Ethanol Bio Fuel

Overview

Engineering reference data for Ethanol Bio Fuel in combustion engineering.

Key Formulas

Heat Release

$Q = \dot{m} \cdot HV$

Fuel energy release rate.

Air-Fuel Ratio

$AF = \frac{m_{air}}{m_{fuel}}$

Mass of air per mass of fuel.

Excess Air

$EA = \frac{O_2}{21 - O_2} \times 100\%$

From flue gas oxygen measurement.

Variables

Symbol	Description	Unit
$Q$	Heat release rate	W
$\dot{m}$	Mass flow rate	kg/s
$HV$	Heating value	J/kg
$AF$	Air-fuel ratio	—

Data Table: Bio-Ethanol Production Yields

Calculations

The ethanol yield per mass of raw material can be converted using the density of ethanol ($\rho_{\text{ethanol}} \approx 0.789$ kg/L at 20°C).

Conversion Formula (Mass to Volume):

$$\text{Yield}_{L/kg} = \frac{\text{Yield}_{kg/kg}}{\rho_{\text{ethanol}}}$$

Energy Content per Volume: The lower heating value (LHV) of ethanol is approximately $21.2$ MJ/liter. The energy yield from a feedstock can be estimated as:

$$E_{\text{yield}} = \text{Yield}_{L/kg} \times \text{LHV}$$

Gasohol Blend Composition: A blend with a volume fraction of ethanol $\phi_{\text{ethanol}}$ (e.g., $\phi = 0.10$ for E10, $\phi = 0.25$ for E25) has a calculated energy content $E_{\text{blend}}$ per liter of blend:

$$E_{\text{blend}} = \phi \cdot E_{\text{ethanol}} + (1 - \phi) \cdot E_{\text{gasoline}}$$

Where $E_{\text{ethanol}} \approx 21.2$ MJ/L and $E_{\text{gasoline}} \approx 34.2$ MJ/L.

Key Properties

• Gasohol: A fuel blend containing gasoline and up to approximately 25% ethanol by volume.
• Feedstock Variability: Ethanol yield per unit land area varies significantly (e.g., from 0.02 to 1.2 L/m²), making crop selection and agricultural efficiency critical for biofuel sustainability.

References

• Original Source