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Aging and Corrosion Behavior of Ni- and Cr-Electroplated Coatings on Exhaust Manifold Cast Iron for Automotive Applications
Published in B. Sridhar Babu, Kaushik Kumar, Nanomaterials and Nanocomposites, 2021
T. Ramkumar, C. A. K. Arumugam, M. Selvakumar
In the automobile exhaust system, exhaust manifold plays a vital role [1–5]. The exhaust manifold acts as a passage of internally burnt gases from the engine cylinder to the exhaust system. Also the exhaust manifold may get affected by high-temperature gases that are exhausted from the engine. To reduce the high-temperature effects, coating is applied on the exhaust manifold, and in order to avoid this problem, nickel–chromium is coated on the substrate (gray cast iron). The ongoing progress of gas-driven engines for heavy-duty vehicles will further raise the exhaust-gas temperature and make the gas composition more corrosive. The demand was created for both heat and corrosion resistance of the exhaust manifolds. Moreover, materials with high-temperature corrosion resistance and with the ability to withstand the thermal cycling are to be developed. Ferritic ductile cast iron (SiMo51) material is used as a current exhaust manifold that is working at 800°C. At present, many researchers are investigating to enhance the properties of cast iron manifold coated with some dopants such as Nb, Sn, Fe, Ni, and Cr. For exhaust manifolds, one of the most capable approaches to coat the oxidation resistance is electroplating [6].
Intake and exhaust systems
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
The function of the exhaust manifold is to connect the exhaust ports in the cylinder head to the downtake pipe, which leads the exhaust gases to the silencing arrangements. In contrast to the form of intake manifold once associated with a carburettor, the branches of the exhaust manifold are generously proportioned and have large-radius bends of fully streamlined form, which merge as smoothly as possible into the downtake pipe (Figure 7.11a). By offering the minimum resistance to gas flow, an efficient design of exhaust manifold contributes to improved power output from the engine.
Engine systems
Published in Tom Denton, Advanced Automotive Fault Diagnosis, 2020
An exhaust manifold links the engine exhaust ports to the down pipe and main system. It also reduces combustion noise and transfers heat downstream to allow the continued burning of hydrocarbons and carbon monoxide. The manifold is connected to the down pipe, which in turn can be connected to the catalytic converter. Most exhaust manifolds are made from cast iron, as this has the necessary strength and heat transfer properties.
Design and thermal analysis of coated and uncoated exhaust manifold
Published in International Journal of Ambient Energy, 2020
T. N. Valarmathi, S. Sekar, M. Purusothaman, J. Saravanan, K. N. Balan, S. D. Sekar, T. Mothilal
In automotive industries, an exhaust manifold is used to collect and deliver the gases from the cylinders to one pipe. Manifolds are generally fabricated using cast iron or steel. During the process, the manifold is suffered by the heat developed which damages the part. Hence, insulation like thermal spray of ceramic paint or bonding of ceramic mixture or by the use of wrapped manifold is provided for minimizing the heat. Many research works are performed to reduce the consequence of temperature during the process. Mathematical modelling and computational fluid dynamics are applied to analyse the heat transfer in the exhaust manifold (Kandylas and Stamatelos 1999). A complete review is presented about the coating and its effects in diesel engines (Azadi et al. 2013). The effect of temperature on the exhaust manifold is analysed by using CFD software and finite element methodology (FEM) software (Bin Zou et al. 2013). Finite element analysis (FEA) is used to design and analyse the manifold (Gopaal et al. 2014). An exhaust manifold is designed with different coatings and analysed by FEM software CATIA V5 R20 and ANSYS 15.0 (Durga Prasad et al. 2015). The manifold of a 4-cylinder engine is analysed to reduce the stress concentration by CFD and FEA simulation and found that the modification reduces the stress level by 13% (Sahoo and Thiya 2017). To reduce the heat dissipation in the exhaust manifold, different ceramic coatings are performed and analysed (Saravanan et al. 2017).
Design and analysis of exhaust manifold of the spark ignition engine for emission reduction
Published in International Journal of Ambient Energy, 2020
S. P. Venkatesan, S. Ganesan, R. Devaraj, J. Hemanandh
Exhaust gases from the engine cylinders are collected by an exhaust manifold and passed it into one pipe and thrown out into the atmosphere. The pressure required to be developed by the engine to resist or overpower the resistance of the exhaust system in order to discharge the exhaust gases into the atmosphere is known as engine exhaust back pressure. The engine pumps the gas by compressing it to a marginally high pressure to overcome the flow obstructions in the exhaust system. Thus, the engine does the additional mechanical work to compress the exhaust gases to a higher pressure which, in turn, increases the fuel consumption of the engine. The enrichment of mixture supplied leads to the formation of more emissions. Overheating of exhaust valves and deactivation of catalyst in the catalytic converter happen as a result of increased exhaust temperature. Also increased exhaust gas temperature affects the performance of the turbocharger and damages the turbocharger seals, resulting in oil leakage into the exhaust system which affects the performance of the catalytic converter and increases the emissions. All engine manufacturers specify a maximum allowable engine backpressure. If operated at higher backpressure than what is specified by the manufacturer, it can affect the engine. Exhaust velocity is the velocity of the exhaust gases from the outlet of the emission system. They are not produced in smooth streams but are actually generated in pulses. A four-cylinder engine will have four distinct pulses per complete engine cycle. When the number of pulses increases it paves the way for a smooth flow of exhaust gases. Many researchers (Seenikannan, Periyasamy, and Nagaraj 2008; AL-Khishali, Mashkour, and Omaraa 2010 and Ahmed, Kailash, and Gowreesh 2015) have done their research works in this field to reduce the emission from exhaust manifold. Muthaiah, Senthil Kumar, and Sendilvelan (2010) and Naeimi et al. (2011) have analysed and then modified the exhaust manifold using CFD by varying the size of conical manifold with the help of the grid mesh so that it controlled backpressure. Likewise Umesh et al. (2013, 2014) researched and designed eight different manifold designs and classified it as SBCE (Short Bend Centre Exit), SBSE, LBSE (Long Bend Side Exit), etc. and after analysis found out that LBCER (LBCE with reducer) gives the highest overall engine performance and emission reduction. Kanazaki et al. (2002), Han-Chi, Hong-Wu, and Yi-Jie (2012) and Navadagi and Sangamad (2014) analysed the flow of exhaust gas from two different modified exhaust manifolds with the help of CFD. To achieve optimal geometry for the low backpressure they analysed two different exhaust manifolds, base geometry and the modified geometry exhaust manifold. In the modified model of the exhaust manifold, the outlet is at the centre of the exhaust manifold whereas in the base model of the exhaust manifold the outlet is at the side of the first inlet. Two different exhaust manifolds were analysed in the work. After analysis when the results were compared for the two models, it was found that the modified gives low backpressure in comparison with other base models which ensures the improvement in the efficiency of the engine.