Characteristics of Ammonia Spray Injected by Pressure-Swirl Atomizers

Abstract

Ammonia (NH3) is a potential carbon-free energy carrier for the storage, transportation, and utilization of energy produced from renewable sources. Ammonia can be used as a liquid fuel for spray combustion in industrial furnaces, engines, and gas turbines. Spray characteristics of liquid ammonia injected by commercial pressure-swirl atomizers (Delavan type WDA nozzles) have been investigated and compared with ethanol through shadowgraph images. The injection is driven by vapor pressure in the ammonia cylinder. Since ammonia has a boiling point lower than the room temperature, decompression evaporation of ammonia liquid may occur due to pressure drops both in the fuel supply line and across the spray nozzle. To avoid evaporation before the spray nozzle, tubes upstream were cooled down in the experiment. As a result, ammonia sprays with the hollow cone were formed. Unlike the ethanol spray in which the atomization into droplets were clearly observed, ammonia droplets evaporate while the atomization proceeds. Unique evaporating spray patterns were observed for ammonia. It was also found that the spray cone angle of ammonia is larger than that of ethanol, and then the catalog value of water with the 30ºnozzle. On the other hand, the measured cone angles of them show no great difference with the 80ºnozzle. Flow rate roughly correlates with injection pressure for ammonia, ethanol and water.