The Thermodynamic Analysis of Optimum Ignition Timing. 4th Report. Relationship between Ignition Timing and Rejected Heat from Power Stroke to Cylinder Wall and Exhaust Gas.

Abstract

The author has previously reported that a work done by a power stroke of Gasoline Engine is written as a function of some factors (ignition timing, combustion duration, engine speed etc.) using a pressure diagram in cylinder which is an approximate solution of energy conservation equation. In this report, the author is going to express an rejected heat to cylinder wall and exhaust gas as a similar function of factors mentioned above as the work done by cycle. The analysis shows that ; (1) a rejected heat to cylinder wall is written as a 3rd order polynomial of ignition timing, and increases with advance of ignition timing. (2) a rejected heat to exhaust gas is also written as a 3rd order polynomial of ignition timing, and increases with retard of ignition-timing. (3) total rejected heat is approximatly expressed as 2nd order polynomial of ignition timing, and has a minimum value at MBT.