Numerical Study of Transient Ammonia Flow and Condensation in an Intake System Pipe

Ammonia is considered a zero-carbon clean fuel; however, In addition to its combustion performance, due to its toxicity, corrosiveness, and easy to liquefy during in-pipe delivery, the safety of the ammonia intake system is a significant concern. This paper presents a simulation and analytical model of the ammonia fuel intake manifold and main pipe flow field, considering phase change model. Verification of the accuracy of the phase change model through steady-state calculations. Transient calculations are conducted to analyze the flow field characteristics within the intake system pipe, as well as the effects of manifold valve operation (opening and closing), wall temperatures, and inlet velocities on the phase change within the pipe. An analysis of the flow field characteristics in the intake system reveals that a flow separation occurs downstream of the junction between the manifold and the main pipe. The heat transfer increases in a short time due to the low velocity, which leads to condensation. The impact of valve opening and closing on condensation is also investigated, and it was found that the peak condensation volume occurs after the valve is closed. Furthermore, the condensation volume shows similar trends under varying wall temperatures and inlet velocities, with wall temperature playing a decisive role in determining the condensation amount.