Discuss About The Diesel Engine Performance Bearing Friction?
Friction within the engine equipment is affected by the ratio between the stroke and the bore because of two opposing effects. These are the friction at the crankshaft bearing and the friction at the power cylinder. An increase in the bore-to-stroke ration causes an increase in the comportment friction as the larger piston area transfers loftier forces to the crankshaft demeanors. The corresponding shorter stroke results in the decreased power cylinder friction originating at the ring or cylinder interface (Allmaier, et al., n.d.). Frictional forces are undesirable and they lower the performance of the engine. The engine designers are actively improving the lubrication models of the engine to ensure near to or absolute frictionless operations within the engine. Friction is not a desirable occurrence in any process. It causes loss in power and wear and tear of the equipment parts. The engine or automotive structure operates on hydraulic pressure in some sections. At the piston section, a lot of friction is bound to occur. Proper lubrication seeks to solve the issues that are imminent in such auto motives.
All nations especially in the America and Europe continents are adopting the ‘Go Green’ initiative. They have different policies in place to effect this and one of the key policies is the introduction of the limit for the average carbon monoxide emissions for all vehicles available in the marketplace. The common road transport system is estimated to cause approximately 89 percent of the cumulative CO2 emissions. Implementing the policies has resulted in a decrease in the industrial emissions though there is a rising demand for energy in the automotive industry. There are more policies developed by the law makers in the government that are aimed at the fuel consumption and economy as well as the emission of harmful by products into the air and on land (Mufti & Priest, 2009)The loads on the bearings vary significantly with crank angle, the connecting rod geometry and the combustion gas pressure. The indicative pressure profile during compression (Priestner, et al., 2012),
The oil in the engine seals main function is to prevent dripping, serious difficulties result from malfunction of the engine oil seal (Kim & Jeon, 2008). Engines that run on diesel have recently been applied in most heavy-load itinerant and in many motionless units for generating the power. This owes to the fact that they can lead to greater efficacies and complex indicated mean effective pressures, IMEP. The IMEP occurs due to higher compression ratios where they operate (Rostami, et al., 2014).
The engine performance is determined majorly by the fuel consumption and the frictional forces affecting the engine. The biodiesel is the maximum popular alternative fuel. The procedure of the biodiesel is increasing day by day. All things pertaining the biodiesel on internal combustion engines must be known. The quivering effect of canola and sunflower biodiesels at different engine speed was investigated in longitudinal, vertical and lateral axes. Some of the chief engine companies have stated formally that the use of blends that will not void their parts and workmanship warranties. This contains blends below minimum biodiesel, such as the least biodiesel assortments that are becoming more common (John, 2013). Catalytic converters have carbon problems in the original diesel but they do better with the biodiesel. The carbon monoxide emissions result when the gasoline is not completely burned and the oxides of nitrogen are produced when the combustion temperatures are way too high. The carbon dioxide and oxygen are used to diagnose combustion problems and the gas is classified as a greenhouse gas (Cheng, 2008). The lower exhaust emissions are factored in when the engine design, fuel and ignition system controls, and devices designed to control emissions are considered (Banapurmath, 2008). The catalysts cause chemical reaction without changing their state. The chemical reactions only tend to occur in the presence of a catalyst or they occur faster due to the introduction of the catalyst.
There are several sources of friction in the internal combustion engines and the friction test rigs are used to determine these sources. There is a lot of friction at the piston liner contact. This contact point is felt to account for the larger part of friction in the engine while the journal bearings in the crank train account for the other percentage. The valve train is another major source of friction and it causes the losses that equally accounts for power losses as well as its counterpart, the journal bearings. Lubrication is one of the solutions at the metal to metal contact points. There are several mechanical losses that are involved in the important functions (Zhang, 2002). Generally, friction is a force that occurs between two surfaces that are sliding or slipping across one another. It always works in the opposite direction of work. The effects of friction tend to slow down a moving object. The amount of friction experienced depends on the materials from which the two surfaces are made. When the surfaces are very rough, much more friction is felt than when there are smoother surfaces. Frictional forces have a by-product, heat. Excessive heat in an engine does more harm than good especially when it is not contained. Lubrication using oil tends to reduce friction between two surfaces that are in contact. This implies lesser wear on the metal and minimal heat is produced from the moving parts.
Work consumed by compression process,
The total work per cycle for each section of the engine, I, of the total friction is given by assimilating the friction force, F, times its dislocation dx around the cycle,
The friction force mechanisms are either autonomous of speed or comparative to speed or its square.
To review the frictional impact on the diesel engine performance the following setup was achieved by turning the internal combustion engine over. The turnover was done with the help of the combustion using an induction motor. The system utilizes a belt drive system of about 6000rpm. There is a torque meter that measures the torque of the engine at the beginning of the motor rotation. Indicated mean effective pressure (IMEP) in bar was computed after measuring in cylinder combustion pressure signals for each operating point by using a MATLAB program (Daniels, 2000). Indicated power (IP) in kW was calculated from measured IMEP and brake power (BP) in kW was measured from engine dynamometer. Friction powers (FP) in kW for operating points were then calculated by subtracting brake power (BP) from indicated power (IP), under steady state conditions for both engine lubricants. Variation of oil viscosity with temperature may be neglected since all experiments were conducted in a controlled temperature of oil and coolant (Kim, et al., 2006).
