IntermediateTopic 41 of 105Thermodynamics & Fluids
Internal combustion engine performance
Indicated and brake power, mean effective pressure and efficiency.
In depth
Indicated power from P-V diagram, brake power P_b=2πNT; mechanical efficiency=P_b/P_i; brake thermal efficiency=P_b/(ṁ_f·LHV); BMEP=P_b/(V_d·N/2). Specific fuel consumption (g/kWh) compares engines. Volumetric efficiency governs air intake.
Key points
- Compression ratio, bore, stroke
- Torque and power curves
- Emissions regulations
ExampleA 2.0 L engine with 200 N·m at 4000 rpm produces about 84 kW.
What is Internal combustion engine performance?
Indicated and brake power, mean effective pressure and efficiency.
Why is it important to understand internal combustion engine performance?
Engine performance metrics link fuel use to the work an engine delivers, so they guide the choice of engine size and operating strategy.
What is brake power?
The power delivered at the crankshaft, measured on a dynamometer, which is the useful output after friction and pumping losses.
What is brake specific fuel consumption?
The mass of fuel used per unit of brake power per hour, which is a common measure of engine efficiency.
How is Internal combustion engine performance used in practice?
Typical applications include comparing the brake power of two engines for a vehicle, estimating the mean effective pressure to size a new engine and calculating the fuel consumption of a generator set at part load.
What should I learn before Internal combustion engine performance?
Study "Adiabatic flame temperature" first (topic 40 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
What are the key points of Internal combustion engine performance?
Compression ratio, bore, stroke. Torque and power curves. Emissions regulations.
Can you give an example of Internal combustion engine performance?
A 2.0 L engine with 200 N·m at 4000 rpm produces about 84 kW.
What comes after Internal combustion engine performance?
The next topic is "Gas mixtures", which builds directly on this one.
How difficult is Internal combustion engine performance?
It is classed as Intermediate in Thermodynamics & Fluids (topic 41 of 105). It is an intermediate topic. Work through the beginner topics in Thermodynamics & Fluids first.