Browse Topic: Exhaust manifolds
This study addresses the challenge of ensuring the durability of closed couple exhaust manifolds in the compact engine bays of modern vehicles, focusing on a longitudinally mounted 1.2L 4-cylinder engine. The original sheet metal Exhaust manifold design failed the thermal fatigue bench durability test, requiring a complete redesign to improve strength without changing materials. Initial simulation predictions significantly deviated from physical test results, with repeated cracks observed during accelerated thermal fatigue bench testing, despite simulations predicting a higher number of cycles before failure. This difference highlighted the need for a deeper understanding of the manifold's failure modes, primarily thermal fatigue, and mechanical vibration during engine transients. The design of experiment (DOE) approach was used to find the effect of different parameters e.g., gas temperature, surface temperature, air flow, thermal gradient, on the durability result & also to understand these parameters in real life vehicle driving conditions. This revealed the root causes of the cracks and established a dependable match between simulation and actual testing. The redesigned manifold included many key changes: increased wall thickness to enhance structural strength, a reshaped geometry to optimize flow and reduce stress points, and the addition of webbing in the port area to improve heat distribution and provide extra support. Furthermore, testing protocols were refined to replicate real-world driving conditions, including more precise temperature cycling. These refined protocols enabled the identification of design flaws and facilitated the validation of improvements. The final design successfully passed tough accelerated thermal fatigue bench testing, showing significantly improved durability. This research highlights the importance of accurate simulation modelling, targeted design improvements, and refined testing to replicate real world driving conditions in overcoming thermal challenges within tight engine spaces, leading to strong and durable exhaust systems.
Internal Combustion Engine (ICE) is the heart of an Automobile. The failure of any critical component of the ICE engine will directly affect the performance of the vehicle. The gaskets are among the many vital parts of an IC engine that are essential in ensuring appropriate sealing to prevent gas and liquid leakage and maintain optimal engine efficiency. Engines use a variety of gasket types to accommodate various sealing requirements. Among them the exhaust manifold gaskets are one of the critical gasket elements in ICE engines. Exhaust Gasket acts as a seal between cylinder head and extremely hot exhaust manifold, which prevents the leakage of hot exhaust gases produced during typical engine operating condition. The gaskets are crucial components because they endure extremely high mechanical loads from the exhaust manifold sliding and banana-shaped bending brought on by thermal expansion, as well as extremely high thermal loads from the high exhaust gas temperatures, which are more than 800°C. These gaskets are additionally subjected to extremely high bolt loads. As the gaskets are made of steel materials, due to the above Thermo-Mechanical loads, there are very high chances for wear out of the gaskets, which affects the performance characteristics & thus efficiency of the engine. Study of wear phenomenon is very challenging particularly for the gaskets because of nonlinear behavior of geometries, material nonlinearities and in addition, the gaskets are made up of numerous layers with negligible thickness, which makes it further challenging. The wear in Automobile Engine components and particularly in gaskets is an area, which has not been studied extensively. This paper majorly focuses on a computational approach to capturing the wear phenomenon on the gaskets. One of the most critical hot end durability tests of the engine was replicated in a simulation environment by considering all the relevant physics from the physical test. To simulate wear phenomenon, the classical Archard’s wear model was implemented in a UMESHMMOTION Fortran subroutine code and solved in the Finite Element Software ABAQUS/Standard. To consider the removal of material and geometry change due to wear, the Arbitrary Lagrangian-Eulerian meshing technique of ABAQUS was used.
