1. Turbocharging the I.C. EngineGuest Lecture for ME 444 Internal Combustion Engines Dr. Philip S. Keller BorgWarner Inc. Engine Systems Group

2. Outline • Introduction • Turbochargers • Thermodynamic Analysis • Compressor • Turbine • Intercoolers • Benefits • Challenges • New Developments • Conclusions

3. Introduction • History • 1885 and 1896, Gottlieb Daimler and Rudolf Diesel experiment with pre-compressing intake air • 1925 Swiss engineer Albert Buchi develops first exhaust gas turbocharger which increases power output by 40% • 1938 first commercial Diesel truck application by “Swiss Machine Works Sauer” • 1962 first production application of turbochargers in passenger cars - the Chevrolet Monza Corvair and the Oldsmobile Jetfire

4. Introduction • History • 1970’s – first oil crisis and increasingly stringent air emission regulations lead to demands for higher power density as well as higher air delivery. Outcome -> virtually all current truck engines are turbocharged. • 1978 Mercedes-Benz puts the 300 SD into production marking the appearance of the first turbocharged Diesel passenger car • 1994 VW introduces the variable geometry turbo in their TDI Diesel engine significantly improving the transient response of the Diesel engine.

5. Why boost? Definitions Introduction

6. Introduction Power is basically a function of three things: • Air density -> boosting • Swept volume • Engine speed

7. Introduction Types of Boosting Systems Exhaust Gas - Turbocharger Mechanical – Supercharger Main problem with supercharging is the parasitic loss of having to drive the compressor from the engine output shaft. This loss can be up to 15% of engine output.

8. Turbochargers • The vast majority of turbochargers consist of a centrifugal compressor and centripetal turbine mounted on a common shaft Turbine Compressor

9. TurbochargersThermodynamic Analysis • ~30-40% of the fuel energy is released as exhaust gas energy • Area bounded by points 415 is the theoretical energy available. This is sometimes referred to as blowdown losses Ideal cycle pressure-volume diagram for a naturally aspirated engine (Baines, 2005)

10. TurbochargersThermodynamic Analysis Schematic of engine with large exhaust volume (left) and minimal volume (right) (Baines, 2005) Ideal cycle pressure-volume diagram for a turbocharged engine (Baines, 2005)

11. Turbochargers - Thermodynamic AnalysisConstant Pressure and Pulse Turbochargers Constant Pressure Turbocharger • Lower backpressure at higher speeds • Primarily marine and industrial engines Pulse Turbocharger • More efficient use of exhaust energy • Better torque at low engine speeds

12. Turbochargers - Thermodynamic AnalysisPulse turbocharger for multi-cylinder engine • Pulse turbochargers need to have the exhaust piping segregated so that exhaust events don’t interfere with one another

13. TurbochargersCompressor • Consists of three elements • Compressor wheel • Diffuser • Housing • Compressor limits • Surge line • Choke line • Maximum Blade Speed

14. TurbochargersTurbine • Turbines consist of turbine wheel and housing

15. Intercooler Turbocharger TurbochargersIntercooler • Temperatures after the compressor can reach 180 C. Cooling the air can offer a significant performance increase. • Simultaneous improvement in output, fuel economy, and emissions