Flow visualization study of two-phase flashing spray with iso-pentane

The explosive flashing spray commonly occurs during the accidental release of flammable and toxic pressure-liquefied gases in chemical or nuclear industry. This work conducts a small-scale flashing spray experiment in house to simulate the accidental release, aiming to investigate the macroscopic atomization characteristics, which is helpful for the risk assessments and therefore minimizing the impact of the release hazard. The iso-pentane was taken as the working medium, and a transparent straight-tube nozzle with inner diameter of 0.6 mm and length of 40 mm was employed to generate the flashing spray vertically. A high-speed camera was used to record the images of the flashing spray. The whole dynamic evolution was obtained. The effects of injection pressure (0.6 to 2.4 MPa) and initial temperature (40 to 60 ^oC) were fully explored, respectively. The experiment results indicate that the superheat and injection pressure have a coupled effect on flashing spray. The release of superheat results in phase change with the generation of bubble within liquid, which facilitates the break-up of liquid core and ligament liquid. Meanwhile, the increment of injection pressure can enhance the disturbance of the flow and the number of nucleation.