1. ABE 223: ABE Principles – Machine Systems ABE 223: ABE Principles – Machine Systems Power Measurement Tony Grift Dept. of Agricultural & Biological Engineering University of Illinois

2. Agenda Power measurement Dynamometers, waterbrake, eddy current Torque and Power curve Power computation Pressure-Volume curves Indicated Mean Effective Pressure Power computation in cylinder, engine

3. Power Measurement

4. Belt-driven Prony brake dynamometer.

5. PTO dynamometer Dyno’s Mechanical (friction) Electrical (generator) Hydraulic (water, eddy current) ? What type is this ?

6. Brake Power Measurement Engine Speed Engine Torque

7. Compare Torque in a 430 HP Caterpillar C12 truck and a 437 HP Mustang Cobra. What is the difference?

8. Exercise Compute the Torque of the following vehicles Audi GT Coupe 1985136HP @ 6000 RPM MyHeavyChevy Dodge Viper500 HP @ 7000 RPM DU Sulzer Ships Engine100,000 HP @ 100 RPM Ferrari F1 V12 Engine800 HP @ 18,000 RPM

9. Fig 2.5 Typical diesel engine performance curves

10. Power Computation

11. Physical Model of Mean Effective Pressure F = p* A p Mean pressure in the combustion chamber provides a downward force on each piston.

12. Mean Effective Force of the Stroke A The piston area and the cycle mean effective pressure provide a measure of the average force exerted.

13. Work F = p* A F W = F * L L Simply the average force exerted times the length of the stroke.

14. Power Measurement Dynamometer

15. Power and efficiencies Power in fuel Rejected Heat Friction Power ip Indicated thermal efficiency Mechanical efficiency bp

17. Ideal Otto Engine Simulation Credit: Wolfgang Christian

18. Compression stroke

19. Power stroke

20. Compression and Power Combined

21. Power per Cylinder

22. Power for whole Engine Indicated Mean Effective Pressure during Compression and Power strokes AArea of the piston sStroke of the piston Number of revolutions per second NNumber of cylinders Mechanical efficiency of the engine 2Factor since only 2/4 strokes produce Indicated Mean Effective Pressure (four stroke engine)

23. Homework The indicated mean effective pressure measured in the cylinder is 10 Bar (that is or ). The engine is a V8 four-stroke. The engine is running at 3600 and the mechanical efficiency is 90%. Required: 1) Compute the average Force acting on the piston during the compression/work strokes. 2) Compute the Work being done in one cylinder during compression/work strokes. 3) Compute the work done in 1 second for the whole engine, which is the Power