Advancing Cetane Testing Technologies

The aviation industry is moving towards the achievement of net-zero carbon emissions at an unprecedented rate. The key to this transition is the development and commercialisation of novel Sustainable Aviation Fuel (SAF) technologies. The CFR Ignition Quality Tester (IQT®) has been at the forefront of advances in SAF formulations since their inception.

Jet engine researchers using the IQT discovered that the Derived Cetane Number (DCN) measured by IQT had applications beyond diesel fuel; the DCN of prototype synthetic jet fuels could identify if they were more likely to experience lean blowout than conventional petroleum jet fuels. During a lean blowout event the flame in a jet engine literally blows out: not a good thing while flying! ASTM D4054, the Standard Practice for Evaluation of New Aviation Turbine Fuels and Fuel Additives, is used worldwide to screen candidate SAF formulations for compatibility with conventional jet fuel properties. D4054 requires a DCN value of 35-60 (to avoid lean blowout), and IQT test method D6890 is the only test method recognized by D4054 for this purpose.

In the world of SAF development, potentially game-changing fuel formulations are often initially available only in tiny quantities from research programs. Thus, one critical need for SAF researchers is the ability to conduct the required DCN tests using relatively small sample volumes. The IQT meets this need with the lowest sample volume capabilities in the industry. A full IQT fuel reservoir contains 30 mL of sample, which provides enough fuel for three replicate tests with a typical jet fuel. The IQT fuel reservoir can also be partially filled, and a single D6890 DCN test can be run with only 10 mL of sample.

In ground transportation, the IQT is the leading cetane testing technology for sustainable diesel fuels such as renewable or ‘green’ synthetic diesel. IQT test method EN 15195 is the referee test method for cetane in EN 15940, the European Standard for Diesel Fuels from Hydrotreatment and Synthesis. This standard includes renewable diesel fuel and diesel fuel from Gas-to-Liquids (GTL) processes. The IQT has continually improved since it was adopted by the petroleum industry over 27 years ago, and the latest model, the IQT-XLM, is now in service in North America, Europe and Southeast Asia.

The CFR F5 Cetane Rating System remains the referee test method for petroleum diesel, FAME biodiesel, and petroleum/biodiesel blends. The F5 Engine technology has vastly improved over the

legacy engines that have served the fuel industry for many decades. The F5 Cetane EFI Rating System now brings Electronic Fuel Injection to the ASTM D613 test method, offering substantial improvements in test-to-test repeatability and the ability to test biodiesel without the need for injection nozzle cleaning.

Cetane EFI improves ease of use such that inexperienced operators can quickly learn to achieve consistent results. It is also more suitable for research applications, as full D613 CN tests can now be run with less than 500 mL of sample. ASTM D613 will soon include Cetane EFI as Procedure B of the test method. Procedure B has been approved by the subcommittee responsible for D613, and publication of the revised test method is expected shortly.

Already generating excitement, the first Cetane EFI engine in refinery service was commissioned earlier this year, signalling a new era of precision for the venerable cetane engine.