Browse Topic: Diesel exhaust emissions
Upcoming, stricter diesel exhaust emissions standards will likely require aftertreatment architectures with multiple diesel exhaust fluid (DEF) introduction locations. Managing NH3 slip with technologies such as an ammonia slip catalyst (ASC) will continue to be critical in these future aftertreatment systems. In this study, we evaluate the impact of SO2 exposure on a state-of-the-art commercially available ASC. SO2 is co-fed at 0.5 or 3 ppmv to either approximate or accelerate a real-world exhaust SO2 impact. ASC performance during sulfur co-feeding is measured under a wide variety of simulated real-world conditions. Results indicate that the loss of NO conversion during SCR is dependent on the cumulative SO2 exposure, regardless of the inlet SO2 concentration. Meanwhile, N2O formation under SCR conditions is nonlinearly affected by SO2 exposure, with formation increasing during 0.5 ppmv SO2 exposure but decreasing in the presence of 3 ppmv SO2. TPO experiments reveal the formation of
Exhaust Gas Recirculation (EGR) coolers are widely used on diesel engines to reduce in-cylinder NOx formation. A common problem is the accumulation of a fouling layer inside the heat exchanger, mainly due to thermophoresis that leads to deposition of particulate matter (PM), and condensation of hydrocarbons (HC) from the diesel exhaust. From a recent investigation of deposits from field samples of EGR coolers, it was confirmed that the densities of their deposits were much higher than reported in previous studies. In this study, the experiments were conducted in order to verify hypotheses about deposit growth, especially densification. An experimental set up which included a custom-made shell and tube type heat exchanger with six surrogate tubes was designed to control flow rate independently, and was installed on a 1.9 L L-4 common rail turbo diesel engine. The test cycle and conditions were higher PM/ lower HC with 75°C coolant temperature for 1.5h, then lower PM/ higher HC with 75°C
This specification describes a method and acceptance criteria for testing automotive wire harness retainer clips. Retainer clips are plastic parts that hold a wire harness or electrical connector in a specific position. Typical plastic retainers work by having a set of “branches” that can be inserted into a hole sized to be easy to install but provide acceptable retention. This specification tests retainer clips for mechanical retention when exposed to the mechanical and environmental stresses typically found in automotive applications over a 15-year service life. This specification has several test options to allow the test to match to the expected service conditions. The variability of applications typically arises from different ambient temperatures near the clip, different proximity to automotive fluids, different exposure to standing water or water spray, and different thicknesses of the holes that the clip is inserted into. Clips are typically inserted into sheet or rolled metal
This SAE Standard defines the test conditions, procedures, and performance requirements for circuit breakers in ratings up to and including 200 A. The document includes automatic reset, modified reset, and manually reset types of circuit breakers for 12 VDC, 24 VDC, and 48 VDC electrical systems. Some circuit breakers may have dual voltage ratings (AC and DC); however, this document evaluates DC performance only
Heavy Duty Vehicle (HDV) Diesel emission regulations are set to be tightened in the future. The introduction of PN PEMS testing for Euro VI-e, and the expected tightening of PM/NOx targets set to be introduced by CARB in the US beyond 2024 are expected to create challenging tailpipe PN conditions for OEMs. Additionally, warranty and the useful life period will be extended from current levels. Improved fuel efficiency (reduction of CO2) also remains an important performance criteria. Furthermore, future non-road diesel emission regulations may follow tighten HDV diesel emission regulations contents, and non-road cycles evaluation needs to be considered as well for future. In response to the above tightened regulation, for Diesel Particulate Filter (DPF) technologies will require higher PN filtration performance, lower pressure drop, higher ash capacity and better pressure drop hysteresis for improved soot detectability. Additionally, thermal management of aftertreatment system has
The urea-selective catalyst reduction system implemented in commercial vehicles facilitates ensuring compliance with the NOx regulation limit. A significant challenge in urea injection is to comprehend its decomposition chemistry that often leads to the formation of unfavorable deposits in the exhaust system unit. Due to the complex interaction of the multiphase fluid flow and transport processes, a significant degree of uncertainty is associated with the identification of the interacting factors that control the deposit initiation and their growth. A systematic investigation was conducted through numerous experiments to study the factors controlling the urea deposit that guide innovation for new product development. For the first time, the effect of pressure on urea deposits was investigated by heating an aqueous urea solution in a closed system maintained between 30 and 200 psi. Chemical characterization procedure was conducted using liquid chromatography-multiple reaction monitoring
