Browse Topic: Exhaust pipes

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Novel Exhaust system architecture for Petroleum Oil Tanker Application vehicle2024-26-034501/16/2024
A large amount of heat given off by ATS on BS-VI exhaust system vehicle. Heat shield is required to protect the surrounding components. As per PESO (Petroleum and Explosives safety organization) guidelines for POL Application vehicle is that,(i)the surrounding temperature should not be more than 180° C and (ii) there is no spillage of any petroleum product to the bare surface of exhaust part directly. In BS-VI vehicle the heat given off from ATS is higher than the BS-IV vehicle. Typically flexible or wrap around heat shield is provided over ATS. In BS-VI flexible heat shield is not possible as more sensors and components are coming. In this project the novel design of heat shield (combination of flexible and metallic sandwich) on exhaust system is used. This design ensures the surrounding temperature is below 180° C and there is no spillage of petroleum product to the bare surface of exhaust parts (Including Tail pipe, Exhaust main pipe and ATS) directly. Also this design protect the
Sahoo, Rajanikanta, Khandagale, Anup, Manoharan, Logeshwaran, Kumar, Pravin
Computational flow dynamic analysis of particulate matter sensor for heavy duty commercial application2024-26-031201/16/2024
The Particulate Matter (PM) sensor is an exhaust sensor which measures cumulative particulate mass used for on-board diagnostics (OBD). It is used to monitor the filtration efficiency of diesel particulate filter (DPF) and helps detect leakage in DPF in exhaust system of diesel-engine vehicle. PM sensor is used in BS-6 phase-2 application as per the legislative requirement of monitoring the DPF for on-board diagnostic (OBD) purpose. As probe is in continuance of exhaust gases from exhaust pipe. Therefore an installation of PM sensor in exhaust system requires an evaluation in CFD to determine the tip velocity on the sensors and thermal mapping on the probe to evaluate its functioning exquisitely. With accurate result of exhaust gas flow, thermal mapping and sensor probe tip velocity, optimum position of sensor can be determined. It also avoids the physical iterations for mounting and thermal analysis of the sensor.
Fursule, Aishwarya Ravindra
Exhaust Noise Development Based on System Model2022-01-073603/29/2022
Exhaust noise performance has been developed using vehicle. Recently, the demand on reducing vehicles and untact development is increasing. In this study, the method for developing exhasut noise using system models was researched. The exhaust noise can be estimated using engine sound source and exhaust system's transfer functions. We measured engine sound source strength and exhaust system's insertion loss in experimental approach. We drew the theoretical equation leading to tail pipe noise with 2 systems' inherent property and considering connection point conditions such as impedences. We compared the estimated noise with measured using several vehicles. We concluded this approach is helpful for qualitative evaluation for the developing vehicle's exhaust noise without making vehicles. After estimating exhaust noise, we can set the system's target to meet the vehicle's target. Using this approach, it is expected that the exhaust noise can be estimated in advance of manufacturing
Park, Sangyoung
Performance Optimization of an Exhaust System for 4 Cylinder Engine by Implementation of Computational Fluid Dynamics, Acoustic and Thermal Analysis2022-01-076503/29/2022
The engine system requirements have changed from being focused only on delivering engine power to now having to meet environmental emission standards. The exhaust system collects exhaust gases from the combustion cylinders, eliminates dangerous pollutants, decreases noise, and discharges the purified exhaust gases at a safe distance from the vehicle's occupants. Designs of lightweight models for exhausts were always aimed at using newer lighter materials. As the design of an exhaust is more or less fixed, this approach is hardly profitable anymore. The most important components of an exhaust system are the exhaust manifold, the catalytic converter, the muffler, the resonator and connecting all of them together are connecting exhaust pipes. In this paper, the optimization of the various elements of 4 cylinder 1.8L engine exhaust system is carried out with the help of analysis software ANSYS 19.2 workbench, by performing ‘Steady State Thermal Analysis’, ‘Acoustic Analysis’ and simulating
Aiyan, Mohammed, Sagar, S Sumanth, Raghav S, Sanjay
Design and Optimization of an SUV Engine Compartment Undershield based on Latin Hypercube Design Method and Multi-island Genetic Algorithm2022-01-020103/29/2022
Vehicle engine compartment thermal management performance ensures engine performance and reduces pollutant emissions, and a suitable temperature range in the engine compartment during vehicle operation is critical to reducing carbon emissions. The design of the engine compartment components affects the thermal fluid flow performance in the engine compartment, which in turn affects the engine compartment thermal management performance, so it is necessary to explore the optimization of engine compartment components. In this paper, based on the phenomenon that the engine compartment undershield of an SUV caused abnormally high temperature on the surface of the engine compartment parts due to design defects, the engine compartment was modeled and simulated by STAR-CCM+, and it was found that the undershield caused hot air flow back, which was not conducive to engine compartment heat dissipation, so the undershield needed to be redesigned. The shape of the undershield was redesigned and
Liu, Yong
Performance Optimisation of an Exhaust System for 4 Cylinder Engine by Implementation of Computational Fluid Dynamics, Acoustic and Thermal Analysis2022-01-067703/29/2022
The engine system requirements have changed from being focused only on delivering engine power to now having to meet environmental emission standards. The exhaust system collects exhaust gases from the combustion cylinders, eliminates dangerous pollutants, decreases noise, and discharges the purified exhaust gases at a safe distance from the vehicle's occupants. Designs of lightweight models for exhausts were always aimed at using newer lighter materials. As the design of an exhaust is more or less fixed, this approach is hardly profitable anymore. The most important components of an exhaust system are the exhaust manifold, the catalytic converter, the muffler, the resonator and connecting all of them together are connecting exhaust pipes. In this paper, the optimization of the various elements of 4 cylinder 1.8L engine exhaust system is carried out with the help of analysis software ANSYS 19.2 workbench, by performing ‘Steady State Thermal Analysis’, ‘Acoustic Analysis’ and simulating
