Combustion Uniformity and Emissions Reduction in a Micro Gas Turbine Powered by UCO-Based Biojet Fuel Blends

Abstract

This study experimentally investigates the impact of bio-kerosene blends derived from used cooking oil (UCO) on the performance and emissions of a micro gas turbine, assessing their suitability as drop-in sustainable aviation fuels (SAFs). Engine tests were performed using Jet-A and UCO-based biojet blends at volumetric ratios of 10%, 25%, 50% and 60% in a fully instrumented and carefully calibrated small-scale turbojet test rig, capturing undiluted emissions as well as detailed performance parameters. Across the full operating range, thrust, fuel consumption, air mass flow, compressor pressure ratio, combustor pressure losses, exhaust gas temperature (EGT) and gaseous emissions (CO2, O2, NOx, CO) were systematically analyzed. Results show that overall engine performance remained effectively unchanged, with observed variations remaining within typical measurement uncertainty. Importantly, increased biojet content correlated with reductions of up to 16% in NOx and 12% in CO emissions, effects linked to enhanced combustion uniformity quantified via circumferential EGT deviation. This work therefore presents the first experimental demonstration of this correlation in a micro gas turbine, alongside the first combustor pressure loss data for multiple biojet/Jet-A blends. The findings clearly indicate that UCO-derived biojet blends up to 60% offer tangible environmental benefits without compromising engine performance, while also providing novel insights into fuel?air mixing effects directly relevant for future SAF deployment.