Engine Exhaust Manifold Research Articles

Exploring ultrafine particle emission characteristics from in-use light-duty diesel trucks in China using a portable measurement system

Diesel vehicle exhaust is one of the major contributors to ultrafine particles (UFPs) in urban areas in China. However, there is still a lack of knowledge about UFPs emission characteristics from current in-use diesel vehicles. This study has carried out an on-road test of 10 in-use Light-duty Diesel Trucks (LDDTs) with different emission control standards in China using a self-established portable measurement system based on the Electronic Low-pressure Impactor (ELPI) and characterized the ultrafine particle number (PN) concentration, particle size distribution and metal element contents. The results revealed a significant reduction of 93.37% in the average PN0.1 emission factor of LDDTs from China IV to China VI. Notably, LDDTs compliant with the China VI vehicle emission control standard exhibited the lowest PN0.1 and PM0.1 emission factors, measuring 4.991×1014 #/km and 0.627 g/km, respectively. By taking into account emissions under real driving conditions, we found that the PN emission rates grow with the increase of the Vehicle Specific Power (VSP). The cold-start phase had higher PN emissions than the hot-start phase, with 8590, 1890, 477, and 22 times higher than those of the ambient air (1.18×105 #/cm3), respectively. The installation of Diesel Particulate Filter (DPF) can decrease UFPs by more than 99.8%, while the PN emission factor during the DPF regeneration stage (1.85×1016 #/km) increased by 5 orders of magnitude that of the DPF normal works (7.51×1011 #/km). Metal element contents analysis shows that Fe, Ca, Al and Mg are the dominant elements in UFPs of LDDT exhaust gas, but the element of Ni is slightly increasing in a China VI, possibly due to the new automotive engine exhaust manifolds being made of Ni instead of cast iron for the purpose of having more high-temperature resistance. Our study demonstrates the importance of monitoring and routine maintenance of exhaust after-treatment systems.

Determining infrared radiation intensity characteristics for the exhaust manifold of gas turbine engine ТВ3-117 in МІ-8МSB-B helicopter

The object of this study is the screen-exhaust device in the TV3-117 engine of the Mi-8MSB-B helicopter. To reduce visibility in the thermal range, a system of mixing hot engine exhaust gases with ambient air is used; this technique makes it possible to reduce the infrared radiation of engines. For this purpose, a new sample of screen-exhaust device was designed for testing. A thermal imaging survey of the helicopter was conducted. Three variants of thermal images were acquired: a helicopter without installation of a thermal visibility reduction system, a helicopter with standard exhaust shields installed, and a helicopter with newly developed shield exhaust devices installed. Based on the obtained experimental results, the characteristics of the intensity of infrared radiation were determined for three variants of research in the range of thermal waves of 3–5 μm. The study uses a comprehensive approach to solving the tasks, which includes a statistical analysis of known and promising ways to protect a helicopter from guided missiles with infrared homing heads based on reduced radiation forces and a theoretical method for calculating flow and temperature fields. The advantages of placing the section of the exhaust channel of the designed screen-exhaust device in the horizontal plane for complete shielding of infrared radiation in the lower hemisphere have been experimentally proven. The benefits of directing the flow of exhaust gases from the screen-exhaust device into the space above the helicopter propeller and dividing this flow into four separate flows were shown. The results of experimental research could be used to design new or improve existing screen-exhaust devices by the developers of military aviation

Topological optimization of structures with thermomechanical loading under compliance constraints for 3D printing applications

