Turbochargers - Research Paper Example

Australian Table of Contents List of Figures 3 1Introduction 4 1Aim 4 2Background 4 3Scope & Limitations 4 4Terms of Reference 4 1History& Background 5 2Components 7 2.1Turbine Section 7 2.2Compressor Section 7 2.3Intercooler 8 3Operation and System 9 3.1Turbine Section 9 3.2Compressor Section 9 10 3.3Intercooler 10 4Problems 11 4.1Turbo lag 11 4.2Reliability 11 5Conclusion 12 6List of References 13 Gilles, T. (2012). Automotive service: inspection, maintenance, repairs. New York: Cengage Learning. 13 Appendix 14 0 List of Figures Figure 1: Buchi’s first Turbocharger patent. 5 Figure 2: The internal parts of a typical turbocharger. 6 Figure 3: Turbocharger’s Turbine and Compressor parts 8 Figure 4: Turbine section and Compressor section. The figure show how the turbine section and the compressor sections of a turbocharger works 10 Figure 5: Intercooler Inlet and Outlet tubes. 10 Abstract The need for high performance vehicles is discussed. The focus of this report is to evaluate the origin and development of turbochargers in vehicles as well as identify their role in improving engine performance. Turbochargers origin and development to modern day technologies represent the increasing numbers of high performance vehicle enthusiasts. Additionally, the presence of sophisticated turbochargers is an indicator of not only the will to meet the needs of vehicle users but also that of fulfilling global fuel economy and emission regulations. Despite their short lifespan, turbochargers prove that high performance engines can be achieved. Further, the future of turbocharger application in motor vehicles is bright as turbochargers are made to meet specifications for different nations worldwide. 1 Introduction 1 Aim The purpose of this paper is to understand the invention and role of turbochargers in vehicles. 2 Background Originally, Alfred Buchi invented turbochargers that were commercially intended for application in commercial uses. Further, with the oil crisis of 1973 the benefits of turbocharged engine diesels paid off by fuel saving. Finally, the pollutant legislation reinforcement in the 1980s tightened requiring engines to combat air pollution using turbochargers that are almost in every diesel engine today. 3 Scope & Limitations Since turbochargers are meant to improve car performance, the scope of this research is on promoting a better understanding of the role of turbochargers on engines. Additionally, the role of turbochargers will be understood by evaluating the how performance improvement of cars is attained in comparison to engines with no turbochargers. Since the automobile industry is wide, the research is limited to vehicles and not large motors like ship engines. 4 Terms of Reference Report prepared by: student name Report requested by: instructor’s name When was it requested? Submission Date: 1 History & Background When one thinks of turbochargers, the first impression is appreciation of Alfred J. Buchi who invented the turbocharger in 1905 (Scoltock, 2010). The Swiss Automotive engineer working with Gebruder Sulzer Engine Company and although his invention was prior to the First World War, it was only first patented in 1905. Ten years later, Buchi proposed the first prototype of turbocharged diesel engine that was followed by the firs successful application on two German ships. The ships comprised of a 2,000 hp turbocharged engine each and their success led to the licensing of numerous American, Japan, and European manufacturers. However, Murray-Willat, in 1910, designed the first supercharged engine as a two-stroke-rotation engine and realized that a turbocharger would compensate the issue of reduction in performance. In 1919, General Electric designed a turbocharger on engine aircraft as a test and the result was increase in attitudes. However, Buchi first successfully applied exhaust gas turbocharging in 1925 for the commercial vehicle sector (Miller, 2008). The turbocharger was invented to reciprocate engine using the exhaust energy to elevate fuel-air combination flow thus improve engine performance. Buchi used the turbocharger to ensure that the waste resulting from air-fuel combustion in engines could be routed to the turbine wheel in the turbocharger thus rotating it. Rotating the compressor would then result to compression of the exhaust gas and pumping it into the engine’s chambers. Figure 1 below demonstrates Buchi’s first turbocharger while figure 2 demonstrates the internal parts of a typical turbo charger. Figure 1: Buchi’s first Turbocharger patent. Figure 2: The internal parts of a typical turbocharger. 2 Components Appendix C provides percentage chemical composition of materials found in a turbocharger’s exhaust devices. 