Aiyan, Mohammed, Raghav S, Sanjay, Sagar, S Sumanth
Tailpipe emission study of aged after treatment system on Medium duty commercial vehicle2021-26-021509/22/2021
As the emission norms are getting stringent in BSVI and regulations like OBD-II on vehicle. It is essential to define the life of exhaust after treatment along with the vehicle. The After treatment mainly consist DOC+DPF+SCR. Lubricating oil consumption is always be there with engine running condition and these additive oils contains phosphorus or zinc which gives an adverse effect on DOC and there is unburnt hydrocarbon (UNHBC), SOF in tail pipe that get accumulated in DPF which further require regeneration means a higher temperatures in exhaust after treatment (EATS ) and as the regeneration count increases there is ash accumulation in DPF that reduces its capability for soot accumulation. The tail pipe emission also consist Sulphur which has a negative impact on SCR for Nox conversion. So in present study we analyze the effect of (1) Chemical aging (2) Thermal aging on 3.77 liter diesel engine after treatment. A test cycle was prepared to run durability for EATS which consist total
Tiwari, Amit, Durve, Anurag, Srinivasan, Pradhan, Barman, Jyotirmoy
DESIGN AND ANALYSIS OF A MUFFLER FOR ENGINE EXHAUST NOISE AND HEAT REDUCTION2021-28-012809/15/2021
Exhaust noise and heat from engines is one of component noise pollution to the environment. Exhaust systems are developed to attenuate noise meeting required db levels and sound quality, emissions based on environment norms. Mufflers are important part of engine system and commonly used in exhaust system to minimize sound transmissions caused by exhaust gases and reduction of heat. Attaching a muffler in the exhaust pipe is the most effective means of reducing noise and heat. The aim of our project is to design and analyse a muffler for engine exhaust noise reduction. The suitable design and development will help to reduce the noise level and heat level, but at the same time the performance of the engine should not be hampered by the backpressure caused by the muffler. In this analysis 3D models are constructed using Solid Works software before exporting to ANSYS FLUENT CFD software for analysis. At ANSYS/FLUENT, pressure conditions will be specified as the inlet and outlet boundary
Deepan Kumar, Sadhasivam, Praveenkumar, Nagarajan, S, Arulkumar, N, Boopalan, PRAVEENKUMAR, S
A Study of the Effect of Light-Off Temperatures and Light-Off Curve Shape on the Cumulative Emissions Performance of 3-Way Catalytic Converters2021-01-059404/06/2021
The results of this paper will show the reader how to quantify a minimum light-off temperature to meet the required emissions standards with the use of a 3-way catalytic converter. The method can be applied to both motorcycle and larger automotive catalysts to help meet their respective emissions standards (Euro 5/Euro 7). The ability to predict a light-off temperature for any catalyst at the beginning of the project saves both time and resource. With an emphasis on how the shape of the light-off curve affects the cumulative tailpipe emissions and how shape of the light-off curves change with the ageing process. Changes in the light-off curves will be reviewed to understand how the chemical reactions and pore diffusion mechanisms within the catalyst deplete to negatively affect performance over its life time. Using the total cumulative emissions target to achieve the OBD (On Board diagnostic) requirement along with WMTC data, light-off curves were modelled using predicted catalyst
Mc Grane, Liam, Douglas, Roy, Irwin, Kurtis, Stewart, Jonathan, Woods, Andrew, Muehlstaedt, Fabian
Numerical Analysis and Modeling for the Exhaust Pulsating Flow around a Prism Inserted in a Pipe2021-01-060304/06/2021
For the measurements of flow rate, pressure and/or temperature in an engine exhaust pipe, probes are often inserted into the exhaust pipe depending on the application. These measurement probes differ a lot in terms of their size and shape. The flow around the probes become further complicated due to the pulsation of engine exhaust flow. In this study, computational fluid dynamics (CFD) simulations were carried out and a zero-dimensional (0D) model was constructed to analyze the flow field around the probe and flow rate of a pulsating flow. The simulations and the measurements of the flow rate and pressure were performed on flows around a hexagonal prism inserted in a circular pipe which is intended to be a differential pressure flow meter. The velocity field was also measured using the particle image velocimetry (PIV) technique. The CFD simulation results were validated with the experiments for both steady and pulsating flows. In the 0D model for pulsating flow, the flow acceleration
Iseki, Hirotaka, Nagaoka, Makoto, Yokoi, Shuntaro, Horibe, Naoto, Kawanabe, Hiroshi
On the Effects of Urea and Water Injection on Particles across the SCR Catalyst in a Heavy - Duty Euro VI Diesel Engine2020-01-219609/15/2020
Particle emissions from heavy-duty engines are regulated both by mass and number by Euro VI regulation. Understanding the evolution of particle size and number from the exhaust valve to the tail pipe is of vital importance to expand the possibilities of particle reduction. In this study, experiments were carried out on a heavy-duty Euro VI engine after-treatment system consisting of diesel oxidation catalyst, diesel particulate filter and selective catalytic reduction (SCR) unit with AdBlue injection followed by ammonia slip catalyst. The present work focusses on the SCR unit with regard to total particle number with and without nucleation particles both. Experiments were conducted by varying the AdBlue injection quantity, SCR inlet temperature [to vary the reaction temperature], exhaust mass flow rate [to vary the residence time in SCR], and fuel injection pressures [to vary inlet particle number and inlet NOx]. Sampling for particle measurements was performed at the inlet, upstream
K, Arun Prasath, Bernemyr, Hanna, Erlandsson, Anders
Unsteady Simulation of Six-Inlet Pulsed-Flow Turbocharger Turbine2020-01-223709/15/2020
