1. Gas law engine Operation of a 4 cycle engine: Google “4 cycle animated Engine” Use the ideal gas law if the number of moles change. The combined gas law and ideal gas law) works if the number of moles do not change. The combined gas law is in the objectives.

2. Gas law engine INTAKE Intake valve (left) opens and piston draws the correct mixture of gaseous fuel and air where T=95 O C P =1.0 atm V = 0.40 L Calculate the moles of gas drawn. NOTE: The number of moles change. Use the ideal gas law. R=0.0821 L-atm/mol-K ANS = 0.0132 mol

3. Gas law engine COMPRESSION At piston lowest point: T=95 O C P =1.0 atm V = 0.40 L V = 0.40 L n=0.0132 mol (last slide). All valves are closed. Piston moves to its highest point where T= 120 O C & V= 0.040 L. (Comp. ratio=10) NOTE: The number of moles do not change. Calculate the pressure at the highest point before ignition. ANS = 10.7 atm

4. Gas law engine Ignition/power Spark plug ignites the fuel: 2C 6 H 14 + 19O 2 →12CO 2 + 14H 2 O + heat Moles in first slide increase by a factor of 1.2 (26/21) to 0.0158 mol. T=450 O C & V = 0.040 L. NOTE: The number of moles change. 1. Calculate the pressure at the highest point after ignition. ANS = 23.4 atm 2. Heat and pressure drives the piston down to where T = 120 o C and V = 0.40 L. NOTE: The number of moles do not change. Calculate the pressure at the lowest point. ANS = 1.27 atm

5. Gas law engine Exhaust Exhaust(right) valve opens. T=120 o C. Piston moves up discharging gases through the exhaust pipe. 1.Why is this process noisy and sound control (muffler) necessary? 2. Calculate the moles of gas left in the cylinder at the highest point where P = 1.0 atm T = 120 o C & V = 0.040 L. ANS = 0.00124 mol 3. What cools the engine from 120 o C back to 95 o C to complete another cycle? What happens if the engine is not cooled?

6. Gas law engine Four cycle engine: Cam shaft – Ignition timing “Animations → “slide show” Timing belt → “From Piston Current Slide.” Press “ESC” When finished. Crank Shaft