2.1 Turbine Section The turbine section of a turbocharger is the primary element of the turbocharger. It is defined as the ‘hot’ side or turbo exhaust. A turbocharger comprises of the turbine housing and turbine wheel (Ralbovsky, 1997). Its main role is to extract energy from exhaust for use in turning the compressor wheel and consequently, ensure sufficient air is supplied to the engine. According to Miller (2008), the turbine in the turbocharger is responsible for converting engine’s exhaust gas into mechanical energy for use in driving the compressor. Turbine wheels exist in continuous, high-velocity jet of exhaust gases of at least 18750F hence, subject to corrosion. Additionally, the turbine rotor is subject to huge tensile loads. The turbine wheels are thus made of nickel superalloys such that they can manage high temperatures and retain high values of strength. The turbine housing is made of cast-iron for strength needed to mount the entire turbocharger to the engine exhaust header (Hartman, 2007). 2.2 Compressor Section The turbocharger compressors are normally centrifugal compressors. They comprise three fundamental components that include compressor wheel, housing, and diffuser (Kane, 2008). The compressor operates opposite to the turbine and draws air in axially; accelerated to high velocity and expelled in radial direction. During its operation, the compressor ingests air somewhat higher than immediate surrounding temperature. However, compressor air can rise substantially with the discharge being about 2050 C. Since the inlet air temperature is low and the fat that much of the temperature rise is in the diffuser, where pressure is acquired from velocity, the compressor wheel’s operating temperature remains way lower than the temperature of the compressor discharge. To withstand cyclic loads at high temperatures, the compressor wheels are aluminum casting especially the permanent-mold blend 354-T61 cast at 2050 which is unknown in any other alloy. Compressor wheels are forged 2000-series aluminum billet. Figure 3: Turbocharger’s Turbine and Compressor parts 2.3 Intercooler As a heat exchanger, the intercooler is device cools fluids between the phases of a multi-staged process of heating. The main cooling activity involves removing surplus heat in a gas compressor thereby reducing the temperature of compressed gas and elevating the density of air delivered to the engine. An intercooler is placed at the front of a vehicle and if front mounting is not possible, it is placed on top of the engine. The best material for intercooler tubes is aluminum. Besides being light-weight, aluminum has mandrel bends and cools much faster than stainless steel. Aluminum is also very easy to cut and trim and can be polished, painted, anodized, or left alone. 3 Operation and System Appendix A shows the turbocharger components and how a turbocharger functions. These are crucial aspects for defining the turbocharger turbine, compressor and intercooler sections 3.1 Turbine Section The exhaust manifold directs exhaust gases from the engine to the vehicle radial-flow turbine and into the turbine housing causing backpressure. When filled with exhaust gas, the turbine housing develops static pressure owing to its volute shape and feeds the turbine wheel inducer area (Hartman, 2007). As high pressure seeks low pressure, the high backpressure and heat in the exhaust gas flow through the turbine wheel and expand causing the rotation of the turbine wheel within the turbine housing. The turbine then extracts kinetic energy as pressure and heat from the exhausts and converts it to mechanical energy through the rotation of the shaft thereby driving the compressor wheel on the intake are of the turbocharger system. For turbocharger effectiveness, efficiency and design are crucial aspects of engine performance, and so are the design enhancements within the turbine. The characteristics of the turbine are determined by throat cross-section such that any reduction in this cross-section causes more exhaust gases upstream elevating turbine performance due to high pressure ratio. Figure 3 indicates the functioning of the turbine section using blue arrows. 3.2 Compressor Section Compressor function uses various thermodynamic principles with the most crucial is the ideal gas law (Appendix B). In turbocharger compressors, the optimum flow efficiency, choke or optimum flow capacity, and surge or a pressure point below which intake air will not flow at a given mass, are specified. The compressor gathers air from raises the pressure prior to entering it to the engine (Gilles, 2012, p. 719). The compressor wheel, a radial compressor, allows air to enter into the wheel’s inducer where it is accelerated, turned 900 and exited perpendicular to the turbine shaft. The energy from the turbine then spins the compressor wheel to pull more air into the wheel for compression. While leaving the