Experimental study on the combustion of NH3/H2/air based on the passive turbulent jet ignition

Abstract

The mixture of ammonia (NH3) and hydrogen (H2) is the potential alternative fuel for internal combustion engines (ICEs). The turbulent jet ignition (TJI) system can provide high ignition energy and turbulent disturbance to promote the combustion of the mixture for NH3/H2 ICEs. Therefore, the combustion characteristics of NH3/H2/air under passive TJI conditions were experimentally studied in the present study. The experiment was conducted in a constant volume combustion bomb, and the effect of fuel composition and equivalence ratio was investigated. The experimental results show that compared to spark ignition, the combustion of NH3/H2 can be effectively improved by using TJI, especially under high NH3 fraction conditions. The addition of H2 has a significant positive effect on the ignition and combustion performance. With the addition of H2, the ignition delay and combustion duration decrease evidently. And the H2 addition is beneficial for improving the ignition mechanism and achieving flame ignition. In addition, poor ignition performance may occur under rich conditions due to the fluid-dynamic quenching of the jet. However, the high flame propagation rate on the rich side still leads to lower combustion duration. Moreover, increasing the orifices number appropriately can enhance the ignition and combustion performance. The jet strength is weakened by the increased total orifice area and the ignition of NH3/H2 can be improved.