INTERNAL COMBUSTION ENGINES (reciprocating)

Geometry

Four Stroke Engines

Two Stroke Engines

For Isentropic Process Air as an ideal gas (room temp.)

Cp = 1.005 [kJ/kg K]

Cv = 0.718 [kJ/kg K]

R = Cp - Cv = 0.287 [kJ/kg K]

k = (Cp / Cv) = 1.4

PV = mRT

OTTO CYCLE (Gasoline)

1-2 Isentropic compression2-3 Constant volume heat addition3-4 Isentropic expansion4-1 Constant volume heat rejection

qin = (u3 – u2) = Cv (T3 – T2) [kJ/kg]

qout = (u4 – u1) = Cv (T4 – T1) [kJ/kg]

r = (Vmax / Vmin) = (V1 / V2)

MEP = Wnet / (Vmax – Vmin) [kPa]

DIESEL CYCLE (Diesel)

1-2 Isentropic compression2-3 Constant pressure heat addition3-4 Isentropic expansion4-1 Constant volume heat rejection

qin = (h3 – h2) = Cp (T3 – T2) [kJ/kg]

qout = (u4 – u1) = Cv (T4 – T1) [kJ/kg]

r = (Vmax / Vmin) = (V1 / V2)

rc = (V3 / V2)

MEP = Wnet / (Vmax – Vmin) [kPa]

DUAL CYCLE

1-2 Isentropic compression2-X Constant volume heat additionX-3 Constant pressure heat addition3-4 Isentropic expansion4-1 Constant volume heat rejection

qin = (ux – u2) + (h3 – hx) = Cv (Tx – T2) + Cp (T3 – Tx) [kJ/kg]

qout = (u4 – u1) = Cv (T4 – T1) [kJ/kg]

r = (Vmax / Vmin) = (V1 / V2)

rc = (V3 / Vx)

MEP = Wnet / (Vmax – Vmin) [kPa]