Currently, due to the high costs of production and expensive raw materials, approaches, including, making models smaller and lighter, are especially considered in the design of structures. In order to better describe the capabilities, efficiency, and limitations of an innovative field called topology optimization, various practical problems under different loadings and boundary conditions were evaluated in this study. Optimization algorithms were used in ANSYS software for the optimization of a cantilever beam under static loading, double-girder beam and a dome-shaped geometry under static and thermal loading, a hot fluid transfer tee and an engine exhaust manifold under static loading and convection heat transfer. The results showed that the reduced volume in the final models were equal to 66.29%, 52.88%, 50.05%, 51.85%, and 35.02%, respectively. Consequently, this reduced volume causes some increase in the tension, and displacement of the final model, which can adjust them according to the limitations governing the problem. Furthermore, the amount of increase in the average value of the stress in the cantilever beam, double-girder beam, and dome-shaped geometry were 88, 800, and 6 MPa, and the average amount of displacement in these samples increased by 10.2%, 200%, and 3.3%, respectively. Challenges, and manufacturability of optimized problems were investigated by 3D printing of a dome-shaped model using the FDM method, which illustrated that the output product has a suitable level of accuracy and smoothness. Subsequently, by using supporting structures, three-dimensional holes were created with proper precision in the 3D-printed sample, which satisfied the manufacturability of relatively complex models.

Effect of ceria–silica-based synthesized catalyst in a CI engine exhaust system operating with plastic oil blend

This study investigates the impact of ceria–silica (Ce–Si)-based catalyst integrated in the catalytic converter (CC) on the compression ignition (CI) engine's exhaust manifold. The synthesis catalyst, Ce–Si was developed with the solvothermal method and aged for 4 h at 55°C. Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, thermogravimetric analysis, energy dispersive X-ray spectroscopy and transmission electron microscopy analyses were carried out to conclude the synthesis of the catalyst. The catalyst performance of the CC was tested for the emission behavior of nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbon (HC) and smoke. A custom-built CC was installed on the test engine's exhaust manifold. The synthesis catalyst was installed in the engine exhaust route of the stationary single-cylinder diesel engine to conduct the study. To determine the effect of the synthesis catalyst on the exhaust manifold to test both diesel and DPB (B50) fuel with and without CC. Under maximum load conditions, the presence of CC reduced oxide of nitrogen and carbon monoxide emissions by 23% and 17%, respectively, compared to diesel. The synthesized aerogel catalyst has a low density and a high surface area relative to its volume. Ce–Si aerogel catalyst can be used to improve the conversion efficiency of nitric oxide (NO), unburned hydrocarbon and CO in the three-way CC.

Using the thermodynamic processes features to assess the diesel power plants technical condition

The results of studying the thermodynamic processes features and analyzing the prospects for using their characteristics to assess the technical condition of diesel power plants are contained in the paper. A structural diagram of a ship power plant, which is proposed to be considered consisting of separate components of mechanical part, thermodynamic part, fuel supply system and automatic speed control system equal in degree of influence on efficiency is proposed. The theoretical analysis results of the joint operation of the mechanical and thermodynamic components of the diesel power function have shown that the temperature of the working surfaces is an important characteristic of the power plant technical state. The concept of the thermodynamic component in this case refers to a combination of fuel combustion processes and combustion product expansion. To improve the design and efficiency of power plants operation, it is necessary to further study the in-cylinder fuel combustion processes and develop operational methods for monitoring the thermal state of diesel internal combustion engines. Control of changes in functional dependencies of working medium temperature on operating conditions and technical condition can in practice contribute to increase the efficiency of ship power plants operation. The experimental studies of the thermal imaging methods prospects to assess the diesel engines technical condition are carried out. It is found that the control reliability increases with an increase in the size of the diesel engine frame due to a decrease in the intensity of the dynamics of temperature equalization of individual cylinders. At the same time, the most expedient and informative is the control of the temperature of the diesel engine exhaust manifold, carried out during the heating of the cold engine or immediately after its completion.

Design and Analysis of the Exhaust Manifold in a 6-Cylinder Commercial Diesel Engine

The exhaust manifold is one of the engine parts in internal combustion engines that operates under the influence of high temperatures. To prevent issues arising from the expansion movement due to high temperature effects, the exhaust manifold of a 6-cylinder commercial diesel engine has been designed in three parts. Sealing rings that can withstand high temperatures are used in the three-part exhaust manifold to prevent gas leaks. For the exhaust manifold, 1-dimensional, thermal, flow, and structural analyses have been performed. Initially, based on the structural analysis of the exhaust manifold conducted without sealing rings, sealing ring selection was made according to the deformation values of the exhaust manifold. In the structural analysis, the PEEQ (equivalent plastic strain) method, which is utilized to determine the thermomechanical fatigue crack initiation area, is employed. In this study, an approach using this method was undertaken, and the crack initiation area was examined.

