Investigation of the Soot Formation in Ethylene Laminar Diffusion Flames When Diluted with Helium or Supplemented by Hydrogen

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Energy and Fuels, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/ef401970qA new optical diagnostic technique has been used to measure the spatially distributed temperatures, soot diameters, and soot volume fractions in several different ethylene laminar diffusion flames to investigate the effect of adding hydrogen and helium on the soot formation. The test results show that adding hydrogen increases the flame temperature in all regions, while adding helium does not significantly affect the flame temperature in the reaction region but does increase the flame temperature elsewhere. The flame heights when adding helium and hydrogen can be calculated using the correlation introduced by Roper if the ethylene diffusion coefficient is used. This indicates that the flame height is determined by the diffusion of ethylene molecules when the hydrogen fraction is below 20%. It was also found that either adding helium or hydrogen does not significantly affect the soot diameter but does reduce the soot volume fraction. A total of 20% of helium addition by volume was measured to reduce the total soot number by 19%, while a total of 20% of hydrogen addition reduced the total soot number by 23%. In comparison, replacing the hydrocarbon with hydrogen is much more effective in reducing soot formation. Replacement of 25% ethylene by hydrogen was measured to reduce the total soot number by 66%. Apart from demonstrating the influence of hydrogen and helium on ethylene diffusion flames, these measurements provide additional data for modelers of diffusion flames, especially those with an interest in the formation of particulate matter. © 2014 American Chemical Society

Laminar-buming velocities of hydrogen-air and hydrogen-methane-air mixtures: An experimental study

The laminar burning velocities of hydrogen-air and hydrogen-methane-air mixtures are very important in designing and predicting the progress of combustion and performance of combustion systems where hydrogen is used as fuel. In this work, laminar flame velocities of hydrogen-air and different composition of hydrogen-methane-air mixtures (from 100% hydrogen to 100% methane) have been measured at ambient temperatures for variable equivalence ratios (ER = 0.8-3.2). A modified test rig has been developed from the former Cardiff University 'Cloud Chamber' for this experimental study. The rig comprises of a 250mm length cylindrical stainless steel explosion bomb enclosed at one end with a stainless steel plug which houses an internal stirrer to allow mixing. The other end is sealed with a 120 mm diameter round quartz window. Optical access for filming flame propagation is afforded via two diametrically opposed quartz windows in both sides. Flame speeds are determined within the bomb using a high-speed Schlieren photographic technique. This method is an accurate way to determine the flame-speed and the burning velocities were then derived using a CHEMKIN computer model to provide the expansion ratio. The design of the test facility ensures the flame is laminar which results in a spherical flame which is not affected by buoyancy. The experimental study demonstrated that increasing the hydrogen percentage in the hydrogen-methane mixture brought about an increase in the resultant burning velocity and caused a widening of the flammability limits. This experiments also suggest that a hydrogen-methane mixture (i.e. 30% hydrogen+70% methane) could be a competitive alternative fuel for existing combustion plants. (c) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved

Reduction of Energy Cost and CO2 Emission for the Boilers in a Full-Scale Refinery Plant by Adding Waste Hydrogen-Rich Fuel Gas

[[abstract]]The use of hydrogen-containing fuel in gas turbines and industrial burners can benefit both losses of radiative heat and emission of pollutants. In this study, worthless waste hydrogen-rich fuel gas (RG) was led into a high-pressure boiler or a medium-pressure boiler in the fuel system to partially replace fuel oil (FO) and/or natural gas (NG) in a full-scale petrochemistry plant. Two sets of inlet fuel flow rate ratios were examined to evaluate the reductions of boiler energy consumption and CO2 emission. The result showed that for the high-pressure boiler at a loading of 75%, the usage of NG can be 13 × 106 m3/y less and the CO2 emission can be 2.2 × 104 tons/y lower by changing the inlet FO:NG:RG ratio from 1:1:0 to 1:0.65:0.35. Meanwhile, for the medium-pressure boiler at a loading of 70%, the usage of NG can be cut by 8 × 106 m3/y and the CO2 emission can be 3.0 × 104 tons/y lower by changing the inlet FO:RG ratio from 1:0.2 to 1:0.7. Therefore, the addition of RG has practical benefits on both energy saving and the reduction of greenhouse gas emission

Experimental and theoretical studies on helicopter rotor fuselage interaction

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