The turbochargers are driven by unsteady, pulsating flow. Such flow is generated by the exhaust phase of an internal combustion engine (ICE). A lot of turbocharger simulations are done during steady-state operation. Such simulations are favorable for turbocharger optimization at a certain operating point. However, the frequency and amplitude of exhaust pulses can heavily influence turbine performance. This paper presents the results of the three-dimensional (3-D) simulations of the six-inlet turbocharger turbine, under pulsating operation with a moving mesh approach. One of the key points of interest was the separation of the pressure pulses from the six-exhaust pipes during engine operation. The leakage between the exhaust pipes was analyzed at each time step at the different turbine speed. Another key point was the turbine response during pulsating flow at the different rotor speed. Parameter such as the turbine total-static efficiency under the single-pressure pulse was investigated
Kozak, Dariusz, Mazuro, Paweł
Tesla's Cybertruck is audaciously austenitic20AUTP06_0306/01/2020
A proprietary 301-series stainless steel gives Tesla's first pickup truck unique sales attributes while saving tooling cost. Not since Ford's epic switch to aluminum for its F-Series body structures has an automaker's materials strategy created such a buzz. Tesla's decision to use stainless steel for its upcoming Cybertruck, as part of what CEO Elon Musk calls an “exoskeletal” architecture, aims to give the new electric pickup strength and durability beyond that of its competitors. The vehicle is slated to enter production in late 2021. Musk described the corrosion-resistant, 3-mm-thick (.118-in) sheet specified for Cybertruck as “ultra-hard 30X cold-rolled stainless-steel,” indicating an alloy variant developed from 300-series stainless steel. This popular class was used by DeLorean (304 alloy) in its roughly 10,000 DMC-12 sports cars, and by heavy-truck maker Autocar (302 alloy) in a small-volume run in the 1960s. During the same period Ford also experimented with a few stainless
Brooke, Lindsay
Relevance of Exhaust Aftertreatment System Degradation for EU7 Gasoline Engine Applications2020-01-038204/14/2020
Exhaust aftertreatment systems must function sufficiently over the full useful life of a vehicle. In Europe this is currently defined as 160.000 km. With the introduction of Euro 7 it is expected that the required mileage will be extended to 240.000 km. This will then be consistent with the US legislation. In order to quantify the emission impact of exhaust system degradation, an Euro 7 exhaust aftertreatment system is aged by different accelerated approaches: application of the Standard Bench Cycle, the ZDAKW cycle, a novel ash loading method and borderline aging. The results depict the impact of oil ash on the oxygen storage capacity. For tailpipe emissions, the maximum peak temperatures are the dominant aging factor. The cold start performance is effected by both, thermal degradation and ash accumulation. An evaluation of this emission increase requires appropriate benchmarks. For this purpose, an analysis of the emission impacts of ambient temperatures, driving modes and
Sterlepper, Stefan, Claßen, Johannes, Pischinger, Stefan, Görgen, Michael, Cox, Jim, Nijs, Martin, Scharf, Johannes
Ammonia Measurement Investigation Using Quantum Cascade Laser and Two Different Fourier Transform Infrared Spectroscopy Methods2020-01-036504/14/2020
Most diesel engine exhausts have been fitted with SCR (Selective Catalyst Reduction) in order to reduce NOX (Oxides of Nitrogen) by using NH3 (ammonia). However, both NOX and NH3 have been classified as compounds hazardous for the environment and human health. If the reaction between NOX and NH3 is unbalanced during treatment, it can lead to either NOX or NH3 being released into the environment. Accurate measurement is thus necessary. QCL (Quantum Cascade Laser) and FTIR (Fourier Transform InfraRed) are two methods that have been used to measure NH3 and NOX directly in diesel engine exhausts. However, only a few studies have compared those two methods of NH3 measurement, mainly from diesel engine exhausts. The aim of this paper is to compare the QCL and 2 different FTIR specifications for NH3 measurement directly from diesel engine exhausts under well-controlled laboratory conditions. Researchers have found that as NH3 is reactive, it is absorbed inside the exhaust pipe if the probe
Li, Nilton, El-Hamalawi, Ashraf, Barrett, Richard, Baxter, Jim
Real-World Emission Analysis Methods Using Sensor-Based Emission Measurement System2020-01-038104/14/2020
Every year, exhaust gas regulations are getting stricter with the intention to solve the average air pollution problem, however, local roadside pollution is still a pressing issue. In order to solve this local roadside pollution problem, it is necessary to evaluate and/or predict “where” and “how much” pollutants such as NOx are emitted. To predict the local roadside pollution, it is necessary to collect emissions data from various kinds of vehicles driving on real-world and analyze them. In recent years, Real Driving Emission regulations using PEMS (Portable Emission Measurement System) have been introduced mainly in Europe. A typical PEMS configuration can weigh close to 100 kg however, and its weight affects the driving conditions of vehicles running on actual roads. In this study, we focused on the analysis of real-world emissions using SEMS (Sensor-based Emission Measurement System). Whereas PEMS is a method of sampling and analyzing exhaust gas, SEMS directly attaches a NOx
Sato, Susumu, Abe, Seiya, Himeno, Ryo, Nagasawa, Tsuyoshi, Kosaka, Hidenori, Tanaka, Kotaro, Tange, Takeshi
Experimental Study of Acoustic and Thermal Performance of Sound Absorbers with Microperforated Aluminum Foil2019-01-158006/05/2019
Aluminum foil applied to the surface of sound absorbing materials has broad application in the automotive industry. A foil layer offers thermal insulation for components close to exhaust pipes, turbo chargers, and other heat sources in the engine compartment and underbody. It can also add physical protection for acoustic parts in water-splash or stone-impingement areas of the vehicle exterior. It is known that adding impermeable plain foil will impact the sound absorption negatively, so Microperforated Aluminum Foil (MPAF) is widely used to counteract this effect. Acoustic characteristics of MPAF can be modeled analytically, but deviation of perforation size and shape, variation of hole density, material compression, and adhesive applied to the back of the foil for the molding process can impact the acoustic and thermal insulation performance. Because we cannot rely on analytical tools to generate accurate performance of these materials in a production environment, this paper will
Yin, Gang Glenn, Parrett, Alan, Salazar Prieto, Felipe G., Roggenkamp, Timothy J.
