Engine Exhaust Aftertreatment System Research Articles

Component Level Failure Analysis of Mounting Strap Joint Fitted on Vehicle Engine Exhaust After-Treatment System

Exhaust Gas Processors (EGP) or Exhaust After Treatment Systems (EATS) are usually mounted on vehicle chassis or engine body with the help of mounting straps due to its ease of installation. It is prescribed for any industry to manufacture an optimized design of strap joint and duly test it before making an entry to the market. There is no standard method available to be followed by the industry for strap validation at an earlier stage. Most of the strap joint designed and tested based either on MAST test (done in the later stages) or on the experience. So, to test the strap joint at an earlier stage there is a need to design a component level strap joint validation method with a goal to assess the durability of strap joint vulnerable to fatigue failures due to vibration over-amplification in a bracketed after-treatment assembly while able of detecting any design flaws and eliminating or reducing numbers of potential test induced failures. The objective of this work is to define and document a systematic approach for component level strap joint validation method used to mount after treatment system components. Due to geometrical complexity and nature of material, geometrical nonlinearity and material nonlinearity were considered in the analysis. Also, for getting the most realistic results contact nonlinearity was also considered. And finally, out of various approaches investigated, an approach which was able to replicate failures in a more exact manner comparable to assembly level test was recommended as the component level strap validation method.

Study on Selection of Diesel Engine Exhaust After-Treatment System Materials and Emission Performance for Genset Applications

The use of diesel engines for the transportation sector is ubiquitous and covers a broad continuum, like buses, trucks, agriculture, construction equipment, generators, and industrial applications. However, because of their increased use of off-road engines, they contribute more emissions in various sectors than on-road. As a result, worldwide, regardless of ongoing emission control efforts, these off-road, stationary engines also continue to be a substantial source of air pollutant emissions in the United States, European Union and Asian markets. Accordingly, while improving emissions performance, the selection of after-treatment system materials and the use of compatible after-treatment specification selections are also critical. This is only possible by effectively combining clean diesel technologies such as Fuel Injection Equipment (FIE), Turbocharger with Intercooler (TCIC), Cooled Exhaust Gas Recirculation (C-EGR), and after-treatment systems like Diesel Oxidation Catalyst (DOC), Selective Catalytic Reduction (SCR), and Diesel Particulate Filter (DPF). Overall, in this study, the influence of after-treatment system configurations and their effect on emission reduction performance are studied for three different DOC specifications based on emission testing for catalyst and size optimization. With the selected DOC catalyst specification, suitable combinations of DPF and SCR specifications are optimized further using GT-SUIT software simulation. This study was carried out during the conversion of a 15 kW NA engine to a 27 kW TCIC engine to meet diesel engine emission norms.

Particle emissions from a modern heavy-duty diesel engine as ice nuclei in immersion freezing mode: a laboratory study on fossil and renewable fuels

Abstract. We studied ice-nucleating abilities of particulate emissions from a modern heavy-duty diesel engine using three different types of fuel. The polydisperse particle emissions were sampled during engine operation and introduced to a continuous-flow diffusion chamber (CFDC) instrument at a constant relative humidity RHwater=110 %, while the temperature was ramped between −43 and −32 ∘C (T scan). The tested fuels were EN 590 compliant low-sulfur fossil diesel, hydrotreated vegetable oil (HVO), and rapeseed methyl ester (RME); all were tested without blending. Sampling was carried out at different stages in the engine exhaust aftertreatment system, with and without simulated atmospheric processing using an oxidation flow reactor. In addition to ice nucleation experiments, we used supportive instrumentation to characterize the emitted particles for their physicochemical properties and presented six parameters. We found that the studied emissions contained no significant concentrations of ice-nucleating particles likely to be of atmospheric relevance. The substitution of fossil diesel with renewable fuels, using different emission aftertreatment systems such as a diesel oxidation catalyst, and photochemical aging of total exhaust had only minor effect on their ice-nucleating abilities.

Working Cycle requirements for an electrified architecture of a vertical feed mixer vehicle

In the last years, the need for lower pollutant emissions has become one of the most discussed topic worldwide. Governments establish stricter regulations almost yearly in order to push the industry towards more efficient machines or, at least, lower harmful gas emissions. Agriculture is experiencing the same trend with strict regulations which force manufacturers to the massive use of diesel engine exhaust after-treatment systems. At the same time, industries are considering other options that can satisfy regulations and also add functionalities to their products. This research wants to show the results of the study which led to the first electric prototype of a self-propelled vertical feed mixer. A methodological approach in collaboration with an Italian feed mixer wagons manufacturer, allowed to characterize the traditional machine in all its working conditions leading to the necessary requirements for the design of the final electric architecture.

