SMART-HEAT - Surfaces Micro And nanometRically Treated for HEAt Transfer enhancement

Publications

Alternative Liquid Fuels for Aviation Gas Turbines: Experiments and Modelling

Publication . Ferrão, Inês Alexandra dos Santos ; Silva, André Resende Rodrigues; Moita, Ana Sofia Oliveira Henriques; Mendes, Miguel Abreu Almeida

Air transport plays a crucial role in globalization, connecting people and businesses worldwide. Nonetheless, its reliance on fossil fuels significantly contributes to greenhouse gas emissions and pollution. The continuous growth of this sector, alongside the environmental issues and the depletion of fossil fuels, has promoted the investigation of alternative and sustainable energy sources that could supply the aviation industry. Biofuels, drop-in fuels, are considered a promising alternative since they can offer carbon neutrality and substantially further reduction of pollutant emissions, leading to an attractive replacement for conventional jet fuel. Besides reducing dependence on fossil fuel and offering cleaner combustion, many challenges remain regarding biomass availability, process cost, and fuel properties like energy content, viscosity, and volatility. One of the ways to improve the performance of biofuels could be the addition of nanoparticles. This new fuel generation is noted as nanofuels centered on dispersing nanoparticles stably suspended in conventional liquid fuels. In particular, metallic nanoparticles have shown increased fuel energy density, enhancements in combustion rates, reduced ignition delay and fuel consumption, and decreased emissions. According to the previous discussion, the present study investigates the influence of metallic particles on sustainable aviation fuel. This fundamental study initially focuses on nanofuel preparation and stability to address its potential use in real applications. Several preparation approaches are suggested to maintain the stability of nanofuels, particularly for high particle concentrations. Following this, both experimental and numerical investigations are conducted on the combustion of a single droplet, exploring several furnace temperatures, particle sizes, and concentrations. In light of this, the droplet size evolution, disruptive burning phenomena, and potential mechanisms that affect nanofuel combustion are discussed. The experiments conducted in a drop tube furnace suggest that nanoparticle addition promotes the appearance of disruptive burning phenomena regardless of the furnace temperature and particle and size concentrations. In addition, a departure from the D2 -law is noticed, affecting the droplet burning rate. Based on this, the addition of nanoparticles to a liquid fuel is numerically studied. Subsequently, an experimental analysis of the spray under non reacting conditions is performed. An experimental facility was developed using a commercial air-assisted atomizer with external mixing to ease the operation of nanofuels. Imaging and Phase-Doppler Interferometer techniques were used to understand the breakup length, spray cone angle and droplet size, and velocity distributions for several air-fuel ratios. The findings suggest that in terms of single droplet combustion, the addition of nanoparticles possesses a beneficial role, whereas, in atomization, an adverse impact is observed, particularly when the particle concentration is increased. Finally, the development of a laboratory combustion chamber for liquid fuels is discussed. An experimental setup was designed and constructed, which plays a significant role in researching alternative and sustainable fuels.

2025-05-08Doctoral thesis

Open access

Keywords

Surface micro and nano-coatings,Biomimetics,Reverse wettability,Phase-change systems, Engineering and technology ,Engineering and technology/Nano-technology

Funding agency

Fundação para a Ciência e a Tecnologia, I.P.
Fundação para a Ciência e a Tecnologia, I.P.

Funding programme

2º Concurso para Projetos Colaborativos para Programa do Joint Innovation Center for Advanced Materials - 2017
3599-PPCDT

Funding Award Number

JICAM/0003/2017