Development and Experimental Validation of a Control Oriented Model of a Catalytic DPF2019-01-098504/02/2019
1 The wall-flow Diesel Particulate Filter (DPF) is currently the most common after-treatment system used to meet the particulate emissions regulations for automotive engines. Today’s technology shows the best balance between filtration efficiency and back-pressure in the engine exhaust pipe. During the accumulation phase the pressure drop across the filter increases, thus requiring periodic regeneration of the DPF through after and post fuel injection strategies. This paper deals with the development of a control oriented model of a catalytic silicon carbide (SiC) wall flow DPFs with CuFe2O4 loading for automotive Diesel engines. The model is intended to be used for the real-time management of the regeneration process, depending on back-pressure and thermal state. In order to ensure suitable computational demand and to realize emissions control and fuel economy objectives, the 0-D model has been developed with the aim of investigating the essential behavior of the system, such as the
D'Aniello, Federica, Rossomando, Bruno, Arsie, Ivan, Pianese, Cesare
Agglomeration and Nucleation of Non-Volatile Particles in a Particle Grouping Exhaust Pipe of a Euro VI Heavy-Duty Diesel Engine2019-01-004401/15/2019
The possibility of non-volatile particle agglomeration in engine exhaust was experimentally examined in a Euro VI heavy duty engine using a variable cross section agglomeration pipe, insulated and double walled for minimal thermophoresis. The agglomeration pipe was located between the turbocharger and the exhaust treatment devices. Sampling was made across the pipe and along the centre-line of the agglomeration pipe. The performance of the agglomeration pipe was compared with an equivalent insulated straight pipe. The non-volatile total particle number and size distribution were investigated. Particle number measurements were conducted according to the guidelines from the Particle Measurement Programme. The Engine was fuelled with commercially available low sulphur S10 diesel. Experiments conducted in heavy duty engine relevant operating points were done to sweep the effect of (i) Mass flow rate in the exhaust (ii) Temperature in the exhaust and (iii) Engine speed and thus exhaust
K, Arun Prasath, Stenlaas, Ola, Bernemyr, Hanna, Erlandsson, Anders
Water Load Determination Approach in Two Wheeler Exhaust System2018-32-007510/30/2018
Future emission norms in India (BS6) necessitates the 2 wheeler industry to work towards emission optimization measures. Engine operation at stoichiometric Air-Fuel Ratio (AFR) would result in a good performance, durability and least emissions. To keep the AFR close to stoichiometric condition, an Oxygen sensor is placed in the exhaust system, which detects if air-fuel mixture is rich (λ<1) or lean (λ>1) and provides feedback to fuel injection system for suitable fuel control. O2 sensor has a ceramic element, which needs to be heated to a working temperature for its functioning. The ceramic element would break (thermal shock) if water in liquid form comes in contact with it when the element is hot. To counter this, oxygen sensor is either fully heated only when all the water in the exhaust system is evaporated, which results in delayed closed loop control, or is capable to withstand higher amount of water in the exhaust system by for example being applied with thermal shock protection
Meena, Ranjana Kumari, Krusch, Andrea, Meister, Konrad, Holzknecht, Christopher
Nonlinear Acoustic Analysis of Loudspeakers in the Exhaust Dynamic Sound Technology2018-01-155906/13/2018
An ongoing trend among automotive exhaust suppliers is the application of loudspeakers in their systems to tailor the exhaust sound to the customers’ needs. In addition to it, undesirable engine order noise can be cancelled by a closed loop control system. Due to the high sound pressure from the engine, the loudspeaker is often required to run at its power maximum. A higher input power eventually causes a nonlinear behavior, resulting in undesirable sound pressure level or harmonic distortion. Thus, the understanding of nonlinear behavior of loudspeakers and the recognition of dominant effects are required. This paper presents the main nonlinearities of loudspeakers and the comparison of theories on linear and non-linear loudspeaker models. For validation of the model, one loudspeaker enclosure and one typical exhaust system with a loudspeaker have been calculated. Ultimately it was found that a nonlinear loudspeaker model would be essential for a precise tuning of active exhaust sound
Kim, Hoi-Jeon, Schultz, Bernhard
Feasibility Analysis of a Non-Intrusive Exhaust Energy Recovery System Based on the Use of Thermoelectrics2018-01-078004/03/2018
This paper presents a feasibility analysis of the use of a thermoelectric generator for the design of a non-intrusive exhaust energy recovery system. The energy recovery system is intended to be used on a light duty vehicle with naturally aspirated internal combustion engine. The non-intrusive characteristic is proposed as an exploratory work with the aim to develop an aftermarket system. The energy source for the system is the exhaust pipe wasted heat. The analysis includes as design variables the number of thermoelectric modules and their location along the exhaust system. The characteristics under analysis are fuel consumption and payload. A numerical model is developed and used to investigate the possible design scenarios. This model is composed by three sub-models. The sub models are mean value engine model, exhaust heat transfer model, and vehicle longitudinal dynamics model. Three driving cycles are used: two standard driving cycles and a real driving cycle. Two commercial
Gomez Herrera, Jorge David, Munoz, Luis
The Measures of Improving Power Generation Stability for Harvesting Automobile Exhaust Energy2018-01-136704/03/2018
The automobile exhaust energy can be recovered by the thermoelectric module generator(TEG). Owing to the complex urban traffic, the exhaust gas’s temperature fluctuations are resulted, which means the unstable hot-end temperature of the TEG. By installing solid heat capacity material(SHCM) to the area between the outer wall of the exhaust pipe and the TEG, it is possible to appropriately reduce the temperature fluctuation, but there is still a fluctuation of the TEG’s power output. Then by adding voltage filter circuit (VFC) after the TEG, the power output stability can be improved. This research uses SHCM and VFC to improve the stability of the exhaust gas generation. Firstly, the three-dimensional heat transfer model of the exhaust pipe thermoelectric power generation system is established. The heat capacity materials with low thermal resistance and high heat capacity were selected as the research object based on previous research. Secondly, the fluctuation relationship of the
Wang, Zongsong, Tan, Gangfeng, Xiao, Longjie, Huang, Miaohua, Yu, Houyu, Wang, Yishi, Quan, Jiakang, Huang, Shiping
High-Performance Rear- and Mid-Engine Vehicle Exhaust System Temperatures2018-01-143604/03/2018
Hot surface ignition of combustible material is a known cause of vehicle fires. Although the detailed mechanisms of hot surface ignition are highly complex, the surface temperature is known to play a crucial role in this process. There has been limited previous work in the literature on this topic, much of which has focused on engine or exhaust system surface temperatures of the most common types of passenger vehicles. Also, much of this work was done in an unrepeatable manner and suffered from measurement technique induced errors. The focus of the present work is on repeatable and low measurement technique induced error temperature measurements of exhaust system surface temperatures of rear- and mid-engine sports cars. Temperature measurements were made at several points along the exhaust systems of vehicles both with and without turbo chargers on a 5-mile oval track. The exhaust system surface temperatures were examined under conditions of transient acceleration and steady-state
Papageorge, Michael, Colwell, Jeff
The Application of Solid Selective Catalytic Reduction on Heavy-Duty Diesel Engine2017-01-236410/08/2017