Conventional methods of physicochemical models require various experts and a high measurement demand to achieve the required model accuracy. With an additional request for faster development time for diagnostic algorithms, this method has reached the limits of economic feasibility. Machine learning algorithms are getting more popular in order to achieve a high model accuracy with an appropriate economical effort and allow to describe complex problems using statistical methods. An important point is the independence from other modelled variables and the exclusive use of sensor data and actuator settings. The concept has already been successfully proven in the field of modelling for exhaust gas aftertreatment sensors. An engine-out nitrogen oxide (NOX) emission sensor model based on polynomial regression was developed, trained, and transferred onto a conventional automotive electronic control unit (ECU) and also proves real-time capability. Within this study several approaches are
This paper discusses the development of an all speed governed diesel-natural gas dual fuel engine for agricultural farm tractor. A 45 hp, 2.9 liters diesel-natural gas dual fuel engine with a novel closed loop secondary fuel injection system was developed. A frugal approach without any modification of the base mechanical diesel fuel injection system was followed. This approach helped to minimize the cost impact, while meeting performance and emissions at par with neat diesel operation. Additional cost on gas injection system is redeemed by cost savings on diesel fuel. The dual fuel technology developed by Mahindra & Mahindra Ltd., substitutes on an average approximately 40% of diesel with compressed natural gas, meeting the TREM III A emission norms for dual fuel while meeting all application requirements. The governing performance of the tractor was found to be superior than base diesel tractor. A prototype dual fuel tractor was tested for all field applications including puddling
To avoid frequent regeneration intervals leading to expeditious ageing of the catalyst and substantial fuel penalty for the owner, it is always desired to estimate the soot coming from diesel exhaust emission, the soot accumulated and burnt in the Diesel Particulate Filter (DPF). Certain applications and vehicle duty cycles cannot make use of the differential pressure sensor for estimating the soot loading in the DPF because of the limitations of the sensor tolerance and measurement accuracy. The physical soot model is always active and hence a precise and more accurate model is preferred to calibrate & optimize the regeneration interval. This paper presents the approach to estimate the engine-out soot and the accumulated soot in the DPF using a graphical calculation tool (AVL Concerto CalcGraf™). The tool reduces the efforts of driving different duty cycles multiple times on the testbed and recurrent vehicle trips for data collection while calibrating the soot models, hence saving
Commercial vehicles are moving in the direction of improving brake thermal efficiency while also meeting future diesel emission requirements. This study is focused on improving efficiency by replacing the variable geometry turbine (VGT) turbocharger with a high-efficiency fixed geometry turbocharger. Engine-out (EO) NOX emissions are maintained by providing the required amount of exhaust gas recirculation (EGR) using a 48 V motor driven EGR pump downstream of the EGR cooler. This engine is also equipped with cylinder deactivation (CDA) hardware such that the engine can be optimized at low load operation using the combination of the high-efficiency turbocharger, EGR pump and CDA. The exhaust aftertreatment system has been shown to meet 2027 emissions using the baseline engine hardware as it includes a close coupled light-off SCR followed by a downstream SCR system. A parametric analysis for improving engine efficiency is provided using the high-efficiency turbocharger, EGR pump and CDA
This SAE Recommended Practice describes the recommended methods for testing flexible harness coverings for use on ground vehicle electrical distribution systems. This SAE Recommended Practice shall apply to all tapes, extruded tube, and textile tube
Diesel Exhaust Fluid (DEF) systems are required to function in cold ambient temperatures below the freezing point of DEF. Manufacturers may demonstrate compliance by following an EPA guidance procedure described below [2], using whole vehicles at winter test sites at −18 deg C or lower. However, commercial trucks may have multiple variants with different DEF system layouts, so it is impractical to test every possible configuration. A climatic chassis dynamometer (CCD) can also be used for this test, but this is still expensive and time consuming, and does not address the problem of complexity. Instead, much time and expense can be saved by using simulation methods to identify worst case configurations, and to demonstrate with confidence that a limited number of tests will cover the whole possible range. This methodology can further be used to show that a range of vehicles can be represented with selected rig tests in a cold chamber. Such a methodology depends on the ability to generate
