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This paper describes the joint development by Tenneco and Pi Shurlok of a complete diesel engine aftertreatment system for controlling particulate matter emissions. The system consists of a DOC, DPF, sensors, controller and an exhaust fuel injection system to allow active DPF regeneration. The mechanical components were designed for flow uniformity, low backpressure and component durability. The overall package is intended as a complete PM control system solution for OEMs, which does not require any significant additions to the OEM's engine control strategies and minimizes integration complexity. Thus, to make it easier to adapt to different engine platforms, ranging from small off-road vehicle engines to large locomotive engines, model-based control algorithms were developed in preference to map-based controls.

An active diesel particulate filter (DPF) regeneration system is evaluated, which applies secondary fuel injection (SFI) directly within the exhaust system upstream of a diesel oxidation catalyst (DOC). Diesel fuel is oxidized in the presence of a proprietary catalyst system, increasing exhaust gas temperatures in an efficient and controlled manner, even during low engine-out gas temperatures. The exotherms produced by secondary fuel injection (SFI) have been evaluated using two different DOC volumes and platinum catalyst loadings. DOC light-off temperatures were measured using SFI under steady-state conditions on an engine dynamometer. A ΔT method was used for the light-off temperature measurements – i.e., the minimum DOC inlet gas temperature at which the exothermic reaction increases the outlet gas temperature 20°C or greater than the inlet temperature.

A mathematical model has been developed for the investigation of mechanical vibrations of an exhaust system under road load excitation. For practical reasons, the vehicle body and the exhaust system has been considered as masses connected by springs and dampers. Non-linear damping characteristics of the vehicle tires and the exhaust isolators have been included in the model. Equations of motion have been solved in the MatLab environment, and transfer functions of the system and response to input signals representing the power spectrum density (PSD) of the road profile have been obtained for each mass in the system. The model developed has been verified through comparisons to the acceleration time history recordings on a proving ground and has been used for the parametric studies. The paper describes a comparison of model results with experimental observations, and predictions of parametric studies.

Road inputs are one of the most significant components of operational loading of motor vehicles and their exhaust systems. Even if road profiles remain the same, the response spectrums measured on exhaust system components vary for different vehicle and exhaust system combinations. Existing exhaust system product development and design approval procedures require multi-channel data acquisition on vehicles under specified driving conditions and at proving grounds to cover all representative customer usage events. After analysis and reduction, damage relevant sections of this data package will be used for test lab simulation purposes. This vehicle instrumentation and data acquisition process is very time consuming and cost intensive. The method presented here is based on the calculation of the dynamic characteristics of each road segment, or road events using road measured acceleration time histories, and lab measured transfer functions of vehicle body and suspension.

Diesel Particulate Filters (DPFs) have been successfully applied for several years to reduce Particulate Matter (PM) emissions from on-highway applications, and similar products are now also applied in off-highway markets and retrofit solutions. Most solutions are catalytically-based, necessitating minimum operating temperatures and demanding engine support strategies to reduce risks [1, 2, 3, 4, 5, 6, 7, 8]. An ignition-based thermal combustion device is applied with Cordierite and SiC filters, evaluating various DPF conditions, including effects of soot load, exhaust flow rates, catalytic coatings, and regeneration temperatures. System designs are described, including flow and temperature uniformity, as well as soot load distribution and thermal gradient response.

Diesel Particulate Filters have been successfully applied for several years to reduce Particulate Matter (PM) emissions from on-highway applications, and similar products are now also applied in off-highway markets and retrofit solutions. As soot accumulates on the filter, backpressure increases, and eventually exhaust temperatures are elevated to burn off the soot, actively or passively. Unfortunately, in many real-world instances, some duty cycles never achieve necessary temperatures, and the ability of the engine and/or catalyst to elevate exhaust temperatures can be problematic, resulting in overloaded filters that have become clogged, necessitating service attention. An autonomous heat source is developed to eliminate such risks, applying an ignition-based combustor that leverages the current diesel fuel supply, providing necessary temperatures when needed, regardless of engine operating conditions.

In order to scientifically approach the design of mounting systems for substrates in emissions control systems, it is essential to characterize the behavior of the involved materials, particularly the support mat. Manufacturing processes and various in-field conditions impact the long term performance of the support mat, and life-long emissions performance is critically dependent on its ability to retain the substrate throughout the intended life. Therefore, to ensure product robustness, the behavior during operation of all available support mats must be appropriately characterized to determine the technical layout in specific applications. This paper addresses three common characterization tests, developed internally and externally. Additionally, equipment improvements to minimize artifacts in test results as well as the development of a new mat test for manufacturing methods are addressed.

An active Diesel Particulate Filter (DPF) regeneration technology has been developed in which diesel fuel is oxidized in the presence of a proprietary catalyst system, regenerating the DPF in an efficient and controlled manner. Several important benefits for such a system include light off at low exhaust temperatures, which allows active regeneration over a wide range of vehicle uses, the ability to heat the DPF uniformly without hot spots or uncontrolled temperature extremes, lower backpressures and fuel penalty costs and a control strategy that could be substantially independent of the engine management system. The Xonon Fuel Combustor (XFC™) provides for active regeneration of the DPF at various vehicle loads and speeds. System attributes include activation at engine exhaust temperatures as low as 220°C and an outlet temperature that can be efficiently controlled over a wide range, as high as 700°C.

This study investigates the passive regeneration behavior of diesel particulate filters (DPFS) with various PGM loadings under different engine operating conditions. Four wall-flow DPFs are used; one uncoated and three wash-coated with low, medium, and high PGM loadings, with and without an upstream diesel oxidation catalyst (DOC). DPFs with variable pre-soot loads are evaluated at two steady state temperatures (300°C and 400°C), as well as across three levels of transients based on the 13-mode ESC cycle. Passive regeneration rates are calculated based on pre and post soot gravimetric measurements along with accumulated soot mass rates for specified exhaust mass flow rates and temperatures. Results illustrate the effect of temperature, NO₂ content, and soot loading on passive regeneration without upstream DOCs or DPF wash coatings.