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Demonstration of Air-Fuel Ratio Role in One-Stage Turbocompound Diesel Engines
Technical Paper
2013-01-2703
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
A large portion of fuel energy is wasted through the exhaust of internal combustion engines. Turbocompound can, however, recover part of this wasted heat. The energy recovery depends on the turbine efficiency and mass flow as well as the exhaust gas state and properties such as pressure, temperature and specific heat capacity.
The main parameter influencing the turbocompound energy recovery is the exhaust gas pressure which leads to higher pumping loss of the engine and consequently lower engine crankshaft power. Each air-fuel equivalence ratio (λ) gives different engine power, exhaust gas temperature and pressure. Decreasing λ toward 1 in a Diesel engine results in higher exhaust gas temperatures of the engine. λ can be varied by changing the intake air pressure or the amount of injected fuel which changes the available energy into the turbine. Thus, there is a compromise between gross engine power, created pumping power, recovered turbocompound power and consumed compressor power.
In this study, the effects of different λ values and exhaust back-pressure have been investigated on the efficiency of a heavy-duty Diesel engine equipped with a single-stage electric turbocompounding. A one-dimensional gas dynamics model of a turbocharged engine was utilized that was validated against measurements at different load points. Two configurations of turbocompound engine were made. In one configuration an electric turbocharger was used and the amount of fuel was varied with constant intake air pressure. In another configuration the turbocharger turbine and compressor were disconnected to be able to control the turbine speed and the compressor speed independently; then the compressor pressure ratio was varied with constant engine fuelling and the exhaust back-pressure was optimized for each compressor pressure ratio.
At each constant turbine efficiency there is a linear relation between the optimum exhaust back-pressure and ideally expanded cylinder pressure until bottom dead center with closed exhaust valves. There is an optimum λ for the turbocharged engine with regard to the fuel consumption. In the turbocompound engine, this will be moved to a richer λ that gives the best total specific fuel consumption; however, the results of this study indicates that turbocompound engine efficiency is relatively insensitive to the air-fuel ratio.
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Citation
Aghaali, H. and Angstrom, H., "Demonstration of Air-Fuel Ratio Role in One-Stage Turbocompound Diesel Engines," SAE Technical Paper 2013-01-2703, 2013, https://doi.org/10.4271/2013-01-2703.Also In
References
- Hountalas , D. , Katsanos , C. , and Lamaris , V. Recovering Energy from the Diesel Engine Exhaust Using Mechanical and Electrical Turbocompounding SAE Technical Paper 2007-01-1563 2007 10.4271/2007-01-1563
- Ishii , M. System Optimization of Turbo-Compound Engine (First Report: Compressor and Turbine Pressure Ratio) SAE Technical Paper 2009-01-1940 2009 10.4271/2009-01-1940
- Thompson I. G. , Spence S. W. , Thornhill D. , McCartan C. D. and Talbot-Weiss J. M. The technical merits of Turbogenerating shown through the design, validation and implementation of a one-dimensional engine model International Journal of Engine Research October 2012
- Thompson , I. , Spence , S. , McCartan , C. , Talbot-Weiss , J. et al. One Dimensional Modeling of a Turbogenerating Spark Ignition Engine Operating on Biogas SAE Int. J. Engines 4 1 1354 1364 2011 10.4271/2011-01-1144
- Kruiswyk R. The role of turbocompound in the era of emissions reduction 10th International Conference on Turbochargers and Turbocharging 2012
- Hiereth H. and Prenninger P. Charging the Internal Combustion Engine Springer 2007
- Vuk C. T. Turbo Compounding, A Technology Who's Time Has Come John Deere Technical Center 2005
- Hindi , G. , Zabeu , C. , and Langeani , M. Turbocharged vs. Turbo-Compounded Ethanol Engine: Fuel-Air Equivalence Ratio Impact SAE Technical Paper 2009-36-0050 2009 10.4271/2009-36-0050
- Wallace , F. High Output Compound Diesel Engine Schemes - How do they Compare with State-of-the-Art Turbocharged Engines? SAE Technical Paper 952099 1995 10.4271/952099
- G. T. Inc. GT-SUITE Flow Theory Manual 7.3 http://www.gtisoft.com
- Winkler N. Transient simulations of heavy-duty diesel engines with focus on the turbine Licentiate Thesis Royal Institute of Technology Stockholm, Sweden 2008
- Heywood J. B. Internal combustion engine fundamentals McGraw-Hill 1988
- Japikse D. and Baines N. C. Introduction to turbomachinery Concepts ETI, Inc. and Oxford University Press 1995
- Zhuge , W. , Huang , L. , Wei , W. , Zhang , Y. et al. Optimization of an Electric Turbo Compounding System for Gasoline Engine Exhaust Energy Recovery SAE Technical Paper 2011-01-0377 2011 10.4271/2011-01-0377
- Thompson I. , Spence S. , McCartan C. , Thornhill D. and Talbot-Weiss J. Investigations Into the Performance Of A Turbogenerated Biogas Engine During Speed Transients ASME Turbo Expo 2011