Failure analysis of a natural gas engine exhaust manifold

The causes of exhaust manifold failure of a natural gas engine were investigated in terms of both the material and structure. First, the material analysis, including chemical component and mechanical properties, were carried out by material tests and data analysis. Then, the temperature and thermal stress of exhaust manifold under thermal shocks were calculated by finite element method. Finally, the initiation and propagation of cracks and improvement design of exhaust manifold were discussed. The results showed that the highest temperature of exhaust manifold was 715 °C and the maximum thermal stress was 455 MPa. The yield deformation occurred during thermal shocks. And the sharp structural change at the critical induced thermal stress area raised the possibility of shrinkage pores. Therefore, the low cycle fatigue failure was the main reason of the exhaust manifold failure. And structure optimization and alternation of material properties were two most basic and effective technological approaches.

Unsteady gasdynamic modeling of double-entry turbine integrated with engine exhaust manifolds

Pulsating turbocharging system with a dual-entry turbine is always applied for the utilization of pulsating energy and improvement of low-speed torque for the internal combustion engine. With the enhancement of pulsating energy via the pulsating turbocharging system and dual-entry turbine, the interaction between exhaust manifolds and dual-entry turbine cannot be disregarded by either side when confronted by pulsating inflows. This paper proposes a gasdynamic model of double-entry turbine coupling with exhaust manifolds to examine the interaction effect between turbine and exhaust manifolds. This gasdynamic model can predict the propagation of pressure and mass flow rate from exhaust manifolds to the double-entry turbine as well as transient turbine performance. Predictions of this gasdynamic model are validated against detailed 3-D simulation and show good consistency with 3-D results. The performance and energy distribution of the double-entry turbine coupled to exhaust manifolds under various pulsating conditions are thoroughly discussed via this reduced-order model. Results show that with increasing frequency or amplitude of pulsating inflows imposed on inlets of the exhaust manifolds, the performance of the entire system deviates from the quasi-steady hypothesis, particularly the swallowing capacity. This phenomenon indicates that the matched operating point between the turbine and engine deviates from the quasi-steady conditions. In addition, exhaust manifolds geometries have a notable impact on turbine performance and energy distributions in exhaust systems. It is found that with an increase in the volume or length of the exhaust manifolds, the pulse at the turbine inlet is amplified, and available energy at the turbine inlet is increased, even though the inlet conditions of exhaust manifolds remain unchanged. This study may provide a guiding effect for the optimization of the turbo-engine matching process and the development of high-performance turbocharged engines.

Hydrocarbon and particulate matter evolution in the exhaust manifold of a spark-ignited engine under cold-start operation

Cold-start, as defined by the time between first engine crank and three-way catalyst light-off, is responsible for a large percentage of NOx, unburned hydrocarbon, and particulate matter (PM) emissions in light-duty engines. Minimizing emissions during cold-start is a trade-off between achieving faster three-way catalyst light-off, and engine out emissions during that period. In this study, various exhaust gas and PM species were measured at three locations in the exhaust manifold using advanced hydrocarbon and PM speciation methods in addition to standard exhaust-gas-analyzers to characterize how or if these species evolve downstream of the exhaust port during cold-start operation. A gasoline direct injected spark ignited (DISI) single cylinder engine was run at 2-bar net indicated mean effective pressure (NIMEP) at spark timings ranging from normal-SI operation relevant early spark timing of -10 degrees after top dead center firing (dATDCf) to more cold-start-relevant retarded spark timing of 25dATDCf. At the retarded spark timings, the exhaust manifold gas temperature increased downstream of the exhaust port indicating the presence of oxidation reactions that counteract heat transfer losses; a trend also supported by oxidation of total hydrocarbons (THC), CO, and H2 observed downstream of the exhaust port. Additionally, increase in NOx emissions downstream of the exhaust port indicated presence of high temperature required to drive NOx chemistry. Aromatics were the largest exhaust hydrocarbon species group detected at all spark timings, while the paraffins were under-represented from their fuel composition fraction. Organic carbon accounted for more than 95% of the PM mass at exhaust port for all spark timings. At retarded spark timings, the PM mass reduced downstream of the exhaust port primarily driven by organic carbon oxidation. Particle number and size measurements at retarded spark timings indicated a reduction in particle count downstream of the exhaust port with an accompanying increase in particle size possibly due to agglomeration.

