11-04-2013, 04:16 PM
Aqueous Aluminum Nanofluid Combustion in Diesel Fuel
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ABSTRACT:
This paper presents a significant chemical reaction of hydrogen combustion during aqueous aluminum nanofluid combustion in
diesel fuel. The results show that hydrogen burns in a diesel engine in the presence of an active aqueous aluminum nanofluid. The nano particles are
made by applying a plasma arc to aluminum nanopowder submerged in water. The average diameter of the aluminum nanoparticles is about 40–60
nm and they are covered with thin layers of aluminum oxide due to the high oxidation activity of pure aluminum. This provides a large contact surface
area with water and high activity for the decomposition of hydrogen from water during the combustion process. During combustion the alumina
serves as a catalyst and the coated aluminum nanoparticles are denuded and decompose the water to yield the hydrogen. The combustion of the diesel
fuel mixed with aqueous aluminum nanofluid shows the following phenomena: total combustion heat increases while the concentration of smoke and
nitrous oxide in the exhaust emission from diesel engine are decreased.
Introduction
Research on the topic of water/diesel mixtures in compression ignition
engines is aimed at fuel conservation and reduction of undesirable
emissions and has been presented in several papers [1–3].
Experiments have shown that the water/diesel emulsion can reduce
the concentrations of NOx, smoke, BSFC, etc. during combustion,
and these results agree with the theoretical prediction [4,5]. Additives
of metal oxide in the water/diesel emulsion are normally used
as the catalyst to activate the molecular bonding of the water/diesel
mixture and produce a chemical reaction [6]. The photoelectrocatalytic
effect for generation of hydrogen from water using metal
oxide, e.g., TiO2, as the catalyst is well known [7].
Recently, scientists and engineers have applied nanotechnologies
to human lives in a wide variety of subjects such as biomedical,
material, computer, and fuel engineering fields. Adding metallic
powder to ordinary fossil fuel usually increases the combustion
efficiency and improves combustion stability, e.g., adding 0.5 %
aluminum nanopowder to a rocket’s solid fuel can improve combustion
efficiency by 10 to 25 % and increase combustion speed by
an order of magnitude [8]. Studies have shown that water can react
with aluminum powder during combustion to generate hydrogen
and hence increase aqueous aluminum fossil fuel’s combustion
heat.
Conclusions
Experimental measurements and analysis of aqueous aluminum
nanofluid combustion in diesel fuel using a single-cylinder engine
for engine performance, exhaust emission, and combustion characteristics
were conducted. The fixed parameters are fuel injection
pressure, injection timing, compression ratio, and geometry of the
combustion chamber. The results show that BSFC for AN+D fuel
is less than the D fuel at lower engine speeds less than 1800 r /min.
The aluminum nanopowder additive mixed in D fuel causes a clear
smoke reduction and for engine speeds less than 1800 r /min the
NOx concentration has also a decreasing tendency. Adding a particular
quantity of aluminum nanofluid to diesel fuel not only reduces
fuel consumption, but also improves the exhaust emission
concentration from the diesel engine.