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Measurements of Liquid Ammonia Sprays Using the ECN Spray M Injector with Injector-To-Injector Comparisons
Li Shen1, Abdullah U Bajwa2, Felix Leach1
1Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, U.K.
Energy & Fuels : an American Chemical Society Journal
|July 28, 2026
Summary
Liquid ammonia injection shows promise for carbon-free engines. This study details liquid ammonia spray behavior, identifying three distinct regimes and offering crucial data for injector design and computational modeling.
Area of Science:
- * Combustion science and alternative fuels.
- * Internal combustion engines and energy systems.
Background:
- * Liquid ammonia is a promising carbon-free fuel for internal combustion engines, especially in maritime applications.
- * Liquid-phase injection offers advantages over gaseous injection but presents challenges like evaporation and flash boiling.
- * Understanding liquid ammonia spray dynamics is critical for efficient fuel delivery and combustion.
Purpose of the Study:
- * To experimentally investigate the spray characteristics of liquid ammonia using two different injectors.
- * To quantify mass flow rates and macroscopic spray parameters under various ambient and injection pressures.
- * To identify the influence of injector design on spray behavior and validate computational models.
Main Methods:
- * High-speed shadowgraph imaging was employed to capture spray morphology and macroscopic parameters (tip penetration, cone angle).
- * Experiments were conducted in a nitrogen-filled constant volume chamber across a pressure range of 1-15 bar.
- * Instantaneous mass flow rate was measured using a pressure-based technique upstream of the injector.
Main Results:
- * Ammonia spray behavior is strongly dependent on the saturation-to-ambient pressure ratio (rp), exhibiting drag-dominated, evaporation-dominated, and flare flash boiling regimes.
- * The ECN Spray M injector showed earlier spray collapse at lower rp due to in-nozzle cavitation, linked to its geometry.
- * Mass flow rate and injected mass from the ECN Spray M injector were largely insensitive to ambient pressure.
Conclusions:
- * Injector geometry significantly impacts liquid ammonia spray morphology and collapse characteristics.
- * The ECN Spray M injector's performance under flashing conditions provides valuable data for fuel injection system design.
- * This study offers a benchmark dataset for validating computational fluid dynamics models of liquid ammonia injection.
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