Development of an experimental/numerical validation methodology for the design of exhaust manifolds of high performance internal combustion engines

Several typical failure modes in the exhaust manifold of an internal combustion engine are commented on. In particular, thermal loading and the related thermal fatigue damage mechanism are addressed. The component under investigation is a cast exhaust manifold including the turbine involute. Finite Element simulations are performed, and a numerical methodology is presented to interpret and understand the observed failures, with the aim of developing a useful tool to virtually validate the component, before the manufacturing phase. The Finite Element analysis closely mimics the experimental validation procedure that considers several heating and rapid cooling cycles to simulate typical engine operating conditions. A static mechanical characterization at high temperatures of the materials involved is carried out, aimed at identifying a suitable alloy and its mechanical characteristics useful for feeding the numerical models. The developed design methodology proposes a damage criterion for thermal fatigue investigation, considering the elastoplastic behaviour of the material when subjected to high temperature cycles. In particular, the accumulated equivalent plastic strain range for a single thermal cycle (ΔPEEQ) is used, following the Ferrari expertise. The methodology appears to be well correlated with the experimental evidence, thus limiting the number of tests necessary for the approval of the component.

Effect of the Thermal Mean Stress Value on the Vibration Fatigue Assessment of the Exhaust System of a Motorcycle Engine

<div>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.</div>

Kinetics of precipitation for graphite particle in high nickel ductile iron

In order to prevent premature failure of high nickel ductile iron used for engine exhaust manifold due to thermal fatigue, the precipitation morphology, nucleation and growth mechanism of graphite particles in high-nickel ductile iron were systematically studied by optical and SEM microscopy and the growth kinetic equation of graphite particles was derived. The results show that the precipitation density and average size of graphite particles within the austenite grain of high-nickel ductile iron are 44.1 particles/mm2 and 2.2 µm, respectively, and the precipitation density and average size of graphite particles on the austenite grain boundaries are increased to 76.6 particles/mm2 and 17 µm, respectively. The main nucleation mechanism of graphite particles in high nickel austenitic ductile iron is grain boundary nucleation. The maximum nucleation rate temperature of graphite particles nucleated on grain boundary is 650–850 °C, the fastest precipitation temperature is close to 680 °C, and the time from the beginning to the end of the growth of graphite particles nucleated by grain boundary is about 3400 s. The average size of graphite particles precipitated by grain boundary nucleation can grow to grade 7 (15–30 µm) under the high temperature of 715–805 °C for a long time (over 3400 s), which is beneficial to the thermal fatigue property of high nickel ductile iron. The local temperature at manifold should not be higher than 800 °C under long times.

Multi-branch junction boundary model of an internal combustion engine intake and exhaust manifold system

Multi-branch junctions are commonly used in highly integrated supercharged internal combustion engines. Accurate prediction of flow performance is critical to engine cycle simulation. However, the few studies on this type of junction boundary model focus on incompressible fluid, which leads to insufficient accuracy in predicting compressible flow. In this study, based on a constant-pressure model commonly used to calculate multi-branch junctions, by considering fluid compressibility, we developed a momentum conservation model and a pressure loss coefficient model, respectively, that are tailored to multi-branch junctions. The momentum conservation model accounts for structural parameters such as branch angle and the influence of Mach number, and hence it improved the prediction accuracy. For a certain type of high-power-density internal combustion engine, the maximum simulation error is reduced from 7.58% to 2.47% in the engine performance prediction at the rated speed after using the momentum conservation model. The proposed pressure loss coefficient model was mainly used to compensate for the shortcomings of the momentum conservation model in the multi-branch calculation efficiency reduction, which is more dependent on the pressure loss coefficient database provided by the experiment. The influence of fluid compressibility was also considered. This investigation can provide tailored tools for multi-branch junction performance prediction in different functional simulation scenes.

