203 research outputs found
Measurements of laminar flame speeds of acetone/methane/air mixtures
The effect of acetone on the laminar flame speed of methane/air mixtures is investigated over a range of stoichiometries at atmospheric pressure and room temperature. The liquid acetone is vaporised and seeded into the methane/air mixture at 5%, 9% and 20% of the total fuel by mole. The experiment is performed using the jet-wall stagnation flame configuration and the particle imaging velocimetry (PIV) technique. Laminar flame speeds are derived by extrapolating the reference flame speed back to zero strain rate. Experimental results are compared to numerically calculated values using a base methane chemical kinetic mechanism (GRI-Mech 3.0) extended with acetone oxidation and pyrolysis reactions from the literature. The experimental results show that acetone addition does not affect the laminar flame speed of methane significantly within the range of concentrations considered, with a stronger effect on the rich range than under fuel-lean conditions, and that the peak laminar flame speed of acetone in air is ~42.5 cm/s at ϕ = 1.2. Simulation results reveal that the most important reactions determining acetone laminar flame speeds are H + O2 → O + OH, OH + CO → H + CO2, HO2 + CH3 → OH + CH3O and H + O2 + H2O → HO2 + H2O. Comparison of the expected disappearance of acetone relative to methane shows that the former is a good fluorescent marker for the latter
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Combustion characteristics of alternative liquid fuels
Envisaged application of biodiesel in gas turbine engines or furnaces requires extensive tests on the deflagration properties of biodiesel. The laminar flame speeds of Palm Methyl Esters (PME) and blends of PME with conventional fuels are determined using the jet-wall stagnation flame configuration. The same technique is also used to measure the laminar flame speed of diesel, Jet-A1, n-heptane, acetone, methane and methane/acetone. The spray atomization characteristics of a plain-jet airblast atomizer are investigated using a phase Doppler anemometry (PDA) under non-reacting conditions. The droplet size and velocity distribution of biodiesels are compared to conventional fuels. For spray combustion investigations, a generic gas turbine-type combustor is developed to compare the spray flame established from PME, rapeseed methyl esters (RME), diesel, Jet-A1 and biodiesel blends. The spray droplet
characteristics in the flame and the flow field in the combustor are investigated. Chemiluminescence imaging of OH* and CH* are applied to capture the global flame structure and heat release region. Flame spectroscopy and long bandpass filtered imaging at > 550 nm are performed to evaluate the tendency of soot formation. In general, biodiesels exhibit flame shapes and spray droplet characteristics that are comparable to conventional fuels. In spite of the higher fuel specific consumption, the emission of NOx is found to be lower for biodiesels compared to conventional fuels. The results show that biodiesels can potentially be used as alternative fuels for gas turbine operation
Microwave-induced pyrolysis of waste truck tyres with carbonaceous susceptor for the production of diesel-like fuel
Microwave-induced pyrolysis technique was utilised to pyrolyse waste truck tyres (TT) into useful pyrolysis oil with the aid of activated carbon. The effect of temperature was studied to determine the truck-tyre pyrolysis oil (TTPO) yield, hydrocarbon fractions, chemicals composition, energy yield and fuel properties. The activated carbon functions as microwave absorber to elevate the pyrolysis temperature for enhancing production of pyrolysis oil. The optimal pyrolysis temperature of 500 °C produces highest TTPO yield of 38.12 wt% with calorific value of 42.39 MJkg−1 and energy yield of 40.55 wt%. Detailed analysis shows the TTPO contained large amount of aromatic hydrocarbons and limonene (14.29%) compared to pyrolysis oil from personal car tyre. Among the important chemical compounds also discovered in TTPO are benzene, toluene, xylene (BTX). The relative yields of toluene obtained at 400 °C is 14.85%, whereas the relative yields of benzene and xylene at 450 °C were 0.85 and 7.60%, respectively. The physiochemical properties of TTPO500 are rather similar to conventional diesel, except the slightly lower flash point and calorific value for the former. This work shows that microwave-induced pyrolysis is a promising technique to recover diesel-like fuel for use as supplemental alternative fuel