In the power industry, high-power Diesel Generator (DG) sets often utilize high power V-engine cylinder configurations to enhance power output within a compact design, ensuring smoother operation and reduced vibration. In this V-engine configurations, the exhaust gas mass flow rate is significantly higher compared to inline engines of similar displacement, due to the greater number of cylinders operating in a compact space, which leads to a higher volume of exhaust gases expelled in a shorter duration. This necessitates the use of a dual Exhaust After Treatment System (EATS) to effectively manage NOx emissions. High-power gensets typically emit NOx levels around 9 g/kWh, presenting significant challenges for developers in adhering to stringent emission standards. To address these challenges and meet CPCB IV+ emission norms, we propose a dual urea dosing system integrated with a novel control strategy aimed at optimizing the treatment of exhaust gases. This paper introduces a dual exhaust system equipped with dual urea dosing units. By employing two controller units, we ensure compliance with On-Board Diagnostics (OBD) requirements while effectively implementing advanced software concepts. Our approach not only enhances the efficiency of NOx reduction but also provides a robust solution for high-power diesel generators, paving the way for more sustainable operations in the power sector. Furthermore, we explore the integration of real-time monitoring and adaptive control mechanisms to respond dynamically to varying load conditions and exhaust characteristics. This ensures optimal dosing of urea, enhancing the overall performance of the EATS. This study discusses the design, implementation, and performance evaluation of the proposed system, highlighting its potential to significantly lower NOx emissions while maintaining operational efficiency in high-power diesel generator applications.
Modal performance of a vehicle body often influences tactile vibrations felt by passengers as well as their acoustic comfort inside the cabin at low frequencies. This paper focuses on a premium hatchback’s development program where a design-intent initial batch of proto-cars were found to meet their targeted NVH performance. However, tactile vibrations in pre-production pilot batch vehicles were found to be of higher intensity. As a resolution, a method of cascading full vehicle level performance to its Body-In-White (BIW) component level was used to understand dynamic behavior of the vehicle and subsequently, to improve structural weakness of the body to achieve the targeted NVH performance. The cascaded modal performance indicated that global bending stiffness of the pre-production bodies was on the lower side w.r.t. that of the design intent body. To identify the root cause, design sensitivity of number and footprint of weld spots, roof bows’ and headers’ attachment stiffness to BIW, panel gages, body pillars joints’ attachment stiffness etc. was conducted using CAE tools. Identified structural weaknesses were converted into optimum design solutions, which were then validated using Experimental Modal Analysis (EMA). The proposed structural modifications in the body showed good improvement in the idle tactile vibrations and overall NVH of all production vehicles, validating the whole approach.
The exhaust manifold of a high-performance motorcycle engine is subjected to combined thermal and vibrational loadings. In this research, the whole fatigue assessment of an exhaust manifold is addressed. First, a classic low-cycle fatigue analysis is performed. Then, a specific methodology for determining the fatigue cycle of components subjected to thermal and vibration loadings is developed and presented in a way that possible damages can be evaluated. The results are post-processed and the damage caused by fatigue cycles is computed referring to the Wöhler curve of the material using the Dirlik approach.
Although the brake thermal efficiency of the state-of-the-art Atkinson-cycle hybrid engines have reached 41%, such engines typically have a low specific power. The ideal hybrid engines for SUVs should have a high thermal efficiency as well as a high specific power. Jiangling Motors recently developed a 4-cylinder, 1.5L TGDI hybrid Miller engine for powering mid-size SUVs, which has achieved 42% brake thermal efficiency, 19.3-bar BMEP, and 73.3-kW/L specific power. The engine has a high compression ratio, a long stroke, and is equipped with a low-pressure EGR system. It can operate with the stoichiometric mixture on the full engine map, with the help of the water-cooled exhaust manifold and the intelligent thermal management system.
