Turbocharging the I.C. Engine Guest Lecture for ME 444 Internal Combustion Engines - PowerPoint PPT Presentation

Turbocharging the I.C. EngineGuest Lecture for ME 444 Internal Combustion Engines

Dr. Philip S. Keller

BorgWarner Inc.

Engine Systems Group

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

• 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

• 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.

Definitions

Power is basically a function of three things:

• Air density -> boosting
• Swept volume
• Engine speed

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.

• The vast majority of turbochargers consist of a centrifugal compressor and centripetal turbine mounted on a common shaft

Turbine

Compressor

• ~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)

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)

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

• Pulse turbochargers need to have the exhaust piping segregated so that exhaust events don’t interfere with one another

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

• Turbines consist of turbine wheel and housing

Intercooler

Turbocharger

• 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