Thermodynamics Mech3001 - Week 8 - Problem 2 (9.35)

9.35 A six-cylinder, four-stroke, spark-ignition engine operating on the ideal Otto cycle takes in air at 95 kPa and 40°C, and is limited to a maximum cycle temperature of 1300°C. Each cylinder has a bore of 8.9 cm, and each piston has a stroke of 9.9 cm. The minimum enclosed volume is 9.8 percent of the maximum enclosed volume. How much power will this engine produce when operating at 2500 rpm? Use constant specific heats at room temperature.

Answer: 27.6 kW

[jameskrall]

Thanks for the solution! I'm just a bit confused why intake is at state 1. If this were a 4 stroke engine, shouldn't we assume the intake happens at some state 0 at the Top-dead-center volume, and a constant pressure process to state 1 (first stroke)? Then two strokes from 1-2, 2-3, 3-4, and 4-1, and final stroke from 1-0? I understand that the 0-1 and 1-0 processes have zero net work, but I believe the intake of a 4 stroke otto cycle should happen at Top-dead-center.