Experimental study on the impact of carbon nanomaterials on coke formation

Thermal management is a major concern of jet engine development. During flight, engine components reach extreme temperatures as a result of frictional heating due to elevated airflow velocities. In order prevent overheating, jet fuel is used as a coolant to dissipate, or absorb the heat from the engine. As the fuel absorbs the waste heat, the temperature and pressure increases. At temperatures above 325°F, hydrocarbon fuels start to become thermally unstable. Thermal stability is characterized as a fuel’s tendency to form solid deposits on fuel lines, nozzles, intake valves, and other engine components. This process is also referred to as coking, and is driven by complex chemical mechanisms that are triggered by increased temperatures.

This paper outlines an experimental study that was conducted to further examine the coking mechanism. Specifically, a complete experimental setup and procedure was designed to simulate coke deposit formation in a controlled laboratory environment. Fuel was thermally stressed up to 330°C at 10 Bar for approximately 6 hours. Tests were conducted using plain Jet-A fuel and Jet-A fuel with 0.1% carbon nanoparticle and nanotube additives. Results showed that the introduction of nano-additives into the fuel yielded less deposit formation and build up on stainless steel surfaces. A reduction in deposit formation would lead to reduced maintenance costs and improved operation for military and commercial jet engines.