Laminar Burning Velocities of Hydrogen-Blended Methane–Air and Natural Gas–Air Mixtures, Calculated from the Early Stage of p(t) Records in a Spherical Vessel

Abstract

The flammable hydrogen-blended methane–air and natural gas–air mixtures raise specific safety and environmental issues in the industry and transportation; therefore, their explosion characteristics such as the explosion limits, explosion pressures, and rates of pressure rise have significant importance from a safety point of view. At the same time, the laminar burning velocities are the most useful parameters for practical applications and in basic studies for the validation of reaction mechanisms and modeling turbulent combustion. In the present study, an experimental and numerical study of the effect of hydrogen addition on the laminar burning velocity (LBV) of methane–air and natural gas–air mixtures was conducted, using mixtures with equivalence ratios within 0.90 and 1.30 and various hydrogen fractions rH within 0.0 and 0.5. The experiments were performed in a 14 L spherical vessel with central ignition at ambient initial conditions. The LBVs were calculated from p(t) data, determined in accordance with EN 15967, by using only the early stage of flame propagation. The results show that hydrogen addition determines an increase in LBV for all examined binary flammable mixtures. The LBV variation versus the fraction of added hydrogen, rH, follows a linear trend only at moderate hydrogen fractions. The further increase in rH results in a stronger variation in LBV, as shown by both experimental and computed LBVs. Hydrogen addition significantly changes the thermal diffusivity of flammable CH4–air or NG–air mixtures, the rate of heat release, and the concentration of active radical species in the flame front and contribute, thus, to LBV variation.

Experimental Study of the Influence of H2/CO on the CH4 Explosion Pressure and Thermal Behaviors

“…In the current experiment, using this model to calculate the CH 4 –air system, the laminar burning velocity of the 9.5% methane–air mixtures is 0.3964 m/s, which is similar to Mitu’s calculation of 0.40 m/s. 32 …”

“…In the current experiment, using this model to calculate the CH 4 −air system, the laminar burning velocity of the 9.5% methane−air mixtures is 0.3964 m/s, which is similar to Mitu's calculation of 0.40 m/s. 32 Figure 7 shows the laminar burning velocity distribution of the 7% CH 4 −H 2 /CO−air mixed system calculated based on Dahoe's model. The addition of H 2 /CO components changes the laminar burning velocity of the system to different extents and changes the reaction process.…”

Numerical and Experimental Study on Flame Dynamics of the Premixed Methane–Air Mixture at Different Ignition Positions in a Two-Side 45° Branch Tube

“…Xiao et al experimentally investigated the kinetic properties of the hydrogen–air premixed gas at different ignition positions in a confined space and found that the ignition position had an important effect on the combustion characteristics and performance of the flame. Many studies , have shown that fuel composition and hydrogen fraction significantly affect the flame velocity and pressure, and an increase in the hydrogen fraction leads to an increase in the laminar burning velocity. Mitu et al , studied the effects of various initial pressures and compositions on the laminar burning velocity of methane–air–inert mixtures in a centrally ignited spherical vessel.…”

Investigation of the Suppression of Methane Explosions by N2/CO2 Mixtures in Different Proportions

“…Methane is an excellent alternative energy source for petroleum and an alternative fuel used in industry. , It plays an important role in the development of energy worldwide. As a high-quality fuel and chemical raw material, methane has a high combustion efficiency . This provides energy for industrial manufacturing, and methane can also be used in organic curing reactions with hydrogen (H 2 ) to realize hydrogen storage and transport under easily accessible temperatures and pressures. − However, methane is highly combustible such that the methane–oxygen mixture is readily ignited .…”