Urea SCR technology is the most promising technique to reduce NOx emissions from heavy duty diesel engines. 32.5wt% aqueous urea solution is widely used as ammonia storage species for the urea SCR process. The thermolysis and hydrolysis of urea produces reducing agent ammonia and reduces NOx emissions to nitrogen and water. However, the application of urea SCR technology has many challenges at low temperature conditions, such as deposits formation in the exhaust pipe, lack deNOx performance at low temperature and freezing below -12°C. For preventing deposits formation, aqueous urea solution is hardly injected into exhaust gas stream at temperature below 200°C. The aqueous urea solution used as reducing agent precursor is the main obstacle for achieving high deNOx performances at low temperature conditions. This paper presents a solid SCR technology for control NOx emissions from heavy duty diesel engines. The solid SCR technology, using a solid metal ammine complex to store ammonia
Li, Jiaqiang, Ge, Yunshan, He, Chao, Tan, Jianwei, Peng, Zihang, Li, Zidi, Chen, Wei, Wang, Shijie
An Investigation of the Transient DPF Pressure Drop under Cold Start Conditions in Diesel Engines2017-01-237210/08/2017
To monitor emission-related components/systems and to evaluate the presence of malfunctioning or failures that can affect emissions, current diesel engine regulations require the use of on-board diagnostics (OBD). For diesel particulate filters (DPF), the pressure drop across the DPF is monitored by the OBD as the pressure drop is approximately linear related to the soot mass deposited in a filter. However, sudden acceleration may cause a sudden decrease in DPF pressure drop under cold start conditions. This appears to be caused by water that has condensed in the exhaust pipe, but no detailed mechanism for this decrease has been established. The present study developed an experimental apparatus that reproduces rapid increases of the exhaust gas flow under cold start conditions and enables independent control of the amount of water as well as the gas flow rate supplied to the DPF. The results show that the sudden decrease in the DPF pressure drop is caused by the water in the developed
Kobashi, Yoshimitsu, Oooka, Shun, Jiang, Lin, Goto, Jun, Ogawa, Hideyuki, Shibata, Gen
DMADV Approach for Engineering Optimization and Quality - Application and Adaptability in Indian Automobile Industry2017-28-193007/10/2017
Indian Automobile Industry has started using Six Sigma for Vehicle Design and process improvement to compete with Global competition. This Paper describes how the Tools of Six Sigma shall be used as an Effective Tool for both redefining the Design and the Process Improvement. This Paper talks on the evolution of DMADV approach in Indian Automobile Industry compared to the related Trends in Other Manufacturing Sectors. The Author describes how the warranty failures in Commercial Segment Vehicle Category which was the selling talk for the Competition was addressed in Leading Indian Automobile OEM. As this Failure was adversely impacting customer satisfaction and no solution seemed forthcoming, top Management indicated to use a radically different approach to solve the problem within a years’ time. Among the different processes evaluated, DMADV six sigma approach brought in a creative approach to problem solving and improved systematic team work between the supplier, manufacturing
Jaswal, Anil Kumar, Chandrasekaran, Pradeep, Ramadoss, Surendran
Analysis of the Effect of Intake Plenum Design on the Scavenging Process in a 2-Stroke Boosted Uniflow Scavenged Direct Injection Gasoline (BUSDIG) Engine2017-01-103103/28/2017
In this study, the effect of the intake plenum design on the scavenging process in a newly proposed 2-stroke Boosted Uniflow Scavenged Direct Injection Gasoline (BUSDIG) engine was studied in detail by three dimensional (3D) computational fluid dynamics (CFD) simulations. In the BUSDIG engine, the intake scavenge ports are integrated into the cylinder liner and their opening and closure are controlled by the movement of piston top while exhaust valves are placed in the cylinder head. In order to accommodate the optimized scavenge ports in the real engine application, the intake plenum with an inlet pipe and a scavenge chamber was designed and connected to the 12 evenly distributed scavenge ports in a single cylinder BUSDIG engine. In order to achieve optimal scavenge performances and sufficient in-cylinder flow motions to enhance the fuel/air mixing, five design parameters of the intake plenum were investigated, including the ratio of the inlet area relative to the scavenge port area
Wang, Xinyan, Ma, Jun, Zhao, Hua
The TEG Hot-End Heat Capacity’s Effect on the Power Output Stability for Harvesting Automobile Exhaust Energy2017-01-016003/28/2017
While the car ownership increasing all over the world, the unutilized thermal energy in automobile exhaust system is gradually being realized and valued by researchers around the world for better driving energy efficiency. For the unexpected urban traffic, the frequent start and stop processes as well as the acceleration and deceleration lead to the temperature fluctuation of the exhaust gas, which means the unstable hot-end temperature of the thermoelectric module generator (TEG). By arranging the heat conduction oil circulation at the hot end, the hot-end temperature’s fluctuation of the TEG can be effectively reduced, at the expense of larger system size and additional energy supply for the circulation. This research improves the TEG hot-end temperature stability by installing solid heat capacity material(SHCM) to the area between the outer wall of the exhaust pipe and the TEG, which has the merits of simple structure, none energy consumption and light weight. Firstly, the exhaust
Xiao, Longjie, He, Tianming, Tan, Gangfeng, Huang, Bo, Ping, Xianyao
Quantitative Analysis of Low Pressure-Driven Spray Mass Distribution and Liquid Entrainment for SCR Application through a Mechanical Patternator2017-01-096503/28/2017
The application of liquid aqueous Urea Solution (AUS) as reductant in SCR exhaust after-treatment systems is now a commonly accepted industry standard. Unfortunately, less acceptable are the associated difficulties caused by incomplete decomposition of the liquid, resulting in solid deposits which accumulate in the exhaust pipe downstream of the dosing components. The correct prediction of the spray pattern and, therefore, the spray impact on the walls is a key feature for the system optimization. A mechanical patternator, designed on the basis of CFD performance assessment, involving a Lagrangian representation of the dispersed liquid fully coupled with a 3D Eulerian description of the carrier phase, has been built and used to measure the spray mass distribution. The effect of the droplets generated from the interaction among spray, probes and contingent liquid film is taken into account in the geometrical definition of the shape and the position of the patternator, as well as the
Nocivelli, Lorenzo, Montenegro, Gianluca, Onorati, Angelo, Curto, Francesco, Dimopoulos Eggenschwiler, Panayotis, Liao, Yujun, Vogel, Alexander
Field Failure Resolution of a Tractor Engine Exhaust System Using Constrained Single Objective Optimization and Stochastic Analysis2017-26-023301/10/2017
The tractor engine related mounting brackets are very critical due to different aspects of vehicle performance, durability and noise. These mounting bracket have been designed as a framework to support engine external parts like muffler, exhaust tail pipe, alternator etc. Vibration and fatigue has been continuously a concern which may lead to structural failure and performance issues. Various such failures are faced regularly by automotive industry and finite element based analysis are used to resolve them. The resolution is done by playing with the component thicknesses, material, by providing additional support etc. However, due to large degree of uncertainty associated with the loading, boundary conditions, manufacturing, environmental effects; still there is some probability of failure. This paper focuses on a field failure issue of an exhaust system of a tractor and subsequent concern resolution. Multiple field failures like Under Hood Muffler (UHM) lug failure and UHM mounting
