Exhaust Emission Control Research Articles

The Oxidation of Carbon Monoxide on Supported Platinum

Reliable kinetic rate data have not previously been available for the oxidation of carbon monoxide on platinum catalysts used in the control of automobile exhaust emissions. This paper discusses results of studies using an isothermal differential catalyst bed and confirms that mass transfer and pore diffusion did not control the reaction rate, so that the observed kinetics represent the true surface reaction rates.

The effect of fuel composition on atmospheric aerosol due to auto exhaust.

Aerosols attributable to automobile exhaust can be classified as two types—primary aerosol (initially present in the exhaust) and secondary aerosol (generated photochemically from hydrocarbons and nitrogen oxides in the exhaust). In this study, investigation was made of possible effects of motor-fuel composition on the formation of these aerosols. Secondary aerosol, of principal interest in this work, was produced by irradiating auto exhaust in Battelle-Columbus’ 610 ft3 environmental chamber. A limited number of determinations of primary aerosol in diluted auto exhaust was made at the exit of a 36 ft dilution runnel. Determination of both primary and secondary aerosol was based on light-scattering measurements. Exhaust was generated with seven full-boiling motor gasolines, both leaded and nonleaded, in a 1967 Chevrolet which was not equipped with exhaust-emission control devices. Changes in fuel composition produced a maximum factor of three difference in light scattering due to primary aerosol. Aerosol yields, for consecutive driving cycles on the same fuel, vary considerably; as a result, ranking the fuels on the basis of average primary aerosol yield was not very meaningful. In addition to fuel composition, the more important independent variables are initial SO2 concentration, relative humidity and initial hydrocarbon concentration. Statistical analysis of the data indicates that the seven test fuels can be divided into two arbitrary groups with regard to secondary aerosol-forming potential. The fuels in the lower light-scattering group had aromatic contents of 15 and 21%, while those in the higher light-scattering group had aromatic contents of 25, 48, and 55%. Although the fuels can be grouped on the basis of a compositional factor, the grouping of fuels with aromatic content ranging from 25 to 55% indicates that this compositional factor cannot be equated simply with aromatic content. In an associated study of the aerosol-forming potential of individual hydrocarbons prominent in auto exhaust, it was observed that aromatics produce substantially more photochemical aerosol than olefins and paraffins. However, experiments with binar/hydrocarbon mixtures containing aromatjcs, as well as in these exhaust experiments, a strong dependence of aerosol yield on the aromatic components is is not observed. Thus, the data indicate that the dependence of secondary aerosol formation on fuel factors is a complex one and cannot be predicted solely on the basis of a sirigle hydrocarbon component reactivity scale. The two types of automobile aerosol did not have the same dependence on fuel, composition. The variation in total light scattering attributable to primary plus secondary aerosol was less than that due to either component alone. It therefore was concluded that the light scattering due to automobile exhaust emissions in these experiments was not significantly affected by changing fuel composition.

Catalytic control of automobile exhaust emissions

Mechanical anto‐engine modifications in recent years have reduced exhaust emission levels, but further lowering of concentrations might be achieved by the application of catalytic devices. The objective of this survey has been to examine the effectiveness of current catalytic devices designed for auto‐exhaust control.

The Development of an Electronically Controlled Petrol Injection System

The requirements of the modern automotive petrol engine in relation to higher specific power outputs while retaining good driveability and satisfying the impending exhaust emission control regulations, motivated an investigation into the potential of petrol injection. Consideration of the control requirements and accuracy necessary led, at an early stage, to the selection of electronic control on the basis of control capability, long term reliability, relatively low cost and the potential for future development. The fuel system was designed round the electronic control, manifold injection being used instead of direct injection on the basis of simplicity, lower cost and greater installation flexibility. The original system concept has changed only in detail, development effort being applied to the refinement of the system components to achieve a high standard of performance and the facility to apply the system with minimal modification to a wide range of engine types. The system is described in some detail and typical examples of the system performance on vehicles are presented.

Exhaust Emission Measurement and Control

Exhaust Emission Measurement and Control

Paper 13: The New Vöv (Public Transport Authority) Model O 305 Standard Service Bus

If the drift to individual means of transport is to be avoided, the city bus must be made more attractive in its driving comfort and performance, and provide a maximum degree of safety. Vehicles of advanced design requiring a minimum of maintenance, and frames and superstructures constructed according to the latest conceptions, are absolutely necessary for an economic and reliable city bus. Easy-to-operate controls facilitate the driver's task and are an added safety measure. The standard O 305 regular service bus, designed in accordance with the regulations of the Public Transport Authority (Verband Öffentlicher Verkehrsbetriebe), meets these demands. The experimental electric bus with hybrid drive appears to be a solution to the exacting requirements of future traffic with regard to exhaust emission control.

Second Paper: Recent Developments in Exhaust Manifold Reactor Systems

Exhaust emission control systems employing air injection and exhaust manifold reactors in place of conventional exhaust manifolds have been developed to control vehicle emissions to 0·25 gram (20 p.p.m.) of hydrocarbons and 5·0 grams (0·22 per cent) of carbon monoxide per mile. These low emission levels have been achieved with good driveability, good vehicle performance and very little loss in fuel economy. Durability tests of a number of exhaust manifold reactor systems indicate that acceptable life in consumer service can be attained. Non-nickel alloy steels developed by specialty steel manufacturers, and based on the iron-chromium- aluminium system, appear to be useful materials of construction for reactors. These alloys coupled with the now demonstrated simplifications in reactor design offer one route to lower ultimate costs of these units. The commercial development and application of exhaust manifold reactor systems seems entirely feasible.

Paper 15: Factors in the Design of Automatic Flow Benches for Carburettor Inspection

This paper examines the basic parameters concerned in the definition of automated flow bench equipment for the production control of carburettor metering standards—particularly as they are concerned in exhaust emission control programmes—and discusses some of the problems encountered during the design and development phases.

Paper 12: Some Methods of Controlling Exhaust Emissions during Deceleration

Paper 12: Some Methods of Controlling Exhaust Emissions during Deceleration