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• A biocrude was collected from the hydrothermal liquefaction of algae slurry. • LBV of microalgae oil/RP-3/air mixtures were obtained in a constant volume chamber. • The effects of temperature, pressure, microalgae oil addition on LBV were analyzed. • By fitting experimental data, an empirical formula of LBV with factors was obtained. In the present work, algae-derived biocrude was collected from the hydrothermal liquefaction of algae slurry, and the mixtures of algae-derived biocrude and RP-3 aviation kerosene was used as aviation substitute fuel named as microalgae oil/RP-3 blend. In order to understand the laminar burning velocity (LBV) of microalgae oil/RP-3, experiments have been carried out in a constant volume chamber (CVC) to investigate the effects of initial temperature, initial pressure and microalgae oil addition on the LBV of microalgae oil/RP-3 blend over a wide equivalence ratio range from 0.8 to 1.4. Experimental result shows that with the increase of initial temperature and microalgae oil addition, the LBV of microalgae oil/RP-3 mixture increases, while with the increase of initial pressure the LBV of microalgae oil/RP-3 mixture decreases. According to the method of Metghachi, the relationship between the LBV and its influence factors was obtained, the exponents of α T (ϕ) , β P (ϕ) and γ R (ϕ) indicate that the change of initial temperature and pressure have less effect on LBV around equivalence ratio of 1.1 compared with other equivalence ratio conditions, while the change of microalgae oil addition has more significant effect to improve LBV at equivalence ratio of 1.1. [ABSTRACT FROM AUTHOR]

• We focus on laminar flame characteristics of BFG with various CH 4 additions. • CH 4 addition exhibits opposite effects on S L and L b at ϕ = 0.8–1.2 and ϕ = 1.4. • Thermal effect plays a major role at ϕ = 0.8–1.2 instead of chemical effect at ϕ = 1.4. • R38 and R52 are the main chain branching and chain termination reactions. • OH and H concentrations evidently increase with methane addition. As a typical low heating value fuel, blast furnace gas (BFG) is used as an alternative fuel for gas turbine combustion. Due to its high concentration of inert gas components, natural gas is usually added to improve ignition and stable combustion in the combustion chamber. In this paper, laminar flame characteristics of BFG/CH 4 /air mixtures were investigated using constant volume combustion chamber and CHEMKIN package using the Gri-Mech 3.0 model. Experiments and numerical simulations were conducted at an elevated pressure and temperature of 0.2 MPa and 453 K, equivalence ratios of 0.8–1.4, and mixing ratios of methane of 0, 5, 10, 15%. The results show that the laminar burning velocity decreases rapidly from 24.19 cm/s to 13.90 cm/s at ϕ = 1.4 with the increase of methane addition from 0% to 15%, but obviously increases from 16.49 cm/s to 28.68 cm/s at ϕ = 0.8, from 21.05 cm/s to 35.65 cm/s at ϕ = 1.0, from 23.52 cm/s to 32.09 cm/s at ϕ = 1.2 with the increase of methane addition from 0% to 15%. Meanwhile, methane addition has an opposite effect on the Markstein length at ϕ = 0.8–1.2 and ϕ = 1.4. The thermal, transport and chemical effects were examined, exhibiting a major role of the thermal effect in the range of ϕ = 0.8–1.2 and a significant contribution of the chemical effect at ϕ = 1.4 to the laminar flame propagation of BFG/CH 4 /air mixtures. Further sensitivity analysis shows that R38 (H + O 2 ↔ O + OH) and R52 (H + CH 3 (+M) ↔ CH 4 (+M)) are the main chain branching and chain termination reactions, respectively. Analysis on flame structure indicates that concentrations free radicals, especially OH and H evidently increase with methane addition. The maximum mole fraction of OH increases almost linearly from 1.02 × 10 - 3 to 3.82 × 10 - 3 with the increase of methane addition from 0% to 15%. The maximum mole fraction of H increases with a lower gradient than that of OH from 1.31 × 10 - 3 to 2.89 × 10 - 3 with the increase of methane addition from 0% to 15%. [ABSTRACT FROM AUTHOR]