Perumal, Solairaj, Kumar, Abhay, Mahajan, Arun, Redkar, Dinesh, Balakrishnan, Sureshkumar
Powertrain Mounted Exhaust System Failure Correlation and Methodology Development in CAE2017-26-026701/10/2017
Exhaust system is one of the complex automotive systems in terms of performance and strength prediction due to combination of transient mechanical and thermal loads acting on it simultaneously. Traditionally, most of automotive vehicles have exhaust systems with hot end mounted on engine and cold end mounted on chassis or BIW through hangers. A new powertrain mounted exhaust system was developed in-house. This exhaust system underwent validation and evaluation during development phase. Durability concerns were observed on exhaust system in Track test and gear shift durability test. This paper focuses on identifying the root cause of these concerns based on the failures observed during evaluation in Accelerated Durability (ADT) and gear shift durability (GSD) tests. Based on the architecture and packaging space challenges in vehicle, engine is mounted on two mounts and a roll restrictor. Muffler, which has higher inertia, is mounted at higher offset with respect to engine rolling axis
Mohapatra, Durga Prasad, Kangde, Suhas, Londhe, Abhijit, Srikanth, N N, Singh, Pravin
Fast Exhaust Nephelometer (FEN): A New Instrument for Measuring Cycle-Resolved Engine Particulate Emission2016-01-232910/17/2016
Soot emissions from direct-injection engines are sensitive to the fuel-air mixing process, and may vary between combustion cycles due to turbulence and injector variability. Conventional exhaust emissions measurements cannot resolve inter- or intra-cycle variations in particle emissions, which can be important during transient engine operations where a few cycles can disproportionately affect the total exhaust soot. The Fast Exhaust Nephelometer (FEN) is introduced here to use light scattering to measure particulate matter concentration and size near the exhaust port of an engine with a time resolution of better than one millisecond. The FEN operates at atmospheric pressure, sampling near the engine exhaust port and uses a laser diode to illuminate a small measurement volume. The scattered light is focused on two amplified photodiodes. Proof-of-concept tests were conducted on a heavy-duty single-cylinder research engine using a Westport high-pressure direct-injection (HPDI) natural gas
Kheirkhah, Pooyan, Kirchen, Patrick, Rogak, Steven
Investigation of Urea Derived Deposits Composition in SCR Systems2016-01-232710/17/2016
Ideally, complete decomposition of urea should produce only two products in active Selective Catalytic Reduction (SCR) systems: ammonia and carbon dioxide. In reality, urea decomposition reaction is a two-step process that includes the formation of ammonia and isocyanic acid as intermediate products via thermolysis. Being highly reactive, isocyanic acid can initiate the formation of larger molecular weight compounds such as cyanuric acid (CYN), biuret (BIU), melamine (MEL), ammeline (AML), ammelide (AMD), and dicyandimide (DICY). These compounds can be responsible for the formation of deposits on the walls of the decomposition reactor in urea SCR systems. Composition of these deposits varies with temperature exposure, and under certain conditions can create oligomers that are difficult to remove from exhaust pipes. Deposits can affect efficiency of the urea decomposition, and if large enough, can inhibit the exhaust flow and negatively impact ammonia distribution on the SCR catalyst
Eakle, Scott, Kroll, Svitlana, Henry, Cary
Performance Characteristics of an Ammonia-Water Absorption Refrigeration System Driven by Diesel Waste Exhaust Heat2016-01-066404/05/2016
The thermal performance of an ammonia-water-hydrogen absorption refrigeration system using the waste exhaust gases of an internal combustion diesel engine as energy source was investigated experimentally. An automotive engine was tested in a bench test dynamometer, with the absorption refrigeration system adapted to the exhaust pipe via a heat exchanger. The engine was tested for different torques (15 N.m, 30 N.m, and 45 N.m). The exhaust gas flow to the heat exchanger built on the generator was controlled manually using two control valves. The refrigerator reached a steady state temperature between 10 and 14.5°C about 3.5 hours after system start up, depending on engine load. The maximum coefficient of performance was 0.10 obtained for the controlled exhaust mass flow case at torque 30 Nm after 3hrs from system startup.
Hassaneen, Ahmed E., Aly, Wael I. A., Bedair, Gamal, Abdussalam, Mohammed
Thermal Stability Research of Vehicle Exhaust Waste-Heat Recovery System with Intermediate Medium2016-01-022804/05/2016
Vehicle exhaust waste-heat recovery with thermoelectric power generators can improve energy efficiency, as well as vehicle fuel economy. In the conventional structure, the hot-end of thermoelectric module is directly connected with the outer wall of the exhaust pipe, while the cold-end is connected with the water pipe’s outer wall of the vehicle engine cooling cycle. However, the variety of vehicle engine operating conditions leads to the instability of the hot-end temperature, which will reduce the generating efficiency of the thermoelectric modules and also shorten its service life. This research is on the basis of constructing a heat transfer oil circulation, and to study the action principles and implementation methods of it. In this circulation, the heat transfer oil, as the intermediate medium, absorbs the exhaust waste heat and transfers the heat to the hot-end of the thermoelectric module steadily, which stabilizes the hot-end temperature under various vehicle engine operating
Han, Mengzuo, Tan, Gangfeng, Guo, Xuexun, Zhan, Ruobing, An, Xuyang, Xue, Weiye, Kang, HongBo
Optimization of Muffler Acoustics Performance using DFSS Approach2016-01-129204/05/2016
Noise pollution is a major concern for global automotive industries which propels engineers to evolve new methods to meet passenger comfort and regulatory requirements. The main purpose of an exhaust system in an automotive vehicle is to allow the passage of non-hazardous gases to the atmosphere and reduce the noise generated due to the engine pulsations. The objective of this paper is to propose a Design for Six Sigma (DFSS) approach followed to optimize the muffler for better acoustic performance without compromising on back pressure. Conventionally, muffler design has been an iterative process. It involves repetitive testing to arrive at an optimum design. Muffler has to be designed for better acoustics performance and reduced back pressure which complicates the design process even more. A hybrid type muffler is the most commonly used muffler in automotive industry and it plays an important role in noise attenuation by using a combination of impedance mismatch and absorption
Dixit, Manish, Sundaram, V, Kumar S, Sathish
A Novel Approach for Flow Simulation and Back Pressure Prediction of Cold End Exhaust System2016-28-023502/01/2016
The performance of any automotive engine depends not only upon its core engine parts but also on the effectiveness of the sub-systems attached to the engine, like the intake, fuel, engine cooling and exhaust systems. The exhaust system being a critical system of any automotive vehicle plays a responsible role of improving the ride quality of the vehicle and fuel economy. The effective design of exhaust system is critical in order to ensure the required exhaust gas is exited from the engine and at the same time the noise is attenuated. In this paper a novel approach is developed in order to characterize the flow through the cold end exhaust system and reduce the pressure drop to achieve desired performance. The exhaust system attenuates the noise from the engine without deteriorating the engine performance by ensuring an optimum value of exhaust back pressure. Exhaust back pressure is one of the crucial parameters that are always scrutinized by the automotive manufactures to ensure that
Dixit, Manish, Sundaram, V, Sathish Kumar, S.