Optimization studies of microwave-induced co-pyrolysis of empty fruit bunches/waste truck tire using response surface methodology
The central composite design of RSM was utilised for the optimization of experimental conditions of microwave-assisted co-pyrolysis of empty fruit bunch (EFB) and waste truck-tire (TT) to maximise the co-pyrolysis oil and energy yield. The predicted maximum co-pyrolysis oil of 40.0 wt% and energy yield of 59.0% were obtained at the optimum conditions of 505 °C pyrolysis temperature, 65.0% of EFB ratio and 60.0 g of activated carbon loading. The reaction temperature and TT ratio in EFB feedstock were identified as the most significant variables that affect the oil and energy yield. A design of experiment was performed to determine the quality of liquid oil. The result indicates the co-pyrolysis oil (PO65) properties were significantly improved after adding TT to EFB biomass. Olefin-rich pyrolytic oil (39.0%) with high selectivity of D-limonene was produced (28.6%). While, the oxygenates and polyaromatics hydrocarbon were reduced to 9.9% and 7.4%, respectively. The energy recovery analysis shows that the optimised co-pyrolysis oil (PO65) was 20.0% higher as compared to the TT alone. In view of the improved yield and quality of co-pyrolysis oil (PO65), this work shows that co-pyrolysis of EFB/TT presents a viable method to produce diesel-like fuel using the microwave-assisted heating method
Ultra-low emission combustion of diesel-coconut biodiesel fuels by a Mixture Temperature-Controlled Combustion mode
H2-rich syngas strategy to reduce NOx and CO emissions and improve stability limits under premixed swirl combustion mode
The combustion performance of H2-rich model syngas was investigated by using a premixed swirl flame combustor. Syngas consisting mainly of H2 and CO was blended with components such as CH4 and CO2 in a mixing chamber prior to combustion at atmospheric condition. The global flame appearance and emissions performance were examined for high (H2/CO = 3) and moderate (H2/CO = 1.2) H2-rich syngases. Results showed that higher H2 fractions in the syngases produce lower NOx emissions per kWh basis across all equivalence ratios tested. CO emissions are equivalence ratio dependent and are less affected by the H2 fraction in the syngas. Increasing CO2 diluent ratios result in the decrease of NOx, particularly for moderate H2-rich syngases. In contrast, syngas without CO shows an increase of NOx with increasing CO2 for fuel-lean mixtures. Addition of CO2 increases the lean blowout limit of all syngases. Higher fraction of H2 produces lower lean blowout limits due to the characteristics of high diffusivity of hydrogen molecules and high flame speed that assist in the stabilisation of the flame under flame-lean conditions. The range of blowout limits for moderate and high H2-rich and pure hydrogen syngases under diluent ratios up to 25% were within the range of ϕ = 0.12–0.15
Effect of microwave susceptor design on the heating profile of co-pyrolysis between empty fruit bunches and waste truck tire
The effect of microwave susceptor design on the heating profiles of co-pyrolysis between waste truck tyre and empty fruit bunch was studied. Carbonaceous susceptor was used to elevate the pyrolysis temperature along with increased heating rate. Different design of microwave susceptor and its effect towards the heating profiles of the studied co-pyrolysis process was examined. The aim is to determine the effect of heating rates on the pyrolytic-oil yield, calorific value and energy recovery. From the study, it was revealed that the microwave susceptor design (D1) with a horizontal-layer single-bed, located at the bottom (SB-HL-B) of the feedstocks, showed higher heating rate (83 oC min-1). Higher heating rates were observed to significantly increase pyrolytic-oil (39.0 wt%) and energy yield (59.0%). Such heating rate also upgraded the pyrolytic-oil properties, producing oil with higher calorific value (42.20 MJkg-1). Thus, the present study demonstrated a viable method to optimise pyrolytic-oil yield in producing diesel-like fuel through the adoption of a microwave-assisted heating method
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