Cu-zeolite catalysts for NOx removal by selective catalytic reduction with NH3 and coupled to NO storage/reduction monolith in diesel engine exhaust aftertreatment systems

Coupled NSR-SCR systems comprising a Pt-BaO/Al2O3 NSR monolith and Cu/CHA, Cu/ZSM-5 or Cu/BETA SCR catalysts are prepared and tested for NOx removal from diesel and lean burn engines exhaust gases. The Cu/zeolite catalysts are characterized by ICP-AES, XRD, N2 adsorption-desorption, NH3-TPD and H2-TPR. The physico-chemical characteristics of fresh catalysts and aged under 5% steam/Ar at 750°C for 16h and are compared, resulting in the Cu/CHA with much higher hydrothermal resistance to the loss of textural and structural properties. The single-SCR, single-NSR and coupled NSR-SCR catalytic performance is studied including the conversion of NO and NH3, slip of NH3, and N2O and NO2 yields. Cu/CHA presents the SCR wider temperature window, eventually 100% NO conversion from 220 to 380°C, even maintained after severe aging. For application in the NSR-SCR technology, the NH3 generated in the NSR catalyst during the rich period is able to achieve higher NO conversion reducing significantly the slip of NH3 (negligible at 200°C and above), very few amount of N2O at any temperature, and small production of NO2 only at higher temperatures. This improvement of activity and selectivity is particularly enhanced with the coupled NSR-Cu/CHA system, which is also maintained when the catalyst is deposited on the cordierite monolith substrate, as in the case of real application.

Control-Oriented Modeling and Model-Based Estimation and Control for Diesel Engine Aftertreatment Systems

This article provides an overview of control-oriented modeling and model-based estimation and control for diesel engine aftertreatment systems. The chemical reactions and physical processes that occur in diesel engine after-treatment systems are quite complex. Computational models describing the chemical reaction kinetics, flow, and thermo-physical phenomena in engine exhaust aftertreatment systems have been coming forth since the 1960s when catalytic converters were introduced for vehicle applications {AQ: This word ‘catalystic’ is not found in standard dictionaries. Please check and correct if necessary.}. Such models can provide insightful understanding and mathematical descriptions on the chemical reactions, mass transfer, and heat transfer processes in one-dimensional and multi-dimensional fashions. The primary purpose of diesel engine aftertreatment system control-oriented models is to serve for the designs of real-time aftertreatment control and fault-diagnosis systems to reduce tailpipe emissions during real-world vehicle operations. Because such control-oriented models contain physically-meaningful parameters of the actual treatment systems, the model-based estimation and control algorithms can have excellent generalizability among different platforms.

Study of SCR cold-start by energy method

The cold-start of a prototype diesel engine exhaust aftertreatment system was analyzed using a simplified energy balance to study the impact of system design changes on the performance of the selective catalytic NOx reduction reactor. The simplified energy balance method is shown to be a viable tool for system-level analysis of the aftertreatment performance. The results indicate that without an external energy supply the best way to shorten the selective catalytic reduction (SCR) reactor light-off time is to reduce the system thermal inertia by including a metallic diesel oxidation catalyst (DOC) and moving the SCR reactor upstream. Such optimization of the aftertreatment architecture is found to significantly reduce SCR light-off time for the configurations examined. Electrical heating applied to the SCR and DOC reactors can also reduce the light-off time. The system architecture optimization, however, is subject to vehicle under-hood packaging restrictions. To meet more stringent emission standards in the future, a combination of architecture optimization and electrical heating will be required.

Architecture Design and Analysis of Diesel Engine Exhaust Aftertreatment System and Comparative Study with Close-coupled DOC-DPF System

Architecture Design and Analysis of Diesel Engine Exhaust Aftertreatment System and Comparative Study with Close-coupled DOC-DPF System

Computer aided engineering in diesel exhaust aftertreatment systems design

Computer aided engineering (CAE) methodologies are increasingly being applied to assist the design of spark-ignition (SI) engine exhaust aftertreatment systems in view of the stage III and IV emissions standards. Following this trend, the design of diesel exhaust aftertreatment systems is receiving more attention owing to the capabilities of recently developed mathematical models. The design of diesel exhaust systems must cope with three major aftertreatment categories: diesel oxidation catalysts, diesel particulate filters and de-NOx catalytic converters. An integrated CAE methodology that could assist the design of all these classes of systems is described in this paper. It employs the following computational tools: a computer code for modelling transient exhaust system heat transfer, a computer code for modelling the transient operation of a diesel oxidation or a de-NOx catalytic converter, a database containing chemical kinetics data for a variety of oxidation and de-NOx catalyst formulations and a computer code for modelling the loading and regeneration behaviour of a wall-flow filter, assisted by catalytic fuel additives. Application of the CAE methodology, which helps the exhaust aftertreatment system design engineer to meet the future emissions standards, is highlighted by referring to a number of representative case studies.