EXPERIMENTAL STUDY ON LIQUID NITROGEN SPRAY IN ATMOSPHERIC ENVIRONMENT

摘要

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