Future Diesel engines must meet extended requirements regarding air-fuel ratio, exhaust gas recirculation (EGR) capability, and tailored exhaust gas temperatures in the complete engine map to comply with the future pollutant emission standards. In this respect, parallel turbines combined with two separate exhaust manifolds have the potential to increase the exhaust gas temperature upstream of the exhaust aftertreatment system and reduce the catalyst light-off time. Furthermore, variable exhaust valve (EV) lifts enable new control strategies of the boosting system without additional actuators. Therefore, hardware robustness can be improved. This article focuses on the parallel-sequential boosting concept (PSBC) for a high-performance four-cylinder Diesel engine with separated exhaust manifolds combined with EV deactivation. One EV per cylinder is connected to one of the separated exhaust manifolds and, thus, connected to one of the turbines. By closing one of the EVs, the corresponding exhaust manifold and the connected turbine are deactivated. The engine operates in mono-turbo mode at low power output. The second turbocharger (TC) blends in as the power requirement increases. A novel design process for complex turbocharging systems is presented, which bases on a validated one-dimensional (1D) gas-exchange simulation model with an advanced TC modelling methodology. The design process handles the high degree of freedom in the layout process with clearly defined optimization steps based on identified system limitations. The modelling of the heat transfer within the TCs has been calibrated with measurement data from a hot gas test bench. This enables an accurate prediction of the exhaust gas temperature upstream of the exhaust aftertreatment system. The designed parallel sequential boosting system demonstrates high potentials in full-load and part-load operation, increasing the exhaust gas temperature downstream of the turbine by up to 40°C at an engine speed of n = 1250 1/min and a brake mean effective pressure of BMEP = 2.7 bar compared to the baseline engine with a serial-sequential boosting concept (SSBC). Furthermore, a higher rate of high-pressure EGR can be generally achieved with that system.
This paper discusses design and optimization process for the integration of exhaust manifold with turbocharger for a 3 cylinder diesel engine, simulation activities (CAE and CFD), and validation of manifold while upgrading to meet current BS6 emissions. Exhaust after-treatment system needs to be upgraded from a simple DOC (Diesel Oxidation Catalyst) to a complex DOC+sDPF (Selective catalytic reduction coated on Diesel Particulate Filter) to meet the BS6 emission norms for this engine. To avoid thermal losses and achieve a faster light-off temperature in the catalyst, the exhaust after-treatment (EATS) system needs to be placed close to the engine - exactly at the outlet of the turbocharger. This has given to challenges in packaging the EATS. The turbocharger in case of BS4 is placed near the 2nd cylinder of the engine, but this position will not allow placing the BS6 EATS. Hence, the turbocharger position must be shifted to such an extent that it is placed before the first cylinder resulting in an overhanging design. This needed sufficient design optimization through CAE and CFD simulations. CFD simulations are performed to predict the surface temperatures of the manifold using conjugate heat transfer (CHT) analysis. HCF and LCF simulations were performed to optimize the wall thickness and merging radii given along with the stiffening ribs in the exhaust manifold. The overhang design of turbocharger posed a challenge in sealing the exhaust manifold and cylinder head joinery, this has been optimized using CAE simulations. The paper also discusses the correlation between simulation and validation results. The finalized design has been validated on both engine testbed and vehicle successfully.
Typical diesel engine-out emissions consist of hydrocarbons (HC), carbon monoxide (CO), particulate matter (PM) & oxides of nitrogen (NOx). The HC and CO emissions are oxidized by a diesel oxidation catalyst (DOC), placed upstream, closer to the exhaust manifold. The DOC is often followed by a diesel particulate filter (DPF), which entraps and combusts PM. The NOx is often controlled by a selective catalytic reduction (SCR) catalyst. An SCR catalyst commonly uses NH3 to reduce the NOx to N2. Vanadium-based SCR catalysts have been widely used for many years. More recently, Cu-Zeolite based SCR (CuZ-SCR) is gaining much attention primarily due to the potential environmental hazards of vanadium and a wider temperature window of effective operation. The SCR reaction is facilitated by the presence of NO2 at lower exhaust gas temperatures by means of the so-called “fast” reaction. However, this is only advantageous up to about 300°C. At higher temperatures, the contribution of NO2 is insignificant, since mass transfer & diffusion phenomenon become dominant in NOx conversion enabling the “standard” SCR reaction to proceed. In this study, the CuZ-SCR catalyst performance was tested as fresh and as high temperature aged (>800°C) on an engine test bed using a 0.7 L diesel engine and Non-Road Steady-state Cycle (NRSC). The NOx conversion efficiency of the CuZ-SCR catalyst during alpha (NH3/NOx) changes, NO2/NOx ratio changes and space velocity changes was established. Entire Full Useful Life (FUL) NOx emission control performance was evaluated for a novel CuZ-SCR catalyst placed downstream of a DOC & DPF in a DOC+DPF+SCR catalyst system. In order to evaluate FUL durability, including high temperature durability (exotherm functions) with multiple active DPF regeneration events (≥600°C) and sulfation/desulfation events, the catalyst system was exposed to a customized cycle for continuous 450 aging cycles, equivalent to the FUL thermal load and sulfur exposure of a vehicle over 160000 km. The performance of the novel CuZ-SCR catalyst was tested using the NRSC 8-mode test cycle after every continuous 50 cycles in 450 aging cycles. The results show that the novel Cu-ZSCR catalyst has excellent NOx reduction performance over a wide temperature range from low to high, as well as excellent durability to FUL.