Study of Pressure Losses of Unsteady Compressible Flows in Three- Way Junctions2015-24-239909/06/2015
The aim of this paper is to extend the evaluation of the accuracy of published 1-D pressure loss coefficients which are used in 1-D gas dynamics models, in unsteady compressible flows propagating in the exhaust pulses in manifolds. These pressure loss coefficients were derived from the conservation of linear momentum over finite control volumes based on assumptions including steady flow. The objectives of this work were to evaluate the accuracy of the pressure loss coefficients over the type of flows generated by engine-like pressure pulses propagating in a range of three-pipe junctions. The evaluation was performed by reference to results from unsteady, compressible, 3-D Reynolds-averaged computational fluid dynamic (CFD - open source software OpenFOAM) simulations. Two of the junction branches represented the exhaust pipes from two cylinders and the remaining was the outlet pipe. All pipes had a diameter of 25mm with length ratio 1:2 between inlet and outlet. Y junctions of 30° and
Nikita, Christina, Hardalupas, Yannis, Taylor, Alexander
Prediction of Airborne Sound Transmission into the Passenger Compartment2015-01-226606/15/2015
Several of the exterior noise sources existing around a vehicle can cause airborne noise issues at relatively low frequencies. SEA, traditionally used for airborne sound issues is not suitable for the frequency range of interest. Finite Element analysis has been used. Handling of the non-reflecting condition on the outer boundary of the exterior cavity is an issue. Recently, advances have been made in several commercially available codes, which made the analysis practical. Including the poro-elastic material model for foam-based carpets is also becoming practically possible. The purpose of the current study is to investigate the practical applications of those new developments against test data, and to estimate the feasibility of using these procedures in the vehicle development projects. Measurements were carried out in a new semi-anechoic chamber at Volvo Cars. These measurements involved 3 body objects - a Body-in-Blue (BIB) sedan, a Complete Vehicle (CV) sedan and a CV wagon. The
Pietrzyk, Andrzej
The Predictive Simulation of Exhaust Pipe Narrow-band Noise2015-01-132904/14/2015
A method of predictive simulation of flow-induced noise using computational fluid dynamics has been developed. The goal for the developed method was application in the vehicle development process, and the target of the research was therefore set as balancing the realization of a practical level of predictive accuracy and a practical computation time. In order to simulate flow-induced noise, it is necessary to compute detailed eddy flows and changes in the density of the air. In the research discussed in this paper, the occurrence or non-occurrence of flow-induced noise was predicted by conducting unsteady compressible flow calculation using large eddy simulation, a type of turbulence model. The target flow-induced noise for prediction was narrow-band noise, a type of noise in which sound increases in specific frequency ranges. Assuming the area of generation of flow-induced noise to be the exhaust pipe, including the complex shape of the muffler, predictive accuracy was verified under
Kanai, Katsutomo, Katsuyama, Hideki
Thermoelectric Module Temperature Stability Control for the Vehicle Engine Exhaust Heat Recovery2015-01-035004/14/2015
The vehicle engine exhaust wastes heat. For the conventional scheme, the hot-end of the thermoelectric module is connected with the exhaust pipe, while the cold-end is cooled through the vehicle engine cooling cycle. The variation of vehicle engine operating conditions brings the instability of the hot-end temperature, which affects the power generation performance of thermoelectric materials and increases the damage risk to the thermoelectric materials caused by the high temperature. This research adopts the heat transfer oil circulation as the intermediate fluid to absorb the dynamic heat flux of the vehicle engine exhaust so as to release the heat steadily to the hot-end of the thermoelectric module. The thermal characteristics of the target diesel vehicle engine exhaust gas are evaluated based on the experimental data firstly. Then, the mathematical model of the thermoelectric evaporation system is built on the basis of the geometrical parameters and the specific vehicle engine
Li, Zhi, Tan, Gangfeng, Cai, Jing, Yang, Zhongjie, Wang, YiRui, Xu, Haobo
Advanced Spray Impingement Modelling for an Improved Prediction Accuracy of the Ammonia Homogenisation in SCR Systems2015-01-105404/14/2015
A fast preparation of the liquid urea water solution (UWS) is necessary to ensure high conversion rates in exhaust aftertreatment systems based on Selective Catalytic Reduction (SCR). Droplet wall interaction is of major importance during this process, in particular droplet breakup and the Leidenfrost effect. A deeper understanding of the underlying mechanisms is a basic requirement to calibrate CFD models in order to improve their prediction accuracy. This paper presents a detailed literature study and discussion about the major impact factors on droplet wall interaction. Measurements of the Leidenfrost temperature were conducted and the corresponding regimes classified based on optical observations. The pre- and post-impingement spray was analysed using the laser diffraction method. Further, the validity of spray initialisation based on measurements at room temperature was verified. The Leidenfrost effect, partial droplet evaporation, droplet breakup and evaporation at the catalyst
Smith, Henrik, Zöchbauer, Markus, Lauer, Thomas
Influence of Linear and Parabolic Elements in Structural Rigidity of Converter Mounting Brackets2015-01-132604/14/2015
Generation of discretization with prescribed element sizes are adapted to the geometry. From the rules of thumb, for a complicated geometry it is important to select the reasonable element order, shapes and size for accurate results. In order to that, this paper describes the influence of elemental algorithm of the catalytic converter mounting brackets. Brackets are main source of mounting of various systems mainly intake and exhaust in the engine. In hot end exhaust system, a bracket design plays a vital role because it has to withstand heavy structural vibrations without isolation combined with thermal loads. Bracket design and stiffness determines the whole catalytic converter system's rigidity. So, here discretization of converter brackets by linear and parabolic elements is studied with different elements types and compared. The study shows disparity in the structural accuracies of the brackets in each of elemental orders respect to the element shapes i.e. in the stiffness and
Rajadurai, Sivanandi, Mani, Guru Prasad, Raja, Kavin, Mohan, Sundaravadivelu
Simulation Study of Divided Exhaust Period for a Regulated Two-stage Downsized SI Engine2014-01-255010/13/2014
The Divided Exhaust Period (DEP) concept is an approach which has been proved to significantly reduce the averaged back pressure of turbocharged engines whilst still improving its combustion phasing. The standard layout of the DEP system comprises of two separately-functioned exhaust valves with one valve feeding the blow-down pulse to the turbine whilst the other valve targeting the scavenging behaviour by bypassing the turbine. Via combining the characteristics of both turbocharged engines and naturally aspirated engines, this method can provide large BSFC improvement. The DEP concept has only been applied to single-stage turbocharged engines so far. However, it in its basic form is in no way restricted to a single-stage system. This paper, for the first time, will apply DEP concept to a regulated two-stage (R2S) downsized SI engine. By controlling the timing of the exhaust valves separately to feed the exhaust mass flow to the high-pressure turbine or the low-pressure turbine or the
Hu, Bo, Brace, Chris, Akehurst, Sam, Copeland, Colin, Turner, J.W.G.
