequivalence ratios (0.63, 1.0, and 1.46) and at two flame temperatures (1680 and 1880°K) for thefuel-rich equivalence ratio. These results are compared with predicted concentrations obtainedby flame model calculations which include extensive chemical reaction mechanism sets. Thereare deviations of up to a factor of 10 between the predicted and the measured concentrations ofcertain species. These measurements provide crucial data from which better reaction mechanismsan...

An Electrohydraulic Gas Sampling Valve with Application to Hydrocarbon Emissions Studies

Design and development of an electrohydraulically actuated gas sampling valve is presented for use in auto engine combustion studies. The gas sampling valve is coupled to a gas chromatograph to measure concentrations of major species components. Initial studies have focussed upon determining species profiles near the wall at specific times after flame arrival at one sampling location in the engine cylinder. The results indicate that the contribution of wall quench layer hydrocarbons to the engine exhaust is substantially smaller than previously estimated.

Effect of Fuel-Air Equivalence Ratio and Temperature on the Structure of Laminar Propane-Air Flames

Abstract Gas samples have been withdrawn from laminar atmospheric-pressure propane-air flat flames using an uncooled quartz probe with a 0.1 mm diameter orifice. The samples (60 torr total pressure) are analyzed by gas chromatography for all C11,-C44, hydrocarbons, CO1 C02, N2, and 02. The Quartz probe is movable vertically, allowing measurement of the concentrations of stable molecules as a function of height above the burner with vertical resolution better than 0.2 mm. During lean (Φ=0.6-0.9) operation, intermediate hydrocarbon products (C2H2, C2H4, C3H6, CH4) are seen in the luminous zone at concentrations of 200-2000 ppm. All hydrocarbons decrease to below I ppm within 0.25 mm above the top of the luminous zone. When the flame is rich (Φ= 1.2-1.4), a peak in the intermediate hydrocarbons is again seen in the luminous zone, but the decay rates of C2H2 and CH4 in the post-luminous zone are much slower. These species are present at concentrations of 100-1000 ppm several mm beyond the luminous zone for Φ>...