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Internal Combustion Engines
Published in Iqbal Husain, Electric and Hybrid Vehicles, 2021
The valve arrangement in the cylinder is known as the valve train. The valve train can be overhead valve (OHV), single overhead cam valve (SOHC) or dual overhead cam valve (DOHC). The OHV has camshaft, push rod, rocker and valve, while the SOHC and DOHC have camshaft(s), rocker and valve. The SOHC has one camshaft placed in the cylinder head, while DOHC has two camshafts in the cylinder head, one for the inlet valves and the other for the exhaust valves. There can be 2, 3, 4 or 5 valves in a cylinder. The number of valve selection depends on the tradeoff between flow and complexity.
Engine systems
Published in Tom Denton, Automobile Mechanical and Electrical Systems, 2018
A further development, now employed extensively, is the use of twin or double overhead camshafts (DOHC) (Fig. 2.100). These can use direct or indirect valve actuation and are well suited to multivalve engine designs, including those with variable valve timing.
Progress in regulated emissions of ethanol-gasoline blends from a spark ignition engine
Published in Biofuels, 2021
Amit Kumar Thakur, Ajay Kumar Kaviti
Schifter et al. [33] investigated the effect of using gasoline-ethanol mid-level blends (0–20% ethanol; E6, E10, E15, E20) on exhaust emissions of a single-cylinder AVL model 5401engine, spark ignited and electronically controlled with DOHC(Dual overhead camshaft). Engine tests were conducted for different lambda values and exhaust emissions were analyzed for carbon monoxide, unburned hydrocarbons and nitrogen oxides. As depicted in Figure 11, the highest calculated reduction in emissions was 52% and 19% for CO and HC, respectively, with a corresponding increase of 60% in NOx emissions for the 20% ethanol fuel with respect to the reference fuel. For the interval of lambda values considered (0.9 < k 6 1.1), 20% ethanol fuel showed an average reduction of 13.6% in CO contents, while an increase in hydrocarbons and nitrogen oxides of around 5% was observed. The fuel with 15% ethanol shows the same trend, with reductions of 7.4% in CO. Fuels with 10% ethanol content or less showed almost no change in emissions.
Comparative analysis of combustion dynamics using three reaction source models
Published in Australian Journal of Mechanical Engineering, 2023
Lucky Anetor, Edward E. Osakue, Christopher Odetunde
The OpenFOAM computational fluid dynamics code was used to investigate the performance of three combustion models, namely, Muppala, Zimont and Algebraic. The performance characteristics of these models were tested in a fully premixed modern, high-performance 4-valve, iso-octane dual overhead cam (DOHC) engine with quasi-symmetric pent roof combustion chamber running at 1500 revolutions per minute. The performance characteristics of the three combustion models were found to be reasonably representative of measurement data that are usually observed in internal combustion engine test bed experiments.