Brake Thermal Efficiency Given Brake Power Calculator

Brake Thermal Efficiency Formula:

\[ \eta_b = \frac{BP}{m_f \times CV} \times 100 \]

Brake Power (BP):

Watt

Mass of Fuel Supplied per Second (m_f):

kg/s

Calorific Value of Fuel (CV):

J/kg

Brake Thermal Efficiency (η_b):

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1. What is Brake Thermal Efficiency?

Brake Thermal Efficiency (in %) is defined as the brake power of a heat engine as a function of the thermal input from the fuel. It represents how effectively an engine converts the chemical energy in fuel into useful mechanical work.

2. How Does the Calculator Work?

The calculator uses the Brake Thermal Efficiency formula:

\[ \eta_b = \frac{BP}{m_f \times CV} \times 100 \]

Where:

\( \eta_b \) — Brake Thermal Efficiency (%)
\( BP \) — Brake Power (Watt)
\( m_f \) — Mass of Fuel Supplied per Second (kg/s)
\( CV \) — Calorific Value of Fuel (J/kg)

Explanation: The formula calculates the percentage of fuel energy that is converted into useful mechanical work at the engine's output shaft.

3. Importance of Brake Thermal Efficiency

Details: Brake Thermal Efficiency is a crucial parameter for evaluating engine performance and fuel economy. Higher efficiency indicates better fuel utilization and reduced energy waste.

4. Using the Calculator

Tips: Enter brake power in watts, mass flow rate of fuel in kg/s, and calorific value in J/kg. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical range for brake thermal efficiency?
A: For internal combustion engines, brake thermal efficiency typically ranges from 25% to 40%, with diesel engines generally being more efficient than gasoline engines.

Q2: How does brake thermal efficiency differ from indicated thermal efficiency?
A: Brake thermal efficiency considers power output at the crankshaft, while indicated thermal efficiency considers power developed in the cylinders (before accounting for mechanical losses).

Q3: What factors affect brake thermal efficiency?
A: Compression ratio, air-fuel ratio, combustion efficiency, engine speed, load conditions, and mechanical losses all affect brake thermal efficiency.

Q4: Why is calorific value important in this calculation?
A: Calorific value represents the energy content of the fuel, which is essential for determining how much energy is available for conversion to mechanical work.

Q5: Can brake thermal efficiency exceed 100%?
A: No, brake thermal efficiency cannot exceed 100% as it represents the percentage of fuel energy converted to useful work, and some energy is always lost as heat.