Analyze fuel energy using hydrogen, oxygen, and moisture. Switch methods for measured or estimated values. Export results, inspect trends, and validate sample fuel data.
These examples are illustrative. They show how hydrogen and moisture reduce usable fuel energy.
| Fuel | HHV (MJ/kg) | Hydrogen (%) | Moisture (%) | Latent Deduction (MJ/kg) | LHV (MJ/kg) |
|---|---|---|---|---|---|
| Methane sample | 55.50 | 25.13 | 0.00 | 5.52 | 49.98 |
| Ethanol sample | 29.70 | 13.13 | 0.00 | 2.89 | 26.81 |
| Wood pellet sample | 19.50 | 6.10 | 8.00 | 3.29 | 16.21 |
Direct HHV to LHV relation
LHV = HHV − hfg × (9H + M) / 100
Here, HHV is higher heating value in MJ/kg. H is hydrogen percentage by mass. M is moisture percentage by mass. hfg is the latent heat term for water vaporization.
Estimated HHV from elemental analysis
HHV ≈ 0.3383C + 1.422(H − O/8) + 0.0942S
This common engineering approximation uses carbon, hydrogen, oxygen, and sulfur percentages. The oxygen correction reduces the hydrogen contribution because some hydrogen is already bonded with oxygen in the fuel.
Supporting relations
Water formed from hydrogen = 9 × H / 100
Total vaporized water = 9 × H / 100 + M / 100
These relations explain why fuels with high hydrogen or moisture usually show a larger gap between HHV and LHV.
Lower heating value shows the useful combustion energy of a fuel when water leaves as vapor. This makes it practical for boilers, engines, burners, turbines, and many real exhaust systems. Chemistry and energy teams use LHV to compare fuels under operating conditions that do not recover condensation heat.
Higher heating value includes the energy released if the water formed during combustion condenses fully. Lower heating value removes that recovery. The gap depends mainly on hydrogen content and initial moisture. More hydrogen creates more water during combustion. More moisture means more water already enters the process and must be heated and vaporized.
Fuel chemistry controls energy density. Carbon increases heating value strongly. Hydrogen also contributes, but some of its energy benefit is reduced when oxygen is already present in the fuel structure. Sulfur adds a smaller contribution. Ash acts as inert material. Moisture lowers practical energy output because part of the released heat is spent handling water instead of delivering process heat.
Use the direct relation when laboratory HHV is known from bomb calorimetry or a trusted data sheet. This route is usually better for reporting and equipment design because it starts with a measured heating value and then applies a transparent vaporization correction.
Use the elemental method when you only know the fuel analysis. It gives a practical estimate for screening, feasibility work, and early combustion studies. It is still an approximation, so laboratory testing is preferred for contracts, compliance, and detailed process guarantees.
Keep all percentages on the same basis. Check if values are as received, dry, or dry ash free. Review moisture carefully. Small changes in water content can noticeably shift usable fuel energy. That is why this calculator also plots moisture sensitivity.
It is the usable heat released by a fuel when water stays in vapor form after combustion. It excludes the heat recovered by condensing water.
HHV includes condensation heat from water in the exhaust. LHV removes that portion, so it is normally smaller for the same fuel sample.
Hydrogen combustion forms water. That water must remain vapor under LHV conditions. The latent heat tied to this vapor is subtracted from HHV.
Yes. Moisture adds mass that does not contribute chemical energy. It also consumes heat during warming and vaporization, which lowers usable output.
Yes. It is useful for screening and quick estimates. For final design, testing, or contractual work, measured HHV is usually more reliable.
Use one consistent basis for all inputs. As received, dry, and dry ash free results can differ noticeably. Mixed bases can distort the result.
No. It is a practical approximation. It works well for many screening tasks, but real fuels can deviate from the estimate.
It helps you see how rising water content reduces LHV. This is useful for fuel selection, drying studies, handling decisions, and process control.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.