Cold-end Temperature Control Method for the Engine Exhaust Heat Thermoelectric Module2014-01-234309/30/2014
To make full use of engine exhaust heat and further improve the utilization of the energy efficiency of the heavy truck, thermoelectric module is used to contribute to thermoelectric power generation. The hot-end temperature of the module varies with the engine operating condition because it is connected with the exhaust pipe. The cold-end of the thermoelectric module is mainly cooled by engine cooling system. Increasing the temperature difference between the hot-end and cold-end of the thermoelectric module is a good way to improve the thermoelectric conversion efficiency. For the poor controllability of the hot-end temperature of the thermoelectric module, this study puts forward by lowering the cold-end temperature of the thermoelectric module so as to ensure the improvement of the thermoelectric conversion efficiency. The cooling circle for the cold-end of the thermoelectric module which is independent of the engine cooling system is built. The nucleate boiling flow is adopted to
Bai, Manfei, Tan, Gangfeng, Deng, Yadong, Wang, Wenying, Yan, Hui
Model Based Study of the Urea Injector's Effects on SCR of an 11 Liter Diesel Engine2014-01-155504/01/2014
Selective catalytic reduction (SCR) has become one of the primary technologies to reduce internal combustion engine (ICE) emission. The installation angle of urea injector plays an important role during the SCR process. The urea injector is often vertically mounted to the exhaust pipe for on road heavy duty truck because of its good performance and general packaging convenience, and this type of installation has been the focus of previous research. However, due to certain packaging constraints or responsiveness considerations, the injector is installed with an inclined acute angle to the exhaust pipe under some circumstance. To evaluate the underlying benefits and risks of this type of installation angle, a computational fluid dynamic (CFD) model based on the Renolds averaged Navier-Stokes (RANS) solver from AVL Fire is used to simulate the injection process of urea for an acute-angled 3-hole injector, through which, the urea spray's formation and motion, wallfilm accumulation and NH3
Sun, Wanyu, Wang, Shufen, Yan, Shanheng, Guo, Lei, Hou, Yuanjing
1-D Simulation Study of Divided Exhaust Period for a Highly Downsized Turbocharged SI Engine - Scavenge Valve Optimization2014-01-165604/01/2014
Fuel efficiency and torque performance are two major challenges for highly downsized turbocharged engines. However, the inherent characteristics of the turbocharged SI engine such as negative PMEP, knock sensitivity and poor transient performance significantly limit its maximum potential. Conventional ways of improving the problems above normally concentrate solely on the engine side or turbocharger side leaving the exhaust manifold in between ignored. This paper investigates this neglected area by highlighting a novel means of gas exchange process. Divided Exhaust Period (DEP) is an alternative way of accomplishing the gas exchange process in turbocharged engines. The DEP concept engine features two exhaust valves but with separated function. The blow-down valve acts like a traditional turbocharged exhaust valve to evacuate the first portion of the exhaust gas to the turbine. While the scavenge valve feeding the latter portion of the exhaust gas directly into the low resistant exhaust
Hu, Bo, Akehurst, Sam, Brace, Chris, Copeland, Colin, Turner, James
Comparative Study on Performance and Emission Characteristics of Fish Oil Biodiesel and Mahua Oil Biodiesel Blend with Diesel and Diesel Fuel in a Medium Capacity Compression Ignition Employing Urea-SCR with Cu-ZSM52014-01-149904/01/2014
The present world scenario faces a serious threat from increasing dependence on fossil fuels. This has triggered the awareness to find alternative energy as their sustainable energy sources. Biodiesel as a cleaner renewable fuel may be considered as a good substitution for diesel fuel due to it being used in any compression ignition engine without any modification. The main advantages of using biodiesel are its renewability and better quality of exhaust gas emissions. In terms of emissions from biodiesel, the cause of concern continues to be the NOx emissions. Therefore, to compliment the functioning of biodiesels, Urea-SCR over Cu-ZSM5 catalyst is an effective option due to its ability to convert NOx into nitrogen and water. There has been increasing concerns that biodiesel feedstock may compete with food supply in the long term. The recent paper focuses on use of two non-edible oils mahua oil and fish oil (processed from waste produced by fish). The acid number of fish oil was found
Sharma, Shubham, Gupta, Sahil, Kumar, Naveen, Kumar, Sidhant
Study of an EGR System for Downsizing Turbocharged Gasoline Engine to Improve Fuel Economy2014-01-119904/01/2014
This paper presents a study of a cooled exhaust gas recirculation (EGR) system applied to a turbocharged gasoline engine for improving fuel economy. The use of a higher compression ratio and further engine downsizing have been examined in recent years as ways of improving the fuel efficiency of turbocharged gasoline engines. It is particularly important to improve fuel economy under high load conditions, especially in the turbocharged region. The key points for improving fuel economy in this region are to suppress knocking, reduce the exhaust temperature and increase the specific heat ratio. There are several varieties of cooled EGR systems such as low-pressure loop EGR (LP-EGR), high-pressure loop EGR (HP-EGR) and other systems. The LP-EGR system was chosen for the following reasons. It is possible to supply sufficient EGR under a comparatively highly turbocharged condition at low engine speed. It is important for knocking suppression to remove nitrogen oxides (NOx) from the EGR gas
Takaki, Daisuke, Tsuchida, Hirofumi, Kobara, Tetsuya, Akagi, Mitsuhiro, Tsuyuki, Takeshi, Nagamine, Morihiro
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