Evaluation of Non-volatile Particulate Matter Emission Characteristics of an Aircraft Auxiliary Power Unit with Varying Alternative Jet Fuel Blend Ratios

Research output: Contribution to journalArticle


  • Prem Lobo
  • Simon Christie
  • Bhupendra Khandelwal
  • Simon Blakey
  • David W. Raper

Colleges, School and Institutes

External organisations

  • Centre for Aviation Transport and the Environment, Manchester Metropolitan University, Manchester M1 5GD, United Kingdom
  • Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom
  • Center of Excellence for Aerospace Particulate Emissions Reduction Research, Missouri University of Science and Technology, Rolla, Missouri 65409, United States


The aviation industry is increasingly focused on the development of sustainable alternative
fuels to augment and diversify fuel supplies while simultaneously reducing its environmental
impact. The impact of airport operations on local air quality and aviation related greenhouse gas emissions on a life cycle basis have been shown to be reduced with the use of alternative
fuels. However, the evaluation of incremental variations in fuel composition of a single
alternative fuel on the production of non-volatile particulate matter (nvPM) emissions has not
been explored. This is critical to understanding the emissions profile for aircraft engines
burning alternative fuels and their impact on air quality and climate change. A systematic
evaluation of nvPM emissions from a GTCP85 aircraft auxiliary power unit (APU) burning a
16 different blends of Used Cooking Oil (UCO) derived Hydroprocessed Esters and Fatty
Acids (HEFA) type alternative fuel with a conventional Jet A-1 baseline fuel was performed.
The nvPM number- and mass-based emission indices for the 16 fuel blends and neat 100%
UCO-HEFA were compared against those for the baseline Jet A-1 at the three APU operating
conditions. Fuel composition was found to influence nvPM production. The reductions in
nvPM were found to be greater with increasing fuel hydrogen content (higher proportion of
UCO-HEFA in the fuel blend). For a 50:50 blend of UCO-HEFA and Jet A-1, which would
meet current ASTM specifications, the average reduction in nvPM number-based emissions
was ~35%, while that for mass-based emissions was ~60%. The nvPM size distributions were
found to narrow and shift to smaller sizes as the UCO-HEFA component of the fuel blend
increased. This shift has a greater impact on the reduction in nvPM mass compared to the
overall decrease in nvPM number, when comparing the blends to the baseline Jet A-1.


Original languageEnglish
Pages (from-to)7705-7711
Number of pages25
JournalEnergy & Fuels
Issue number11
Publication statusPublished - 19 Nov 2015