Overview
Engineering reference data for Propane Butane Mix in combustion engineering.
Key Formulas
Heat Release
Fuel energy release rate.
Air-Fuel Ratio
Mass of air per mass of fuel.
Excess Air
From flue gas oxygen measurement.
Variables
| Symbol | Description | Unit |
|---|---|---|
| Heat release rate | W | |
| Mass flow rate | kg/s | |
| Heating value | J/kg | |
| Air-fuel ratio | — |
Vapor Pressure Data
The following table shows the gauge pressure (psig) of propane-butane liquid mixtures at various temperatures and composition ratios.
The following table provides the absolute vapor pressure of pure butane.
Component Properties & Design Considerations
- Propane (C₃H₈): More suited to colder environments due to its lower boiling point (-44°F / -42°C).
- Butane (C₄H₁₀): Has a higher boiling point (33°F / 0.6°C), making it more volatile in warmer conditions.
- Evaporation Requirements: Evaporation is not solely dependent on temperature; it requires heat input. Limited heat transfer causes the liquid to cool, reducing the evaporation rate.
- System Design:
- Large Consumers: May require external heat exchangers using hot water, electric heaters, or combustion of the LPG itself to supply the necessary evaporation heat.
- Small Consumers: Rely on heat transfer from the surroundings. Container material is critical: composite containers offer less heat transfer than steel containers and can cause performance issues at lower ambient temperatures.