Laminar Burning Velocity Measurement of CH₄/NH₃/H₂–Air Premixed Flames under Engine Relevant Conditions

Abstract

Accessibility of affordable clean energy is important for accomplishing economic development and advancement alongside progress in environmental change. In this pursuit, the present study proposes an alternate ternary fuel blend with better fundamental combustion characteristics than natural gas/methane. This work focuses on the laminar burning velocity measurement of a CH4/10% NH3/H2 ternary blend under elevated pressure and temperature conditions using the externally heated diverging channel technique. The NH3 volume fraction is maintained at 10% by volume in a H2:CH4 (1:4) fuel blend and is comparable to a CH4 + air mixture in terms of mixture burning velocity and flame temperature with ∼25% lower carbon emissions. The experimental measurements are obtained for elevated temperatures (300–750 K), pressures (0.1–0.5 MPa), and ϕ = 0.7–1.4 equivalence ratio range. The measured mixture burning velocities of CH4/NH3/H2 mixtures are nearly similar to CH4 + air mixtures at elevated pressures. The pressure and temperature exponents are derived to establish their codependency. Therefore, a revised power-law correlation is proposed for burning velocity variation at high pressures and temperatures. Predictions of Li and Okafor kinetic models coincide well with the present experimental measurements up to 0.5 MPa, whereas Shrestha and improved GRI 3.0 mechanisms overpredict the velocity values. The reduction in HCO to H conversion reduces the burning velocity with pressure increment. The present work competently compares the combustion characteristics of CH4/NH3/H2–air mixtures with CH4 fuel and establishes the proposed ternary blend as a viable solution to attain sustainability goals with reduced carbon emissions.