Why Do Airplanes Use Kerosene Instead of Gasoline?

Airplanes use kerosene, also known as Jet-A fuel, instead of gasoline for several reasons:

1. Flash Point: Kerosene has a higher flash point of around 38°C than gasoline which is around minus 40°C. The flash point is the lowest temperature at which a fuel can ignite. Kerosene’s higher flash point makes it safer to use in high-altitude, low-pressure conditions, where the air is thinner and the risk of ignition is higher.

2.FreezingPoint: Kerosene has a lower freezing point of around minus 40°C compared to gasoline which is around minus 10°C. At high altitudes, the temperature can drop to minus 50°C or lower, causing gasoline to gel or freeze. Kerosene remains liquid and can flow smoothly through the fuel system.

3. Energy Density: Kerosene contains more energy per unit of weight than gasoline. This means that kerosene provides more power per unit of fuel, which is essential for aircraft engines that need to generate a lot of power to overcome air resistance.

4. Thermal Stability: Kerosene is more thermally stable than gasoline, meaning it can withstand the high temperatures generated by the engine and the friction of the fuel system without breaking down or degrading.

5. Combustion Characteristics: Kerosene has a more controlled combustion profile than gasoline, which is important for jet engines that rely on a precise mixture of fuel and air to produce efficient combustion.

6. Availability and Cost: Kerosene is widely available and relatively inexpensive compared to other fuels. The aviation industry has standardized on kerosene-based fuels, which makes it easier to manage logistics and supply chains.

Let’s break down the main differences between a car engine and a jet engine, and how these differences impact their fuel choices:

Car Engine Also known As Internal Combustion Engine

1. Air, fuel, and spark are mixed inside the engine’s cylinders, igniting a small explosion that drives the piston down.

2. The Compression Ratio is relatively low, around 8 to 10:1

3. The Operating Temperature is Relatively low, around 200 to 300°C.

4. The Power Output is Measured in horsepower, typically around 100 to 200 horsepower.

5. Fuel is pumped from the tank to the engine, mixed with air, and ignited.

Jet Engine Also Known And s Gas Turbine Engine

Air is compressed, mixed with fuel, and ignited in a combustion chamber, producing a high-temperature and high-pressure gas that expands through a turbine, generating thrust.
Its Compression Ratio is very high, around 20 to 30 ratio 1

Its Operating Temperature is Extremely high, around 1000 to 1500°C and with a Power Output Measured in thrust, either in pounds or kilograms, which is typically around 50,000 to 100,000 pounds or 225 to 445 kilonewton.

Fuel is pumped from the tank to the combustion chamber, where it’s mixed with compressed air and ignited.

Key Differences Affecting Fuel Choices

1. Temperature and Pressure: Jet engines operate at much higher temperatures and pressures than car engines, requiring fuels with higher thermal stability and flash points.

2. Energy Density: Jet engines require fuels with high energy density to produce a large amount of thrust, while car engines prioritize fuel efficiency and lower emissions.

3. Flow and Viscosity: Jet engines require fuels with specific viscosity and flow characteristics to ensure smooth operation at high altitudes and low temperatures.

Fuel Choices

Gasoline, otherwise known as petrol or diesel fuel are commonly used, with properties optimized for internal combustion engines.
Jet-A1, a type of kerosene or Jet-A fuel are used, with properties optimized for high-temperature, high-pressure, and high-energy-density applications.

The differences in engine design and operation lead to distinct fuel requirements. Gasoline and diesel fuel are suitable for car engines, while Jet-A1 and Jet-A fuel are designed for the extreme conditions of jet engines.