compressor, compressed air gets into the diffuser where it is turned into static pressure that fills the compressor cover. From the compressor cover, compressed air is routed through a boost pipe right into the engine. The compressor functions by raising intake pressure to promote engine’s capacity to breath by letting air to completely fill the engine cylinders. Additionally, the compressor increases the density of air for higher boost pressure (Gilles, 2012). The red arrows in figure 3 show compressor working. Figure 4: Turbine section and Compressor section. The figure show how the turbine section and the compressor sections of a turbocharger works 3.3 Intercooler Figure 5: Intercooler Inlet and Outlet tubes. According to Hadfield (2014), intercooler or charge-air cooler is receives hot pressurized air leaving the compressor. The cooler then removes the heat for further improvement of air density as it cools the charge of the intake air. Air from the cooler’s discharge side is then directed to intake valves through a boost tube to the intake manifold of the engine. 4 Problems 4.1 Turbo lag Since turbochargers use centrifugal compressors, rotations per minute (rpm) are required to make a boost. The boost cannot be instant because the centrifugal compressor is driven by exhaust pressure and the acceleration time needed to provide full boost results to delay or turbo lag (Kojima, 2002, p. 126). The solution involves using light materials for the rotating parts of the turbocharger to reduce centrifugal mass. In addition, the design of the impeller and the entire engine combo must be properly designed to reduce the lag. 4.2 Reliability Watson (2009, p. 51) reveals that turbochargers are associated with reliability issues mostly due to limited lifespan and horsepower boost that adds stress to engine components. For instance, rotating shafts that do not receive exceptional lubrication increase changes of turbocharger failure. Additionally, air filtration systems that are poorly installed result to air leakage that can contaminate the turbocharger and destroy it. Turbochargers also lower fuel efficiency of vehicles and result to higher amount of heat wastage. 5 Conclusion There is no doubt that turbochargers boost engine power which is an advantage for vehicle performance enthusiasts. However, including turbochargers in vehicles results to reduction in fuel efficiency and increase in exhaust gases production since more fuel is combusted by the engine to provide the required power. The implication is more fuel consumption which translates to additional costs. Additionally, turbocharger life span affects their reliability and requires frequent servicing of air filter, engine lubricating oil, and oil filter. With the downside of fuel efficiency and higher emissions, turbocharger technologies are seeking to accomplish more stringent world fuel economy and emission regulations as well as customer demands for improved performance and there is a projection of world turbocharger growth by end of 2014 6 List of References Gilles, T. (2012). Automotive service: inspection, maintenance, repairs. New York: Cengage Learning. Hadfield, C. (2014). Automotive engine repair & rebuilding. New York: Delmar. Hartman, J. (2007). Turbocharging Performance Handbook. Minneapolis: Motor books international. Kane, J. (2008, November). Turbochargers. Race Engine Technology Magazine. Kojima, M. (2002). Honda/ Acura engine performance : How to modify D, B and H Series Honda/ Acura engines for street and drag racing performance. New York: HPBooks. Miller, J. K. (2008). Turbo : real world high-performance turbocharger systems. North Branch, MN: Car-Tech. Miller, J. K. (2008). Turbo : real world high-performance turbocharger systems. North Branch: CarTech. Ralbovsky, E. (1997). An introduction to compact and automotive diesels. Albany: Delmar. Scoltock, J. (2010, July 15). Alfred Büchi the inventor of the turbocharger: Turbocharging technology made the combustion engine more reliable and efficient, but the first system barely worked. Aotomotive Engineer, pp. 1-2. Watson, B. (2009). Diesel Performance Handbook for Pickups and SUVs. United States: Motorbooks . Yamataga, H. (2005). The science and technology of materials in automotive engines. Cambridge: Woodhead Publishing Limited. Appendix Appendix A Turbocharger components and how a turbocharger works () Appendix B Ideal gas law Simply, the ideal gas law states that the association between pressure (P), volume (V), and temperature (T) is provided below. Where P = gas pressure V= the volume occupied by the gas T= gas temperature From the equation, pressure is directly proportional to the number of gas molecules and temperatures but inversely proportional to volume. . Appendix C Chemical composition of turbocharger exhausts devices (Yamataga, 2005) Read More