SAIC Motor has developed an all new 2.0 L 4-cylinder turbocharged gasoline direct injection engine to meet the market demand and increasingly stringent requirement of CAFE and tail-pipe emission regulations. A series of advanced technologies have been employed in this engine to achieve high efficiency, high torque and power output, fast response low-end torque performance, refined NVH performance, all at market leading level, and low engine-out emissions. These main technologies include: side mount gasoline direct injection with 35MPa fuel injection system, integrated exhaust manifold, high tumble combustion system, 2-step intake variable valve lift (DVVL) with Miller Cycle, efficient turbo charging with electric wastegate (EWG), light weight and compact structural designs, NVH measures including balancer system with silence gear, friction reduction measures, optimized thermal management, etc. As a result of application of these technologies and optimized designs, the engine is able to achieve over 39.5% maximum brake thermal efficiency (BTE), as well as large high efficiency region in the fuel map that covers most typical customer real driving conditions. It delivers 360 Nm maximum torque from 1500RPM to 4000RPM, and 172kW rated power at 5500RPM, with fast low end torque response. The new 2.0T engine already started the mass production in October, 2020, with its first application in ROEWE iMAX8, a MPV. Even with the weight of 2058kg, the vehicle is able to achieve 9.3s 0-100km acceleration, while meeting China VI b standard emission regulatory requirement equipped with this new 2.0T engine. In this paper, the design/optimization of the engine systems will be described. The detailed investigations with simulations and dyno testing of effects of the core technologies will also be presented.
The introduction of real driving emissions cycles and increasingly restrictive emissions regulations force the automotive industry to develop new and more efficient solutions for emission reductions. In particular, the cold start and catalyst heating conditions are crucial for modern cars because is when most of the emissions are produced. One interesting strategy to reduce the time required for catalyst heating is post-oxidation. It consists in operating the engine with a rich in-cylinder mixture and completing the oxidation of fuel inside the exhaust manifold. The result is an increase in temperature and enthalpy of the gases in the exhaust, therefore heating the three-way-catalyst. The following investigation focuses on the implementation of post-oxidation by means of scavenging in a four-cylinder, turbocharged, direct injection spark ignition engine. The investigation is based on detailed measurements that are carried out at the test-bench. Due to the complexity of the investigated phenomenon, the analysis at the test-bench has been sustained by 3D-CFD simulations. At first a 3D-CFD full-engine model has been implemented to reproduce the complete engine from the air-box up to the turbine inlet. This model is able to simulate all the relevant full-engine effects like scavenging, cylinder-to-cylinder interaction and local inhomogeneity inside the cylinder. The second implemented model focuses on the exhaust manifold, from the exhaust valve up to the turbine volute, and it is characterized by a fine computational grid and by the implementation of a chemical reaction mechanism. Both models have been validated using the detailed measurements of the test-bench. The simulation matched precisely the measurements and enabled a better interpretation of experimental data. The simulation methodology has been applied also to other engine operating points enabling a mapping of post-oxidation, the development of a post-oxidation model for 1D engine simulation and the implementation of a simplified model for the full-engine simulation.
