An internal combustion engine can be described according to the following idealized cycle, where air is considered to be the working substance and is assumed to behave ideally with CP,m = (7/2)R.
(1) reversible adiabatic compression from A to B (piston stroke)
(2) reversible constant-volume pressure increase from B to C due to the combustion of a small amount of fuel.
(3) reversible adiabatic expansion from C to D (piston stroke)
(4) reversible and constant-volume pressure decrease back to state A. Use a compression ratio of 10:1. Take state A to be VA = 4.00 L, pA = 1.00 bar, and TA = 500 K. Assume that VA = 10VB and pC/pB=5.
(a) Determine the changes in entropy (of the system, the surroundings, and the universe) for each step of the cycle and the cycle overall.
(b) Evaluate the maximum efficiency of the engine, assuming that the heat is supplied in step (2).