Thermal characteristics and emissions of gaseous fuel flameless combustion with tangential air inlet
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Date
2014
Authors
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Publisher
Universiti Teknologi Malaysia
Abstract
Flameless combustion is one of the most important achievements of the combustion technology in recent years. The flameless combustion is of great interest; it simultaneously provides higher thermal efficiency together with controlled pollutant emissions. In this work, specially designed low NOX flameless combustor has been developed at the High Speed Reacting Flow Laboratory (HiREF), Faculty of Mechanical Engineering, Universiti Teknologi Malaysia (UTM) to reduce the pollutant emissions and increase the thermal efficiency. The objective of this study is to reduce NOX emission and to increase thermal efficiency as compared with conventional combustion. The HiREF flameless combustor is unique in terms of its preheating method by means of channeling fresh air through a helical tube that was fixed inside the combustion chamber. The hot air was then injected back for most of the flameless combustion experiments. The main objective of this study is to investigate in detail the role of air inlet geometry on the performance of flameless combustor. The enhancement of the performance of the flameless combustion is evaluated with natural gas and propane with different concentrations of CO2 that is used as dilution. The NOX emission is reduced during flameless combustion due to temperature uniformity inside the combustion chamber. The results show that NOX emission was recorded to be 8 ppm or lower under different operating conditions of flameless combustion mode. In addition, there is an increase in thermal efficiency up to 49.4%. In this study, a uniform combustion chamber temperature is recorded and this is the main characteristics of this flameless combustion technology. The geometry of the inlet air has a strong influence on pollutant emissions and the performance of flameless combustion. The major finding of this study is that using tangential method produced around 2 ppm lesser NOX emissions than a coaxial method for air entry under different operating conditions. This was due to the good mixing between the air, fuel and diluted gas
Description
Thesis (Ph.D (Mechanical Engineering))
Keywords
Nitrogen oxides—Environmental aspects, Flame, Combustion