The introduction of real driving emission measurements increases the need of improved transient engine behavior while keeping the emissions to a minimum. A possible way of enhancing the transient engine behavior is the targeted usage of scavenging. Scavenging is realized by an inlet- and exhaust-valve overlap. Fresh scavenging air flows directly from intake manifold through the cylinder into the exhaust manifold. Therefore, the mass flow at the turbine increases and causes a reduced turbo lag, which results in a more dynamic engine behavior. The unburned oxygen causes a decrease of the three-way catalyst (TWC) conversion rate. To keep the TWC operation close to stoichiometry, a rich combustion is performed. The rich combustion products (most notably carbon monoxide) mix in the exhaust manifold and react with oxygen so that the conversion rate of the TWC is ensured. In order to investigate the potential and risks of this engine operating strategy, a reliable 1D engine model is necessary. This work deals with the description of the most important aspects of the post-oxidation phenomenon and with the development of a 1D post-oxidation model, based on detailed 3D-CFD simulation results including a reaction mechanism. The 3D-CFD simulation permits a deep insight on the mixing effects inside the exhaust manifold (interaction of all four cylinders) and the resulting chemical reactions. The 1D post-oxidation model is capable of making a statement on the amount of scavenging air, which can be burned inside the exhaust manifold before reaching the TWC. The modelling approach relies on the mixing effect inside the manifold and on a chemical conversion of the emissions.
Low pressure exhaust gases recirculation (LP-EGR) is becoming a state-of-the-art technique for Nitrogen oxides (NOx) reduction in compression ignited (CI) engines. However, despite the pollutant reduction benefits, LP-EGR suffers from strong non-linearities and delays which are difficult to handle, resulting in reduced engine performance under certain conditions. Measurement and observation of oxygen concentration at the intake have been a research topic over the past few years, and it may be critical for transition phases (from low pressure to high pressure EGR). Here, an adequate selection of models and sensors is essential to obtain a precise and fast measurement for control purposes. The present paper analyses different sensor configurations, with oxygen concentration measurements at the intake and exhaust manifold and combines observation techniques with sensor models to determine the potential of each configuration. Experimental results from a 2.2 l. diesel engine are used to validate the presented techniques.
A real-time control-oriented mean value engine plant model that includes engine thermals and cold starts is developed for a Toyota Prius 2015 plug-in hybrid engine in Modelica and MapleSim and validated experimentally. The model consists of an engine block model, intake and exhaust manifold models, and a throttle model. An advantage of the engine block model is the ability to compute the frictional Mean Effective Pressure during engine cold starts from calculated air, oil, and coolant temperatures at various locations in the engine block. Traditionally, engine thermals are modelled utilizing thermal resistances and capacitors. The proposed model utilizes linear graph theory with terminal equations to study the topology of the different components that affect engine thermals, including engine head, liner, coolant, and oil sump. Linear graph theory is introduced as a methodological tool able to represent the various components included in the thermal engine model, reducing the complexity of automated differential-algebraic equations generation. The generated model equations are solved using a generic solver. The throttle model is extended to include reverse air flows, extending the optimization range in model predictive controllers. Bench tests are conducted on a Toyota Prius engine where the flow rates, temperatures, and pressures are measured over the engine air path. The respective temperatures and pressures are measured over the different engine components along with the engine torque and speed for different engine settings. Experimental values are utilized to estimate various parameters for the new engine models. The developed model is integrated with an engine manifold model that includes 1-D spatial variation developed by integrating Orthogonal Collocation with the Method of Characteristics. The manifold model solves the one-dimensional Euler equations used to model compressible quasi-one-dimensional flow with heat transfer and friction effects. Discharge rates and engine friction mean effective pressures are compared with experimental data. In summary, a validated real-time engine model that captures important dynamic phenomena and suitable for control applications is developed, allowing simulations with other engine air path models created using Modelica.
