Experimental investigation of flameless combustion of biodiesel.
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Date
2022
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Abstract
A laboratory-scale combustor was investigated under flameless biodiesel combustion. The biofuel was
used due to its importance as a green fuel substitute for conventional fossil diesel, in order to reduce the
emission of greenhouse gases. The combustor design was based on the phenomenon of internal recirculation, whose intensity is determined by the airflow jet momentum rate through its air intake nozzle.
This investigation is important to identify the physicochemical phenomena that govern flameless
combustion of liquid fuels, in addition to determining the operating parameters of the burner. A pressure
swirl atomizer was used to atomize the biodiesel. The influence of biodiesel temperature and pressure on
the droplet size was investigated. Results show that after a certain liquid pressure and preheating
temperature, the droplet size does not vary. The combustor aerodynamics promoted adequate mixing of
fuel vapor in the vicinity of the droplet interface with diluted oxidant, as a result of high airstream jet
momentum rate, leading to distributed combustion reactions. The experimental results showed that
combustion at high rates of excess air and preheated air fulfilled the typical characteristics of flameless
combustion due to the indistinguishable flame limits, reduced combustion noise levels, absence of soot
emissions and low emissions of NOx and CO, simultaneously. On the other hand, combustion in low
excess air resulted in the stabilization of a bright yellowish flame with high soot emissions together with
a sharp increase in CO emissions. The droplet size has a significant influence on the establishment of
stable combustion. For droplet sizes above 35 mm it was impossible to keep the burning of the biodiesel.
NOx and CO emissions were affected by the excess air and temperature variations.
Description
Keywords
Flameless combustion, Biodiesel, Pollutants emissions, Pressure-swirl atomizers, Biofuel
Citation
SILVA, E. O. et al. Experimental investigation of flameless combustion of biodiesel. Energy, v. 255, artigo 124435, set. 2022. Disponível em: <https://www.sciencedirect.com/science/article/pii/S036054422201338X>. Acesso em: 03 maio 2023.