Ice Basic Calculations PDF

Energy Sources and Powertrain Electrification ICE Basic Calculations ©pManifold EV Academy 2 Basic Engine Performance Analysis Terminology Pre...

Energy Sources and Powertrain Electrification ICE Basic Calculations ©pManifold EV Academy 2 Basic Engine Performance Analysis Terminology Pressure Qfuel Pressure BDC BDC TDC Stroke, L θ 0 0° 180° 360° 540° 720° BDC TDC TDC TDC Intake Stroke Compression Stroke Power Stroke Exhaust Stroke Torque Torque Output θ Torque θ 0 0° 180° 360° 540° 720° Torque Torque Consumption Torque Consumption Force on piston = pressure x piston area Consumption = pressure x π d2 / 4 If Total Torque Consumed = Total Torque Output, engine is ‘Idling’ Torque at crankshaft = Force x Stroke / 2 If Total Torque Consumed > Total Torque Output, engine is ‘Braking’ If Total Torque Consumed < Total Torque Output, engine is ‘Driving’ ©pManifold EV Academy 3 Typical Design and Operating Data for IC engines Source: Heywood, “Internal Combustion Engine Fundamentals” ©pManifold EV Academy 4 Combustion and CO2 Every fossil fuel and even most of the bio fuels are hydrocarbons. Combustion chemical reaction of any hydrocarbon fuel is given by the following generic equation… CmHn + (m + n/4)O2 = mCO2 + n/2H2O 78% N2 + 22% O2 16 x 2 x 100 / 22 12 x 1 + 16 x 2 2 x 1 + 16 x 1 145.5 44 18 12 x m + 1 x n (m + n/4) x 145.5 m x 44 n/2 x 18 Petrol (Approximated as Octane) C8H18 + (8 + 18/4)O2 = 8CO2 + 18/2H2O Air:Fuel 12.5 x 145.5 12 x 8 + 1 x 18 Ratio 114 1819 1:16 ©pManifold EV Academy 5 Various Engine Efficiencies Fuel QHV HCV (water in LCV (steam in exhaust) exhaust) Coolant Friction Petrol 46.4 MJ/kg 43.4 MJ/kg Heat Heat Diesel 45.6 MJ/kg 42.6 MJ/kg Fuel Engine Chemical Fuel Heating comb Indicated mech Brake Mechanical Value QHV Work Work Input Output Exhaust Pumping Heat Loss engine Brake Specific Fuel Consumption (BSFC) [g/kWh] or the Fuel Consumed [g] per unit Brake Work [kWh] ©pManifold EV Academy 6 Brake Specific Fuel Consumption & Engine Efficiency Illustrative IC Engine BSFC Contours ηe = 40.6% 4th Gear Brake Mean Effective Pressure (BMEP) 3rd Gear Condition engine 2nd Gear City ~ 10-15% Highway ~ 20-30% ηe = 32.7% ηe = 36.4% 1st Gear Overall ~ 15-25% Engine rotational speed in rpm ©pManifold EV Academy 7 Excel Sheet Calculations of CO2 Emission from Fuel LHV An Excel sheet with cycle operating points in terms of engine torque, speed and fuel consumption rate has been provided. Calculate engine power output, BSFC, and efficiency (engine) for each time step and collate it for city driving, highway driving and overall. ©pManifold EV Academy 8