An empirical relation for predicting friction power (FP) of the engine based on the significant factors. It is important to note that in the above empirical equation, the input values for speed in rpm are to be divided by 100; e.g., 1000 rpm is to be put as 10 and input values of load are to be divided by 10; e.g., 50 Nm is to be put as 5. It is noteworthy to state that predicted friction power values for both engine lubricants are very close to the experimental values (Zweiri, et al., 2000). There is lack of the validation caused by the difficulty of measuring parameters straight from the engines running under fired conditions. The friction of the engine bearing section is measured under a wide range of operating conditions of the engine. There is a specially designed camshaft belt drive pulleys are incorporated to measure the friction and the torque of the engine. There are little or no modifications performed on the engine valve train layout is required. (Devendra, et al., 2014). The friction measurement methods include,
Several models have been adopted over the years as research is progressed by different researchers. The Willan’s line model is a clambering procedure that is involved to create the numerical models of IC Engines of almost any desired size. The model provides a good pseudo-static representation of the fuel productivity of CI/SI engines. One of the major advantages of the model is that it is scalable within contraptions of a certain class (Qianfan, 2011). The EGR valve is controlled by input signals of engine temperature and load as the vehicle speed signal or PRNDL switch. Control emission of gasoline vapors from tank. Activated charcoal store gasoline vapors until they are drawn into the engine and burned. Emission of fuel vapors is controlled by sealing the fuel system (Graboski, 2003). Gasoline tanks allow for fuel expansion of umpteenth percent and the expansion dome and liquid or vapor separator, the expansion tank, the filler neck design, and the gas caps sealed or have pressure vacuum valve.
Conclusion
In a nutshell, as little as possible exposed surface area on the combustion chamber and the top of piston has common modifications and the engines run with higher cooling system temperatures. Advancing the ignition timing is good for improved engine performance and the domestic diesel light trucks and vans are now using urea selective catalyst reduction.
References
Allmaier, H., Priestner, C., Sander, D. E. & Reich, F. M., n.d. Friction in Automotive Engines. [Online]
Available at: https://dx.doi.org/10.5772/51568
Banapurmath, N. R., 2008. Experimental Investigations of a four-stroke single cyclinder direct injection diesel Engine operated on dual fuel mode with producer gas as inducted fuel and Honge oil and its methyl ester (HOME) as injected fuels. Renewable Energy, Volume 33, pp. 2007-2018.
Cheng, C. H., 2008. Comparison of emissions of a direct injection diesel engine operating on biodiesel with emulsified and fumigated methanol. Fuel, Volume 87, pp. 1870-1879.
Daniels, C. C., 2000. The Transient Behaviour of Friction components in an Internal Combustion Engine. PhD Dissertation, University of Akron, Akron, OH.
Devendra, S. et al., 2014. Prediction and Analysis of engine Friction Power of a Diesel Engine Influenced by Engine Speed, Load, And Lubricant Viscosity. New York: s.n.
Graboski, M., 2003. The Effect of Biodiesel composition on engine emissions from a DDC series 60 Diesel Engine, s.l.: NREL SR-510-31461.
John, D., 2013. Manufacturere warranty information. [Online]
Available at: https://www.biodiesel.org/resources/fuelfactsheets/standards_and_warranties.shtm#statements
Kim, H. G. & Jeon, S. I., 2008. Effect on friction of engine oil seal with engine oil viscosity. International Journal of Automotive Technology, Issue 9, pp. 601-606.
Kim, H. G. et al., 2006. Experimental study on behaviour characteristics in crankshaft oil seal. s.l., Spring Conference Proc. Korean Society of Automotive Engineers.
Mufti, R. A. & Priest, M., 2009. Theoretical and experimental evaluation of engine bearing performance. Journal of Engineering Tribiology, Part J: Proceedings of the Institution of Mechanical Engineers, Issue 223, pp. 629-644.
Priestner, C., Allmaier, H., Priebsch, H. & Forstner, C., 2012. Friction in highly loaded journal bearings. MTZ, Volume 4, pp. 310-315.
Qianfan, X., 2011. Diesel engine system design. 1st ed. s.l.:Woodhead Publishing in Mechanical Engineering.
Rostami, S., Ghobadian, B. & Kiani, M. K. D., 2014. A Diesel Engine using Diesel-Biodiesel Blends. International Journal of Automotive and Mechanical Engineering: Kuantan, Volume 10, pp. 1945-1958.
Zhang, C., 2002. TEHD behaviour of non-newtonian dynamically loaded journal bearings in the mixed lubrication for direct problem. Journal of Tribology, Volume 124, p. 178.
Zweiri, Y. H., Whidborne, J. F. & Seneviratne, L. D., 2000. Instataneous Friction Components Model for Transient Engine Operation. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, Issue 214, pp. 809-824
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