Experimental Characterization of Superheated Ammonia Spray From a Single-Hole Spray M Injector

Abstract The growing recognition of ammonia as a carbon-free alternative fuel for both transportation and power generation is underscored by numerous studies. While the use of gaseous ammonia injection has been extensively considered, research on the direct injection of liquid ammonia remains relatively scarce, especially in the case of internal combustion engines (ICE). The application of liquid ammonia in gas turbines offers economic and size-related advantages over gaseous ammonia injection. But the liquid ammonia's instantaneous spray flash-boiling and its high latent heat of vaporization induce the necessity of employing preheated swirling air to enhance flame stability, mitigating the strong cooling effect induced. The preference for direct injection of liquid ammonia is driven by its efficacy in controlling in-cylinder air–fuel ratios and optimizing thermal efficiency. This study presents macroscopic and near-field Schlieren measurements of a one-hole Engine Combustion Network (ECN) Spray M, representative of direct liquid injector for engine, with ammonia for different degrees of superheating. Spray angles and penetration length are provided as a function of the superheat degree with also a focus near the injector nozzle. Additionally, in-spray temperature measurements are presented, providing the first valuable information for modeling purposes.