1. What is Engine Efficiency?

Engine efficiency (η) measures how effectively an engine converts the energy in fuel into useful work. It's expressed as a percentage of the theoretical maximum energy available from the fuel (based on its lower heating value).

2. How Does the Calculator Work?

The calculator uses the engine efficiency equation:

Where:

• \( \eta \) — Engine efficiency (%)
• \( P_{out} \) — Power output (W)
• \( m_f \) — Fuel mass flow rate (kg/s)
• \( LHV \) — Lower heating value of fuel (J/kg)

Explanation: The equation compares the actual power output to the theoretical maximum power available from the fuel being consumed.

3. Importance of Engine Efficiency

Details: Engine efficiency is crucial for evaluating performance, comparing different engines, improving fuel economy, and reducing emissions. Higher efficiency means more work is extracted from each unit of fuel.

4. Using the Calculator

Tips: Enter power output in watts, fuel mass flow in kg/s, and lower heating value in J/kg. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What are typical engine efficiency values?
A: Gasoline engines: 20-30%, Diesel engines: 30-45%, Large marine diesels: up to 50%, Gas turbines: 25-40%.

Q2: What is lower heating value (LHV)?
A: The energy released during complete combustion excluding the heat recovered from condensing water vapor in exhaust.

Q3: How can engine efficiency be improved?
A: Through turbocharging, improved combustion, reduced friction, waste heat recovery, and optimized engine design.

Q4: Does this account for all energy losses?
A: No, this is overall thermal efficiency. Additional losses occur in transmission and other systems.

Q5: What's the difference between brake and indicated efficiency?
A: Brake efficiency uses power at the output shaft, while indicated efficiency uses power developed in cylinders (higher).