Liquefied Natural Gas As the Next Aviation Fuel

Military aircraft will have advanced capability in maneuverability, weaponry and surveillance while maintaining a low detectability. These advanced capabilities introduce more challenges to the energy management system by increasing both electrical and thermal loads and reducing the options for heat rejection. The aerospace industry has been investigating alternative fuels for aviation fuel supply for environmental, economic and security benefits. Most of the fuels investigated and tested were derived from biomass or other forms of organic supply and waste. Biomass fuels can be interchangeable with jet fuels, but typically do not offer any technical advantages unless modified to withstand higher temperatures. Another fuel option is liquefied natural gas (LNG). At first glance, LNG has environmental, economic and security benefits, but with technical challenges. Technical challenges such as low energy density (MJ/m 3 ) and thermal stability at standard atmospheric conditions have limited the research and development efforts due to hurdles in implementation, such as complexity in fuel tanks, storage, transportation and energy storage density. When considering the aircraft as an entire system and not just focusing on the fuel management system, LNG can provide some benefits. LNG has at least ten times more thermal heat sink potential when compared to jet fuels. A quarter of the heat sink potential is at a sink temperature of 112K. Utilizing thermal cooling capabilities of LNG has the potential to reform the way aircraft are designed. LNG offers a compact and efficient thermal management solution which can reduce subsystem size and weight while reducing energy consumption. The increase in thermal management capabilities will open the door to integrating new technologies on aircraft such as high energy pulsed systems. The work presented in this paper evaluates some of the major challenges and benefits of using LNG as an aviation fuel. Nomenclature