In spray cooling system, the liquid coolant is broken into numerous fine droplets through a spray nozzle to cool the target. The liquid nitrogen spray could obtain low cooling temperature and excellent heat transfer performance with phase change in a large temperature difference. It can be widely used in low temperature tunnel cooling, ground simulation environment and laser therapy. The open loop liquid nitrogen spray platform is built to investigate the nitrogen spray characteristics. The solid cone vortex nozzle WL32 (3.18 mm diameter) and fine fog nozzle P66 (1.68 mm diameter) are used in the experiment. The spray pressure differences (0.25MPa to 0.8MPa) are sourced by the high pressure room temperature gas nitrogen and controlled through a manual valve. In the experiment, the spray field is recorded by a high speed camera (HG-100K from Redlake Co.) and the diameter of the spray droplet from WL32 is analyzed through the Malvern Spraytec laser particle size analyzer. The pressure difference between nozzle inlet and outlet has different influence on the spray angle of WL32 and P66. The quantity of spray droplets of WL32 increases with the increasing pressure, which leads to the improvement of the atomizing effect and the decline of Sauter Mean Diameter.
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