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| Fig. 1: A commercial aircraft being fueled with kerosene. (Source: Wikimedia Commons) |
When examining the difference between the fuels used to power a car versus a plane, it is critical to analyze the fundamental difference in their flash point. The question of "can I put jet fuel in my car to make it run incredibly fast?" seems somewhat entertaining on the surface level, but is shot down immediately by simple aspects of how the respective engines are built to run. Jet engines work fundamentally different than piston engines, and therefore their fuel requirements are drastically different.
The flash point of a volatile material is the lowest temperature needed to evaporate enough fluid to form a combustible concentration of gas. Gasoline has a flash point of -45°F and an auto-ignition temperature of 536°F. [1] Gasoline's aviation fuel counterpart Kerosene holds a flash point of 100°F and an auto-ignition temperature of 428°F. [1] Of course, there are deviations based on the actual composition of the fuel.
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| Fig. 2: Burning of Synthetic Fuel. (Source: Wikimedia Commons) |
With the relatively low flash point of gasoline, it serves the purpose of powering the piston engines in cars. Kerosene, on the other hand, is similar to diesel fuel, yet harder to ignite, requiring a stronger, hotter engine. Kerosene is used in planes as it has a high energy content, is easily transported, remains liquid over a large range of temperatures, and is readily available across the globe. [1] Further, with the high flash point level, it is much harder to accidentally ignite, making it safer in public spaces (such as an airport).
With a much lower flash point, gasoline was easily integrated into cars in the early 20th century, running the relatively temperate piston engines. Kerosene, deemed safer with a higher flash point, vast global accessibility, and potent chemical energy easily slid in as the fuel of choice for planes across the globe.
© Conrad Ukropina. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] Flammable and Combustable Liquids Code, 2012 Ed. (National Fire Protection Association, 2012).