Cu-SSZ-13 selective catalytic reduction (SCR) catalysts are broadly applied in diesel aftertreatment systems for the catalytic conversion of oxides of nitrogen (NO + NO2). Diesel exhaust contains a wide range of water vapor concentrations depending on the operating condition. In this study, we evaluate the impact of water vapor on the relevant SCR catalytic functions including NOx conversion, NO oxidation, NH3 oxidation, and N2O formation under both standard and fast SCR conditions. Reactor-based experiments are conducted in the presence and absence of water vapor. Results indicate that water vapor can have both a positive and negative impact on low temperature NOx conversion for standard SCR reaction. At low inlet NOx concentrations, the presence of water vapor has a negative effect on NOx conversion, whereas, at high inlet NO concentrations, water vapor improves NOx conversion. At high temperatures, water vapor has a beneficial effect on NOx conversion at all NOx inlet concentrations
Particulate matter (PM) and NOX are two major pollutants generated by diesel engines. Modern diesel aftertreatment systems include selective catalytic reduction (SCR) technology that helps reduce tailpipe NOX emissions when coupled with diesel exhaust fluid (DEF/urea) injection. However, this process also results in the formation of urea derived byproducts that can influence non-volatile particle number (PN) measurement conducted in accordance with the European Union (EU) Particle Measurement Program (PMP) protocol. In this program, an experimental investigation of the impact of DEF injection on tailpipe PN and its implications for PMP compliant measurements was conducted using a 2015 model year 6.7 L diesel engine equipped with a diesel oxidation catalyst, diesel particulate filter and SCR system. Open access to the engine controller was available to manually override select parameters. Ammonia-to-NOX (ANR) ratio was varied to understand the impact of urea injection rate on measured
Diesel engine exhaust poses an ongoing threat to human health as well as to the environment. Automotive exhaust treatment systems have been developed over the years to reduce the large amount of diesel particulate matter (DPM) released to the atmosphere. Current systems can be categorized as selective catalytic reduction, catalytic converters, and diesel particulate filters. This study presents an emission system that focuses on the removal of exhaust particles using Brownian diffusion of DPM toward fog drops followed by cyclonic separation of DPM rich fog drops. The experimental system consisted of a 13.2 kW diesel engine, heat exchanger to cool the exhaust to saturation temperature, ultrasonic fogger, cyclone separator, and recovery of waste particulate. Representative emission tests have been performed at five different diesel engine speeds and corresponding crankshaft loads. The scavenging coefficient as measured by the particle number concentration is 0.4-0.65 without fog and 0.6
Diesel engines are the primary power source for the medium and heavy-duty truck applications in the US. There is a wide range of regulatory developments being considered in the US that would impact the field of diesel engines and aftertreatment systems, such as the California Air Resources Board’s (CARB) low NOX standards and the extended durability requirement for aftertreatment systems. The proposed durability standards would require manufacturers to develop aftertreatment systems targeting up to 800,000 miles of full useful life (FUL) for Heavy heavy-duty (HHD) Application. Robust design and validation of aftertreatment systems is critical to ensure compliance with such stringent regulations. Several methodologies are being considered by the regulatory agencies for the compliance validation process, including the option of accelerated aging of the aftertreatment systems for a portion of the FUL. Performing FUL aging on an engine platform can be both technically challenging and
In North America, heavy-duty diesel engines for on-road use have to meet strict regulations for their emissions of nitric oxide and nitrogen dioxide (cumulatively referred to as ‘NOx’) besides other criteria pollutants. Over the next decade, regulations for NOx emissions are expected to becoming more stringent in North America. One of the major technical barriers for achieving in-use NOx emissions commensurate with the levels determined from in-laboratory test procedures required by regulations is controlling NOx emissions during cold start and engine idling. Since the exhaust gas temperature can be low during these conditions, the effectiveness of the exhaust after-treatment (EAT) system may be reduced. Under colder climate conditions like in Canada, the impact may be even more significant. In the experimental study of this paper, certain engine operation parameters such as the fuel injection timing, fuel injection frequency per cycle, engine speed, and exhaust gas recirculation (EGR
This specification describes a method and acceptance criteria for testing automotive wire harness retainer clips. Retainer clips are plastic parts that hold a wire harness or electrical connector in a specific position. Typical plastic retainers work by having a set of “branches” that can be inserted into a hole sized to be easy to install but provide acceptable retention. This specification tests retainer clips for mechanical retention when exposed to the mechanical and environmental stresses typically found in automotive applications over a 15-year service life. This specification has several test options to allow the test to match to the expected service conditions. The variability of applications typically arises from different ambient temperatures near the clip, different proximity to automotive fluids, different exposure to standing water or water spray, and different thicknesses of the holes that the clip is inserted into. Clips are typically inserted into sheet or rolled metal
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