Combustion and Emission Characteristics of Ammonia Jet Flames, Based on a Controllable Activated Thermal Atmosphere 2023-01-1645

Ammonia is a new type of carbon-free fuel with low cost, clean and safe. The research and application of zero-carbon fuel internal combustion engines has become the mainstream of future development. However, there still exist problems should be solved in the application of ammonia fuel. Due to the lower flame laminar speed and higher ignition temperature, ammonia may have unstable combustion phenomena. In this work, the characteristics of ammonia combustion have been investigated, based on controllable thermal activated atmosphere burner. The ignition delay has been used to analyze the ammonia combustion characteristics. With the increase in co-flow temperature, the ignition delay of ammonia/air has an obvious decline. In order to investigate the emission characteristics of ammonia, CHEMKIN is used to validate the different chemical reaction mechanisms and analyse the ammonia emissions. With the increase in environmental temperature, the NOx increases and NO is the main pollutant; With the increase of pressure, N₂O and NO₂ increase, while NO decreases. At 1153K, compared to low pressure, the ignition delay at high temperature and pressure decreases rapidly, from 150 ms to 20 ms. With the increase in environmental pressure, NO continues to decrease, while N₂O and NO have a slight increase. At the temperature of 1553K, if the pressure changes from 1MPa to 5MPa, the N₂O changes from 1ppm to 2ppm. But as soon as the pressure increases in the 5MPa-9MPa range, the amount of increase is only 0.6ppm/4MPa. Above all, the study of the autoignition characteristics and emissions of ammonia turbulent flame is particularly important for the application to the ammonia engine.