Dear Jeanne, thank you kindly for the great rating :)
Yes, the burn rate of ethanol is affected by environmental conditions such as temperature, pressure, and humidity. These factors influence how quickly the ethanol vaporizes and mixes with air, which in turn changes the combustion characteristics.
Key Factors Affecting Ethanol Burn Rate
Temperature:
Heat (higher temperature): Higher ambient temperatures increase the vapor pressure of ethanol, leading to faster evaporation and a quicker burn rate because more fuel vapor is available to mix with air.
Cold (lower temperature): At lower temperatures, ethanol vaporizes less readily. Below its flash point of around 14°C (57.2°F), liquid ethanol is much harder to ignite and burns more slowly, or not at all in pure form, making cold-weather starting difficult for engines designed for pure ethanol.
Pressure:
Lower pressure (higher altitude): As ambient pressure decreases (such as at higher altitudes), the burning rate of ethanol also decreases. This is due to the lower density of the air, which affects the oxygen available for combustion and the flame propagation speed.
Higher pressure: Conversely, higher pressure generally leads to an increased burning rate and faster combustion duration.
Humidity:
Higher humidity: An increase in humidity (water vapor content in the air) tends to reduce the burn rate. The water vapor acts as a diluent, interfering with the ethanol vaporization and combustion process, which prolongs the combustion duration and can reduce thermal efficiency.
Lower humidity: Lower humidity generally results in a faster burn rate.
Geographic Location:
Geographic location is a proxy for the local climate, which determines the prevailing temperature, pressure (altitude), and humidity conditions. Therefore, the burn rate will vary by location depending on these specific ambient atmospheric conditions.
In essence, these environmental factors affect the rate at which an optimal, flammable vapor-air mixture is created, which is the primary driver of the burn rate
