Calculator Input
Example Data Table
| Fuel | HHV (MJ/kg) | Hydrogen (%) | Moisture (%) | Estimated LHV (MJ/kg) |
|---|---|---|---|---|
| Wood Pellets | 19.00 | 6.00 | 8.00 | 17.49 |
| Bituminous Coal | 28.50 | 5.00 | 10.00 | 27.16 |
| Diesel Fuel | 45.50 | 13.40 | 0.10 | 42.55 |
Formula Used
Primary lower heating value relation:
LHV = HHV − hfg × (9H + M)
Here, H is hydrogen as a mass fraction, M is moisture as a mass fraction, and hfg is water vapor latent heat.
Water formed from hydrogen combustion:
Water from hydrogen = 9 × H
Each kilogram of hydrogen produces about nine kilograms of water during combustion.
Ultimate analysis HHV estimate:
HHV (MJ/kg) = 0.3383C + 1.422(H − O/8) + 0.095S
This is a practical Dulong-style engineering estimate using elemental mass percentages.
Thermal power and annual energy:
Fuel power (MW) = LHV × mass flow / 3600
Annual energy (GJ) = LHV × mass flow × hours / 1000
Useful output applies the selected thermal efficiency to fuel energy.
How to Use This Calculator
- Select whether you already know the fuel HHV or want to estimate it from ultimate analysis.
- Enter hydrogen and moisture carefully because both increase the vaporization energy penalty.
- Keep units consistent. If you choose BTU/lb, enter HHV and latent heat in BTU/lb terms.
- Add mass flow, annual hours, and efficiency to evaluate plant-scale thermal output.
- Submit the form to see LHV, latent heat losses, thermal power, and annual useful energy.
- Use the CSV or PDF buttons to export the calculated engineering summary.
FAQs
1. What does lower heating value represent?
It is the usable heat after subtracting the energy needed to keep combustion water in vapor form. It is often preferred for boilers, engines, and practical combustion studies.
2. Why is LHV lower than HHV?
HHV assumes all water vapor fully condenses and returns latent heat. LHV excludes that recovered condensation energy, so it better reflects many real operating systems.
3. Why does hydrogen reduce LHV so strongly?
Hydrogen forms water during combustion. More hydrogen means more vaporized water and a larger latent heat deduction from HHV to reach LHV.
4. How does moisture affect the result?
Fuel moisture adds water that must be heated and vaporized. Higher moisture raises the latent heat penalty and lowers the usable fuel energy output.
5. When should I use ultimate analysis mode?
Use it when laboratory elemental composition is available but HHV is not. The calculator estimates HHV first, then converts it into LHV.
6. Is the Dulong estimate exact?
No. It is an engineering approximation. It works well for many solid and liquid fuels, but direct laboratory calorimetry remains more accurate.
7. Why include efficiency and operating hours?
They convert fuel properties into practical thermal output and annual energy delivery. This helps with plant sizing, cost estimation, and fuel comparisons.
8. Which unit should I report in projects?
Use the unit common in your site standards. Many engineering studies prefer MJ/kg, while some legacy combustion data still uses BTU/lb.