Читать книгу Internal Combustion Engines - Allan T. Kirkpatrick - Страница 66

A single‐cylinder spark‐ignition cycle engine is operated at full throttle, and its performance is to be predicted using a Wiebe energy release analysis. The engine has a compression ratio of 10. The initial cylinder pressure, , at bottom dead center, is 1.0 atm, with a temperature at bottom dead center of 300 K. The bore and stroke of the engine are mm and mm. The total heat addition, = 1764 J, and the combustion duration is constant at 40 degrees. Assume that the ideal gas specific heat ratio is 1.4, the molecular mass of the gas mixture is 29 kg/kmole, and the Wiebe energy release parameters are and .

1 Compute the displacement volume , the volume at bottom dead center, , the dimensionless energy addition , and the mass of gas in the cylinder .

2 Plot the pressure and temperature profiles versus crank angle for −20 (Engine 1) and 0 (Engine 2).

3 Determine the effect of changing the start of energy release from −50 to +20 atdc on the thermal efficiency, and imep of the engine.