In recent years, the automotive industry has been increasingly committed to developing new solutions for better and more efficient engines. One of them is the use of new insulating materials (thermal conductivity < 0.4 W/m-K, heat capacitance < 500 kJ/m3-K) to coat the engine combustion chamber walls, as well as the exhaust manifold. The main idea when coating the combustion chamber with these materials is to obtain a reduction of the temperature difference (thermal swing) between gas and walls during the engine cycle and minimize heat losses. Experimental measurements of the possible performance improvements are very difficult to obtain, mainly because the techniques available to measure wall temperature are limited. Therefore, simulations are typically used to investigate insulated combustion chambers. Nevertheless, the new generation of insulating coatings is posing challenges to numerical modelling, as layer thickness is very small (~100 μm). Indeed, a detailed modelling would require additional cells refinement for the coating layer and therefore significant increase in computational effort and simulation time. In this regard, a novel strategy to model thin coating layers in the combustion chamber walls is presented in this paper. The approach consists in the definition of a thicker equivalent coating material that reproduces the thermal behavior of the real thin coating. The calculations are performed using a commercial 3D-CFD software for a Diesel engine considering two configurations: conventional metallic piston and coated piston top. Finally, the results are compared to assess the impact of the new generation of insulating coatings on engine performance.
With high peak pressure demands and the need for improved engine efficiency, it has become necessary to use lighter and stronger materials for different engine components. Compacted Graphite Iron (CGI) in this area is a promising candidate and is currently used for many casting parts like cylinder block, head, cylinder liner, exhaust manifold, engine frame, etc. The internal quality of these components made from CG iron is crucial for improved engine performance. The internal quality, in turn, depends upon the soundness and solidification behavior of casting components. However, there exist very limited data on the solidification behavior of CG iron for different engine castings. Due to the narrow range of microstructure stability, CG iron production and its solidification is a quite challenging process. In this paper, a study is undertaken for one such engine component exhaust manifold made from CG iron. An in-depth analysis is carried out on exhaust manifold casting to understand its solidification behavior using a casting simulation software MAGMA. Using the simulation, phenomena associated with fluid flow, temperature distribution, mushy zone formation, hot spot, and shrinkage were examined. Microstructure predictions like nodularity were also studied. Prediction of residual stresses and strains in the casting upon solidification were understood for CG iron through simulation. Finally, a comparison was made with all the above solidification parameters of CG iron with another widely used Si-Mo ductile iron material for the exhaust manifold. CG iron showed improved fluidity, higher heat loss, lesser area of hot spot, and lesser porosity formation tendencies compared to Si-Mo ductile iron. It showed a higher amount of residual stresses than Si-Mo due to differences in thermal conductivity and thermal expansion coefficients. Tendencies for warpage and dimensional stability were also compared and found to be better with CG iron than Si-Mo ductile iron
A careful study of the effect of shape variation on inflow characteristics and the role of mullite coating on the thermal stability of exhaust manifold is the main aim of the present research article. The circular and semi-circular cross-section of the exhaust manifold are utilized in the present inquiry. An internal coating thickness of 1 mm has been used on the exhaust manifold. The prediction of natural frequencies and the variation of stress and deformation with frequency have been presented through modal analysis and simple harmonic analysis. The entire work has been carried out in the computational domain with the usage of ANSYS 19.2 general-purpose software to obtain the augmented results. The creation of mullite coating has resulted in the comprehensive decrement of heat flux of around 41.06% in the circular manifold and 34.84% in the semi-circular manifold. The noteworthy deformation reduction is also noticed with the application of mullite coating. Substantial thermal stability of semi-circular exhaust manifold is the final outcome of the present research study.
