Ignition delay time and laminar flame speed measurements of ammonia blended with dimethyl ether: A promising low carbon fuel blend

By Gani Issayev, B. Giri, A. Elbaz, K. Shrestha, F. Mauss, W. Roberts, A. Farooq. Renewable Energy, 2022

223 citations recorded by the source corpus.

Abstract Ammonia (NH3) has recently received much attention as a promising future fuel for mobility and power generation. The use of ammonia as a fueling vector can help curb global warming by cutting CO2 emissions because it is a carbon-free fuel and a hydrogen carrier with a high percentage of hydrogen atoms per unit volume. Liquid ammonia contains a higher volumetric density of hydrogen than liquid hydrogen. The low reactivity of ammonia, however, hinders its direct usage as a combustible fuel. One feasible way to boost the reactivity of ammonia is to target a dual-fuel system comprising of ammonia and a suitable combustion promoter. In this work, combustion properties of ammonia were investigated by blending it with various proportions of dimethyl ether (DME) using a rapid compression machine (RCM) and a constant volume spherical reactor (CVSR) over a wide range of experimental conditions. DME is a highly reactive fuel that may be produced in a sustainable carbon cycle with a net zero-carbon emission. Ignition delay times (IDTs) of NH3/DME blends were measured over a temperature (T) range of 649–950 K, pressures (P) of 20 and 40 bar, equivalence ratios (Φ) of 0.5 and 1 for a range of DME mole fractions (χDME) of 0.05–0.5 in the blends. In addition, the laminar burning velocities of NH3/DME blends were measured at P = 1, 3 and 5 bar, Φ = 0.8 to Φ = 1.3 and T = 300 K for χDME ranging 0.18 to 0.47. Our results suggest that DME is a good ignition promoter, resulting in a significant shortening of IDTs and an increase of flame speeds of NH3. A detailed chemical model has been developed and validated against the experimental data. Overall, our kinetic model offered reasonable predictive capabilities capturing the experimental trends over a wide range of conditions. In the worst-case scenario, our model underpredicted IDTs by a factor of ∼2.5 while overpredicting laminar flame speed by ∼20%.

Subfields: Atmospheric Science, Fluid Flow and Transfer Processes, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/45e6a0027e32f0d94a7f21045850d48fbbc9beaf