0.8498
849
kg/m³
48.24
MJ/kg
45.38
MJ/kg
40.96
GJ/m³
38.53
GJ/m³
48.24
GJ/t
45.38
GJ/t
4
0.8498
849
kg/m³
48.24
MJ/kg
45.38
MJ/kg
40.96
GJ/m³
38.53
GJ/m³
48.24
GJ/t
45.38
GJ/t
4
The Fuel Properties Calculator estimates the heating values and physical properties of petroleum fuels based on API gravity and sulfur content. The heating value (also called calorific value) is the most important property for energy applications, determining how much thermal energy a fuel releases upon complete combustion. This calculator computes both the Higher Heating Value (HHV), which includes the latent heat of water vapor condensation, and the Lower Heating Value (LHV), which excludes it and better represents the usable energy in most practical combustion systems. These correlations, derived from extensive petroleum product databases, are widely used in refinery energy balances, combustion equipment sizing, fuel purchasing specifications, and greenhouse gas emission calculations across the global petroleum and energy industries.
The Higher Heating Value (HHV) of petroleum fractions is estimated using a correlation based on specific gravity and sulfur content:
$$HHV \approx 51.916 - 8.792 \cdot d^2 + 3.170 \cdot d - 0.01 \cdot S \cdot (4.18 - 0.02S) \quad [\text{MJ/kg}]$$
where d is the specific gravity at 60°F/60°F and S is the sulfur content in weight percent.
The specific gravity is derived from API gravity:
$$SG = \frac{141.5}{°API + 131.5}$$
The Lower Heating Value (LHV) is calculated by subtracting the latent heat of water formed from hydrogen combustion:
$$LHV = HHV - 2.442 \times 9 \times \frac{H}{100} \quad [\text{MJ/kg}]$$
where H is the hydrogen content in weight percent, and the factor 9 represents the mass of water produced per unit mass of hydrogen (since H₂ + ½O₂ → H₂O, with molecular weight ratio 18/2 = 9). The constant 2.442 MJ/kg is the latent heat of vaporization of water at 25°C.
The sulfur correction term accounts for the lower heating value of sulfur compared to hydrocarbon components. Each percent of sulfur slightly reduces the overall heating value because sulfur combustion (S + O₂ → SO₂) releases less energy than carbon or hydrogen combustion.
Typical petroleum fuel HHV ranges from about 42 MJ/kg for heavy residual fuels to 47 MJ/kg for light distillates like gasoline and naphtha. The LHV is typically 5-8% lower than HHV. For comparison, pure hydrogen has an LHV of 120 MJ/kg, while coal ranges from 15-30 MJ/kg. Higher API gravity (lighter fuels) generally produce higher heating values per unit mass due to higher hydrogen-to-carbon ratios. However, heavier fuels have higher volumetric energy density (MJ/L) because their greater mass per unit volume more than compensates for the lower gravimetric energy content.
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Ultra-low sulfur diesel (0.05% S) at 35° API has a higher heating value of approximately 46.0 MJ/kg and lower heating value of 43.1 MJ/kg.
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High-sulfur heavy fuel oil at 14° API has lower heating values per kg but very high volumetric energy density, making it economical for marine and power generation use.
HHV (Higher Heating Value, also called gross calorific value) includes the latent heat released when water vapor from combustion condenses back to liquid. LHV (Lower Heating Value, net calorific value) excludes this latent heat. LHV is the practical energy available in most real systems (engines, turbines, furnaces) where exhaust gases leave above 100°C and water remains as vapor. Condensing boilers can capture some of the HHV-LHV difference.
Lighter petroleum fuels have a higher hydrogen-to-carbon (H/C) ratio. Hydrogen has a combustion energy of 141.8 MJ/kg compared to carbon's 32.8 MJ/kg. Since lighter fuels contain proportionally more hydrogen, their mass-based energy content is higher. However, heavier fuels have higher volumetric energy density (MJ/liter) because the density increase outweighs the specific energy decrease.
Sulfur combustion (S + O₂ → SO₂) releases about 9.3 MJ/kg, which is significantly less than carbon (32.8 MJ/kg) or hydrogen (141.8 MJ/kg). Each percent of sulfur in fuel reduces the HHV by approximately 0.04 MJ/kg. High-sulfur fuels like bunker fuel (3-5% S) have noticeably lower heating values than equivalent low-sulfur grades.
Gasoline typically has an HHV of 46.5-47.5 MJ/kg (LHV 43.5-44.5 MJ/kg) with a volumetric energy density of about 34 MJ/liter. Ethanol-blended gasoline (E10) has slightly lower energy content: about 33.2 MJ/liter, which is why fuel economy decreases slightly with ethanol blends.
The correlations used are accurate to within 0.5-1.0% for standard petroleum fractions derived from conventional crude oil. Accuracy may decrease for synthetic fuels, biofuels, coal-derived liquids, or fuels with unusual chemical compositions. For precise heating values, bomb calorimetry (ASTM D240 or D4809) should be used.
Volumetric energy density (MJ/liter) is the energy per unit volume. While lighter fuels have higher specific energy (MJ/kg), heavier fuels often have higher volumetric energy density. For applications with limited fuel tank volume (vehicles, aircraft), volumetric energy density determines range. Diesel (35.8 MJ/L) provides about 13% more energy per liter than gasoline (31.8 MJ/L).
Hydrogen content can be estimated from API gravity and the universal oil products equation. For petroleum fractions, typical hydrogen content ranges from 10-11% for heavy residual oils to 14-15% for light naphthas. The calculator uses a default of 13% which is appropriate for middle distillates (diesel, kerosene).
Engine exhaust temperatures (300-700°C) are well above the water dew point (~50-60°C for exhaust), so the water formed during combustion remains as vapor and its latent heat is not recovered. Using LHV as the reference energy input gives a more meaningful efficiency value that reflects actual usable energy conversion.
Crude oil typically has an HHV of 42-47 MJ/kg depending on API gravity. Refined products span a wider range: LPG about 49-50 MJ/kg, gasoline 46-48 MJ/kg, diesel 45-46 MJ/kg, and residual fuel oil 40-43 MJ/kg. The refining process separates these components but does not significantly change the total energy content.
Biofuels generally have lower heating values due to their oxygen content. Ethanol has an LHV of 26.8 MJ/kg (about 60% of gasoline), biodiesel (FAME) has an LHV of 37-38 MJ/kg (about 87% of petroleum diesel), and renewable diesel (HVO) has essentially the same heating value as petroleum diesel since it is chemically identical after hydroprocessing.
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