Hybrid oxygen enrichment and preheating strategy for performance recovery in ultra-lean micro–trapped vortex combustors

Benzitouni, A, Settar, A, Naouam, B, Azzouz, S and Mansouri, Z ORCID: https://orcid.org/0000-0001-9293-3462, 2026. Hybrid oxygen enrichment and preheating strategy for performance recovery in ultra-lean micro–trapped vortex combustors. Energy Science and Engineering. ISSN 2050-0505

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Abstract

Ultra-lean operation in micro-combustion-based thermophotovoltaic systems offers significant benefits including low pollutant emissions and increased longevity due to reduced thermal stresses, but it is hindered by low thermal performance. This paper numerically addresses the potential of oxygen enrichment and preheating to counteract performance losses in a hydrogen-powered micro-trapped vortex combustor operating under ultra-lean conditions. A Taguchi design of 16 cases was conducted at a fixed equivalence ratio of ϕ = 0.3, varying inlet temperature from 300 to 450 K and O2 levels from 21% to 30%, to evaluate their impact on radiative power, energy conversion efficiency, combustion efficiency, and NOx emissions. Results indicate that excessive enrichment (30% O2) at high inlet temperature (≥ 400 K) leads to flame flashback, establishing an upper safety limit. Within the stable operating region, O2 enrichment substantially improved radiative power by up to 56%, while preheating enhanced radiative efficiency by up to 73%, with both factors exhibiting equal influence on combustion efficiency. However, the use of oxygen-enriched air remarkably increased NOx emissions compared to the baseline case at 21% O2. Moreover, the optimal configuration with Tin = 450 K and XO2 = 0.27 has achieved 41% higher energy efficiency and 99% lower pollutant emissions compared to the lean case at ϕ = 0.8.

Item Type:	Journal article
Publication Title:	Energy Science and Engineering
Creators:	Benzitouni, A., Settar, A., Naouam, B., Azzouz, S. and Mansouri, Z.
Publisher:	Wiley
Date:	27 March 2026
ISSN:	2050-0505
Identifiers:	Number Type 10.1002/ese3.70518 DOI 2600399 Other
Rights:	© 2026 The Author(s). Energy Science & Engineering published by Society of Chemical Industry and John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Divisions:	Schools > School of Science and Technology
Record created by:	Melissa Cornwell
Date Added:	02 Apr 2026 09:06
Last Modified:	02 Apr 2026 09:06
URI:	https://irep.ntu.ac.uk/id/eprint/55498

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