Mechanical friction and heat transfer in internal combustion engines are two highly researched topics, due to their importance on the mechanical and thermal efficiencies of the engine. Despite the research efforts that were done throughout the years on both these subjects, engine modeling is still somewhat limited by the use of sub-models which do not fully represent the phenomena happening in the engine. Developing new models require experimental data which is accurate, repeatable and which covers wide range of operation. In SAE 2018-01-0121, the conventional pressurized motored method was investigated and compared with other friction determination methods. The pressurized motored method proved to offer a good intermediate between the conventional motored tests, which offer good repeatability, and the fired tests which provide the real operating conditions, but lacks repeatability and accuracy. A ‘shunt pipe’ was utilized between the intake and exhaust manifolds which reduced significantly the air supply demand. In SAE 2019-01-0930, Argon was used in place of air in the experimental setup which resulted in bulk gas temperatures synonymous to the fired engine. In SAE 2019-24-0141 and SAE 2020-01-1063 mixtures between air and Argon were utilized to investigate the relationship of mechanical friction with a controlled gradual increase in the bulk in-cylinder temperature. In this publication, a one-dimensional engine model is developed to assess the capability of the 1D model to capture the effects on the motored engine imposed by changing the working gas. From the experimental studies on the pressurized motored engine, increasing the proportion of Argon to air showed an increase in the peak bulk gas temperature of around 600°C. This resulted in an increase in the heat losses, a decrease in the pumping losses and no measureable difference in the mechanical friction.
In this research, simulation and experimental investigation of H2 emission formation and its influence during the post-oxidation phenomenon were conducted on a turbo-charged spark ignition engine. During the post-oxidation phenomenon phase, rich air-fuel ratio (A/F) is used inside the cylinder. This rich excursion gives rise to the production of H2 emission by various reactions inside the cylinder. It is expected that the generation of this H2 emission can play a key role in the actuation of the post-oxidation and its reaction rate if enough temperature and mixing strength are attained. It is predicted that when rich combustion inside the cylinder will take place, more carbon monoxide (CO)/ Total Hydro Carbon (THC)/ Hydrogen (H2) contents will arrive in the exhaust manifold. This H2 content facilitates in the production of OH radical which contributes to the post-oxidation reaction and in-turn can aid towards increasing the enthalpy. Through simulations, it was also investigated that higher H2 levels influences the ignition delay of the post-oxidation reaction significantly. In addition, the experimental investigation of H2 formation with different overlap and spatial distribution were also analyzed. It was noted that the H2 formation always came to be higher at high overlap (90 deg. overlap) due to significant scavenging in the exhaust manifold that leads in-cylinder mixture rich. Also, the H2 concentration firstly increases when we move from exhaust port to Turbocharger (TC) upstream. This is due to the inhomogeneity that occurred between exhaust port to TC upstream. Furthermore, as we move from TC upstream to TC downstream, the H2 level decreases due to the consumptions of H2 in post-oxidation reaction.
The present study examines the impact of using low thermal mass (LTM) turbine housing designs on the transient characteristics of the turbine outlet temperature for a light-duty diesel standard certification cycle (FTP75). For a controlled exhaust flow, the turbine outlet temperature will directly determine the impact on an aftertreatment system warm-up from a cold state, typical of engine-off and engine idling conditions. The performance of the aftertreatment system such as a Selective Catalytic Reduction (SCR) system is highly dependent on how quickly it warms up to its desirable temperature to be able to convert the harmful oxides of Nitrogen (NOx) to gaseous Nitrogen. Previous works have focused on mostly insulating the exhaust manifold and turbine housing to conserve the heat going into the aftertreatment system. The use of LTM turbine housing has not been previously considered as a means for addressing this requirement. The current study explores this in detail and shows that the use of LTM turbine housing improves the rise in turbine outlet temperatures quickly. Three turbine housing designs developed by Cummins Turbo Technologies (CTT) were studied with baseline, 20% reduced, and 40% reduced thermal masses. The analysis is performed using a GT-Power engine model, which uses the transient inputs for the simulation from the engine test conducted using the prototype baseline turbine housing. The 40% reduced thermal mass turbine housing is shown to improve the rise in turbine outlet temperature by as much as 21 K in the first 400 s of the Federal Test Procedure (FTP) cycle. This is expected to significantly improve the performance of the aftertreatment system and is verified by an aftertreatment simulation conducted with engine-out results from the present analysis as boundary conditions to the aftertreatment model. The 40% reduced thermal mass case showed a marked reduction in NOx by as much as 15% from the baseline turbine housing case during the first 400 s of the FTP cycle. A detailed look at the turbine housing metal temperatures and the turbocharger heat transfer distributions are provided to explain the fundamental reasons for the improved exhaust temperature for the lower thermal mass housing material.
