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Reciprocating Engines
Published in Neil Petchers, Combined Heating, Cooling & Power Handbook: Technologies & Applications, 2020
The piston is fitted with rings, which ride in grooves cut in the piston head to seal against gas leakage and control oil flow. The compression rings make the piston and the cylinder walls airtight by sealing the space between the piston and the liner. Oil rings, which are located below the compression rings, prevent surplus oil from being carried up into the combustion chamber where it would burn incompletely and form carbon. They are designed to scrape off, on the down-stroke, most of the lubricating oil splashed into the cylinder and return it to the crankcase and ride over the remaining oil film on the way up. The crankcase must be ventilated to remove gases that blow by the piston rings to prevent pressure build-up.
Engine lubrication
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
Since the gases escaping from an engine with open crankcase ventilation contribute to air pollution, modern practice demands a positive closed system of ventilation, so that pollution from cylinder blow-by gases becomes negligible. Positive crankcase ventilation (usually abbreviated by PCV) was originally conceived by General Motors in America, where it was recognized in the early 1960s that cylinder blow-by gases could account for perhaps 20 per cent of the harmful emissions from a vehicle engine and its fuel system.
A review of computational studies on the effect of physical variables in direct injection diesel engines
Published in Australian Journal of Mechanical Engineering, 2023
The concept that engine design is all important in the use of vegetable oils as a dual fuel along with diesel has been pointed out by many researchers. One hundred percent of vegetable oil can be used safely in an indirect injection engine, but not in a direct injection engine due to the high degree of atomisation required for this type. This problem is related to increasing droplet size on injection into the cylinder that results in poor combustion. This in turn, causes the formation of deposits in the combustion chamber, together with oil dilution due to introduction of unburnt fuel into the crankcase. The effect of increasing the fuel inlet temperature on viscosity and performance of a single cylinder, unmodified diesel engine is an interesting observation as the flash point and fire point of the fuel seems to avoid experimental task involved. Fuel heating studies could show the behaviour of peak cylinder pressure that may be beneficial at low speed under part-load operation.
Numerical analysis of modified crossbreed engine cycle under BS VI norms
Published in International Journal of Ambient Energy, 2022
P. V. Elumalai, M. Parathasarathy, S. Sathishkumar, M. Murugan, A. Saravanan, M. Sreenivasa Reddy, Keerty Venkata Sri Ramachandra Murthy
Instead of using crankcase compression as in the conventional two-stroke engine, wet-sump lubrication was placed to maintain the engine’s operating temperature within the range. This proposed engine works on fuels with different octane values and also on biofuels due to the variable compression ratio and air-fuel mixture by controlling the airflow during suction. The introduction of electronic components tends to operate the engine with more accuracy even at high-speed conditions with minimal errors. The operation of a two-stroke cycle increases the engine’s overall efficiency up to 80% with a higher power-to-weight ratio. Owing to complete electronic operation, this engine has an additional advantage. It can be finely tuned by adjusting the inputs and processing structure, which enables the engine to operate under two- and four-stroke engine cycles.
Multi-parameter detection of 4 years and coupling analysis of lubricating oil for tugboat engine
Published in Ships and Offshore Structures, 2022
Geng-Shuo Liu, Xin-He Zhu, Cheng-Di Li, Yun-Yang Fu, Shao-Wei Shang, Zhuo-Kai Zhang
Flash point, fuel dilution, and water content. The water content in the lubricating oil system of this tugboat is relatively stable (Figure 10). The fuel dilution shows an upward trend (Figure 11), and the flash point shows a downward trend (Figure 12). For lubricating oil, there is some correlation between flash point, fuel dilution, and water content, which affects each other. When the fuel dilution increases, it shows that the fuel oil is entering the lubricating oil system. That will lead to the lubricating oil more flammable, which will inevitably lead to the decrease in the flash point of the lubricating oil. The increase in water content in lubricating oil will lead to the increase in lubricating oil flash point. The water content in the lubricating oil is relatively stable. According to the rising trend of fuel dilution, it can be determined that the piston ring–cylinder liner friction pair has abnormal wear. The fuel in the combustion chamber enters the crankcase through the wear surface of the piston ring–cylinder liner. This leads to the continuous increase in the fuel dilution and obvious downward trend of flash point. However, the overall fuel dilution is below 2%, which is within the normal range. Just pay a little attention to the wear of the piston ring–cylinder liner.