Effect of deposition of carbon deposits on charge flow in EGR valve in CI engine

The exhaust gas recirculation (EGR) valve regulates the exhaust gas flow between the engine exhaust manifold and the inlet one. This allows the inlet air to warm up, improving fuel evaporation and reducing the combustion temperature of the charge. Such a valve reduces the number of harmful substances in the exhaust gas. The valve sticks when too much sediment builds on the walls of the exhaust system, especially during driving in urban conditions or when leaks in the vacuum or exhaust pipes occur. A faulty valve causes the engine to run unevenly at idle speed and under light loads. The defective EGR valve weakens the inlet manifold capacity, increases combustion, clogging of the particulate filter, damage to the lambda probe. A blocked EGR valve may lead to engine immobilization as a result of the operation of its computerized control system. A model of the EGR valve of a selected diesel engine was developed to determine the velocity distribution of the load flowing in it for different values of the degree of valve opening and the volume of deposits on the valve walls. The volume of accumulated carbon deposits on the walls of the EGR valve was measured using a real engine. Based on the recorded mileage of the vehicle, the assumed average speed of the car, and the driving style of the driver, the intensity of deposition of carbon particles on the walls was estimated.

Design and Fabrication of Exhaust System of Formula Student Car

Abstract— The overall aim of this paper is to refine the design and manufacturing techniques of the exhaust system of FSAE cars. The main objective of this paper is selection of ideal geometry of the 4-cylinder engine (GSX R600) exhaust manifold in terms of optimization of back pressure and reduction in gross weight of the exhaust system. For achieving this, we have considered runner length and diameter, muffler diameter, flow of gases in the exhaust manifold, volumetric efficiency, etc. Softwares used in design and validation are Solid works, Ansys and GT Suite. Keywords— FSAE, Exhaust Runners, Collector, muffler, CFD, 1-D engine simulation, NRC

Thermal and Conjugate Heat Transfer Analysis of Exhaust Manifold of Multi-cylinder IC Engine

The exhaust manifold of multi cylinder IC engine is kept in between the engine block and the catalytic converter. So the exhaust manifold is exposed to very high temperature and care should be taken at the critical zone during the design stage. At several critical zones of the exhaust manifold, large compressive deformations are generated at elevated temperatures and tensile stresses remain at cold conditions. The thermal analysis will help in estimating the deformations and stress concentrations due to thermal loads. Therefore, the main aim of this study is to perform thermal analysis and conjugate heat flow analysis of an exhaust manifold of a multi-cylinder engine. The 3D model is generated using SolidWorks and analysis is carried out using Ansys workbench. Materials like grey C.I., aluminium nitride, silicon nitride, and stainless steel are used in this analysis. The results of total heat flux, directional heat flux and temperature distribution were compared. Silicon nitride material is suggested to be the suitable material for engine exhaust manifolds based on the material mechanical properties and thermal distribution-related thermal stress developed on the exhaust manifold.

Flow characterisation in an exhaust manifold of a single-cylinder internal combustion engine (ICE)

This paper presents an investigation of flow characteristic inside the exhaust manifold that were designed with different bending angle (BA), bending radius (BR) and pipe diameter (Dp ). Five exhaust manifold models were developed and analysed by the computational fluid dynamic (CFD) method. Accordingly, the pressure distribution, velocity streamline and backpressure values were observed. The simulation results showed a different flow pattern for all five models, indicating the manifold design affect the flow characteristic inside the exhaust system. The results demonstrated that the pressure distribution inside the exhaust manifold is influencing its velocity streamline pattern, that directly effecting the outlet velocity of the exhaust gas. From this work, a small bending angle with a short straight pipe has led to a smoother exhaust flow and even exhaust velocity across the model. The results obtained from the simulation can be used as a guide to improve the understanding of the flow behaviour in the manifolds and might be used to improve the manifold design.