In recent years, worldwide automotive manufacturers have been continuously working in the research of suitable technical solutions to meet upcoming stringent Real Driving Emission (RDE) and Corporate Average Fuel Economy (CAFÉ) targets, as set by international regulatory authorities. Many technologies have been already developed, or are currently under study by automotive manufacturer for gasoline engines, to meet legislated targets. In-line with the above objective, there are many technologies available in the market to expand lambda 1 (λ=1) region by reducing fuel enrichment at high load-high revolutions per minute (RPM) by reducing exhaust gas temperature (for catalyst protection) for RDE regulation [1]. Integrated Exhaust Manifold (IEM) is the key technology for the Internal Combustion (IC) for the subjected matter as catalyst durability protection is done by reducing exhaust gas temperatures instead of injecting excess fuel for cooling catalyst. Additionally, this technology also helps in cost saving due to reduced parts count, in engine weight reduction, improve the response and increase fuel economy during the cold start stage of Modified Indian Driving Cycle (MIDC) and Worldwide harmonized Light vehicles Test Cycles (WLTC) by faster warm-up of coolant in cold stage and also fuel enrichment reduction (reduced fueling requirement) in high-speed regions of these cycles as shown in Figure 1.
In this research, a novel methodology for the post-oxidation in a turbocharged spark ignition (SI) engine is proposed and investigated that can improve the emissions along with the reduction in turbo-lag. In this research, both simulation and experimental activities are performed. The 1-D simulation model was used for the identification of efficient scavenging. Thereafter, experimental validation tests for modeling and post oxidation were conducted on a 4-cylinder turbocharged SI engine. From the results, it was revealed that efficient scavenging and post-oxidation can be obtained at lower speed and higher load. The enthalpy in exhaust manifold increased due to the post-oxidation reaction which in turn increased the temperature and pressure of the exhaust gases and hence emissions reduced. Also, due to the increased enthalpy at turbine upstream, the turbocharger speed increased and as a consequence, reduction in the turbo-lag was observed. It was also noted that the post-oxidation is limited at higher load and overlap in an inline 4-cylinder engine due to the strong scavenging which increased the cooling effect in in-cylinder and exhaust manifold due to excess air.
Energy policy reviews state that automobiles contribute 25% of the total Carbon dioxide (CO2) emission. The current trend in emission control techniques of automobile exhaust is to reduce CO2 emission. We know that CO2 is a greenhouse gas and it leads to global warming. Conversion of CO2 into carbon and oxygen is an energy-consuming process compared to the catalytic converters. The best way to reduce CO2 is to capture it from the source, store it and use it for industrial applications. To physically capture the CO2 from the engine exhaust, adsorbents like molecular sieves are utilized. In comparison to other CO2 separation methods, adsorption technique consumes less work and energy. Moreover, the sieves can be regenerated, reused and recycled once it is completely saturated. In this research work, zeolite X13 was chosen as a molecular sieve to adsorb CO2 from the exhaust. A chamber was designed to store the zeolite and it is attached to the exhaust manifold. The selected engine was a single-cylinder Briggs and Stratton petrol engine. The experiments were conducted in two phases, the first phase to adsorb and the second phase to regenerate. Temperature pressure swing adsorption was chosen as the preferred process for the regeneration. This study was conducted by varying chamber length in three measurements and sieve quantities. The gas separated from the sieves during regeneration is tested using AVL Ditest analyser to study the percentage of CO2 adsorbed from the engine exhaust. From the results, it was found that 70% of the CO2 emissions were absorbed using low cost zeolite sieves.
Items per page:
50
1 – 50 of 570