NOx emission reduction reaction of Ammonia-hydrogen with self-sustained pulsating oscillations

Abstract

Unlike hydrocarbon fuel, ammonia (NH3) is an alternative but promising carbon-free renewable fuel. The utilization of NH3 as energy resource can effectively reduce greenhouse gas CO2 emission. Here we explore interdisciplinary physics of ammonia-hydrogen-fueled combustion-sustained pulsating oscillations and its impact on NOx emission via numerical simulations. A longitudinal combustor with both ends acoustically open is developed. The premixed flame and constant-temperature heat exchangers are implemented upstream and downstream. With the model validated, it is applied to gain insights on the effects of 1) the mass flow rate of the fuel mixture, 2) the hydrogen mass fraction relative to the fuel mixture, and 3) the temperature TH of the heat exchangers. It is found that nonlinear pulsating oscillations could be generated, depending on Furthermore, the oscillation amplitude and frequency are shown to strongly depend on and . In addition, as is reduced from 45% to 15%, intermittent oscillations with a period of 100 s are observed to superimpose on the acoustic resonance nature of the combustor with a time scale of 10−2 s. Finally, varying temperatures of the heat exchanger are found to affect NOx generation and decrease the amplitude of the pulsating oscillations somehow.