Effects Of Air Inlet Angle On The Combustion And Emission Characteristics Of A Cylindrical Chamber Fueled With Waste Cooking Oil Blends
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Date
2022-07-24
Authors
Ong, Guan Kai
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The scarcity of fossil fuels had greatly prompted a thorough search for alternative
renewable resources. Diesel fuel made of petroleum could be replaced with biodiesel,
an alternative energy source. One of the main constituents in biodiesel fuels is esters
which are made of vegetable or animal fats. They are regarded as effective, healthy, and
natural energy alternatives for fossil fuels. However, vegetable oil or waste cooking oil
(WCO) is less combustible and possess higher viscosity compared with pure diesel.
Larger droplets are generally produced due to the poor atomization quality. These
droplets will burn slowly because of the shorter ignition delay. In addition, poor
atomization characteristics of WCO will lead to poor air-fuel mixing. The poor air-fuel
mixing results in bad performance of combustion and emission. Therefore, swirl motion
is introduced to improve air-fuel mixing by creating an intense turbulent recirculation
zone. The inlet angle affects the air motion inside the combustion chamber. A
cylindrical combustion chamber with two tangential air inlets were created. The effects
of air swirling with tangential air inlet angles of 0°, 10°, 20°, 30° and 45° were
investigated using Ansys Fluent with a model of species transport. The mass flow rate
of air and fuel are the same for all models to compare the effects of swirl motion better.
The temperature and velocity profiles as well as the mass fraction of O2, CO2 and
pollutant NO are comprehensively evaluated. Over the range of tangential air inlet
angles examined, the optimal angle was discovered to be 45°. The combustion chamber
with tangential angle of 45° emitted the least pollutants of NO. Furthermore, it was also
found that kerosene is slightly better than WCO fuel in terms of combustion and
emissions characteristics. The viscosity and cetane number of kerosene is lower than
that of WCO fuel so that it is comparatively poor in atomization and vaporization
characteristics. This phenomenon has resulted in lower emissions of CO2 and pollutant
NO. However, WCO fuel can be an alternative resource of energy as it is renewable and
biodegradable. It also has similar combustion performance with the conventional fuel.