Design optimization of exhaust manifold’s length for Spark Ignition (SI) engine through CFD analysis on low-end rpm using Taguchi’s Method

The exhaust system especially the exhaust manifold is an important factor that affects the performance of any SI engine. The most influential boundary condition in the exhaust manifold is backpressure where it is defined as the difference between maximum pressure in the exhaust system and the atmospheric pressure. Higher backpressure was documented to reduce the overall performance of an IC engine and increases its fuel consumption based on previous studies. Even though backpressure could not be removed entirely from the exhaust system, it could be reduced the maximize the engine’s performance. This study aimed to reduce the backpressure in the exhaust manifold of the 115cc SI engine by optimizing its lengths (by taking consideration of the impact of bending angles) through Computational Fluid Dynamic (CFD) analysis and Taguchi’s method. From the results, it was found that the bending angles are more dominant in reducing the backpressure even after the lengths are optimized. It was found that the optimal length configuration reduces the backpressure by 13.56%. Therefore, the outcome of this study shows that the optimal length configuration offers lower backpressure which significantly reduces the harmful impacts on the engine’s performance.

Influences of the dead end on the flow characteristics at the exhaust manifold of a marine diesel engine

A 3D Computational Fluid Dynamics (CFD) model of an exhaust manifold with and without a dead end has been developed to investigate the impacts of its geometry on the flow structure and the pressure distribution within the manifold. The model differs from previously studied models principally for its ability to approach the realistic operating principle of an engine as the modelled exhaust valves of the investigated engine open and close according to the firing order. The experimental results of an exhaust manifold without a dead end has been used to validate the CFD model through the pressure distribution and the flow structure. The outcomes demonstrated that the developed CFD model concurred well with the experimental data. The effects of the dead end on the exhaust manifold were then investigated using the validated CFD model. The study has revealed that the addition of a dead end (i) provides a smoother pressure distribution inside the manifold and increase in the efficiency of the turbocharger and (ii) decreases the pressure inside of the interconnection pipes of cylinders while the exhaust gas discharges. Moreover, the results disclose a smoother discharge of exhaust gases leading to a more effective sweeping of the exhaust gas thorough the cylinder without causing any exhaust backpressure. Furthermore, the dead end reduces the turbulence kinetic energy at the blind end of the exhaust manifold resulting in a decrease of pressure loss within. The abovementioned findings regarding to the flow structure and the pressure distribution within the exhaust manifold improve the efficiency of the engine.

Experimental and numerical study on the characteristics of a penetrating exhaust manifold for low-speed two-stroke marine diesel engine

Penetrating exhaust manifold systems are commonly used in low-speed two-stroke marine diesel engines owing to their potential for energy conservation. However, few studies in the literature have reported on this type of manifold system, and there are few guidelines for optimizing the configuration or predicting the performance via a mean-line model. This study investigates the loss characteristics and flow mechanism of the penetrating exhaust manifold of a low-speed two-stroke marine diesel engine using experimental and numerical methods. The loss is characterized by the entropy production, which indicates a decrease in the energy grade. The results show that the minimum loss can be achieved when the penetration depth and diffusion angle of the manifold are approximately 0.5 and 6°, respectively. Moreover, the loss coefficient is maximally reduced by 14.0 % with penetrating exhaust manifold. The flow field analysis shows that the trend of the flow loss is ‘decrease-increase’ owing to the interaction among three factors: the mixing loss due to the shearing of the injection flow with the main flow, the momentum loss due to the impingement on the bottom of the main pipe, and the separation loss in the branch pipe owing to the flow divergence. This investigation can provide guidance for the configuration optimization and loss modeling of the exhaust manifold for low-speed two-stroke marine engines.