• We focus on laminar burning velocity of blast furnace gas with very low heat value. • Effects of initial pressure, initial temperature and fuel composition were studied. • Gri-Mech 3.0 mechanism gives the best predications among six kinetic mechanisms. • Chemical kinetic effect is more dominant than thermal and transport effects. • R99 and R45 are the main chain branching and chain termination reactions. Laminar burning velocities of blast furnace gas with low heat value were investigated using constant volume combustion chamber and CHEMKIN package. Experiments and numerical simulations using Li, Davis, Gri-Mech 3.0, San Diego Mech, USC Mech II, NUI Galway Mech models were conducted at initial pressures of 0.1–0.2 MPa, initial temperatures of 303–453 K, and equivalence ratios of 0.8–1.6. Fuel composition was changed considering the volume fraction variation in blast furnace gas with calorific values of 3.27–4.03 MJ/m3. The effects of initial pressure and temperature on laminar burning velocities were correlated with high-order polynomials dependent on the equivalence ratio. The thermal and transport effects were examined and sensitivity analyses were further conducted to study the chemical kinetic effect. The results show that the laminar burning velocities increase with the decrease of initial pressure and the increase of initial temperature, and the Gri-Mech 3.0 mechanism gives very good predications among the six kinetic mechanisms. In addition, the laminar burning velocities increase with the increase of H 2 /CO ratio and the decrease of CO 2 /N 2 ratio under the same low heat value. The chemical kinetic effect plays a major part during the laminar flame propagation under all the operation conditions considered. Due to the high CO content and low H 2 content in blast furnace gas, R99 and R45 are the main chain branching and chain termination reactions, respectively. The effects of initial condition and fuel composition on laminar burning velocities are closely related to the concentrations of H, O and OH radicals. [ABSTRACT FROM AUTHOR]

• This paper focused on the use of LNG in aircraft engine. • Experiments have been done in a constant volume chamber for CH 4 /RP-3/air mixtures at various initial conditions. • Experimental data agree well with previous literature and mechanism of Zeng. • The effects of CH 4 mixing on the laminar burning velocity of CH 4 /RP-3/air premixed have been analyzed. • The effects of CH 4 mixing on the Markstein length of CH 4 /RP-3/air premixed flames have also been analyzed. Experiments have been carried out in a constant volume combustion bomb to investigate the effects of initial temperature (450 and 480 K), initial pressure (0.1 and 0.3 MPa) and CH 4 mixing ratio (0, 0.2, 0.4, 0.6, 0.8, 0.85, 0.9 and 0.95) on the laminar burning velocity and Markstein length of homogeneous, quiescent CH 4 /RP-3/air mixture over wide equivalence ratio from 0.7 to 1.4. Results show that with the increase of initial temperature from 450 to 480 K, no cellular structure in flame is observed, but obvious cellular structure is observed when initial pressure increases to 0.3 MPa at equivalence ratio of 1.2. The laminar burning velocity reaches its maximum in slightly rich mixture (ϕ = 1.1) and with the increase of initial temperature and decrease of initial pressure the peak laminar burning velocity of CH 4 /RP-3/air mixture increases. It is found that the laminar burning velocity of CH 4 /RP-3/air mixture decreases slowly when methane mixing rate increase from 0 to 0.8, but decreases rapidly from 0.8 to 0.95. Analysis results show that at equivalence ratio of 1.1, the Arrhenius factor exp - T a / 2 T ad has greater effect on the laminar burning velocity of CH 4 /RP-3/air mixtures when the methane mixing ratio is larger than 0.8. At equivalence ratio of 0.8 (lean mixture), with the increase of CH 4 mixing ratio the Le - 1 decreases, which leads to the decrease of Markstein length and make the premixed flame tends to be unstable, while at equivalence ratio of 1.4 (rich mixture), with the increase of CH 4 mixing ratio the Ze and δ increase, which stabilizes the premixed flame. [ABSTRACT FROM AUTHOR]