1. What is Net Calorific Value?

Definition: Net Calorific Value (NCV) means the specific amount of energy released as heat when a fuel undergoes complete combustion with oxygen under standard conditions, excluding the energy contained in water vapor in the exhaust gases.

Purpose: It provides a more accurate measure of usable energy from fuel combustion since the latent heat in water vapor is typically not recovered.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( NCV \) — Net Calorific Value (J/m³)
• \( GCV \) — Gross Calorific Value (J/m³)
• \( WtH_2 \) — Weight Fraction of Hydrogen in fuel
• \( \lambda \) — Latent Heat of Vaporization of Water (kJ/kg)

Explanation: The formula accounts for the energy lost as latent heat when water vapor (produced from hydrogen combustion) condenses.

3. Importance of Net Calorific Value

Details: NCV is crucial for energy calculations in power plants, engines, and heating systems as it represents the actual usable energy from fuel.

4. Using the Calculator

Tips: Enter the Gross Calorific Value (GCV), Weight Fraction of Hydrogen (0-1 range), and Latent Heat of Vaporization (default 2257 kJ/kg for water). All values must be ≥ 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is NCV lower than GCV?
A: NCV is lower because it excludes the latent heat of vaporization of water produced during combustion, which is typically not recovered.

Q2: What's a typical weight fraction of hydrogen?
A: For natural gas ~0.25, gasoline ~0.15, diesel ~0.13, coal ~0.05, but varies by specific fuel composition.

Q3: Why multiply by 9 in the formula?
A: Each kg of hydrogen produces 9 kg of water when burned (8 kg from oxygen + 1 kg hydrogen).

Q4: How do I find the Gross Calorific Value?
A: GCV is typically measured in a bomb calorimeter or provided in fuel specifications.

Q5: What units should I use?
A: Use consistent units - J/m³ for calorific values, fraction (0-1) for hydrogen weight fraction, and kJ/kg for latent heat.