ID 166

Flow Visualization Study of Two-Phase Flashing Spray with Iso-pentane

 

Abstract:

This work conducts a small-scale flashing spray experiment in house to simulate the accidental release of flammable liquid in chemical or nuclear industry, aiming to investigate the macroscopic atomization characteristics, which is helpful for the risk assessments and therefore minimizing the impact for the release hazard. The volatile and flammable 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 gray-scale images of the flashing spray with a spurt duration of 1s by using back illumination method, and a threshold algorithm was introduced to quantify the spray angle. All the spray angle and width of the whole dynamic evolution were obtained. The effects of injection pressure (0.6 to 2.4 MPa) and temperature (40 to 60 ℃) were fully explored, respectively. The experiment results indicate that the superheat and driving pressure have a coupled effect on flashing spray. Higher superheat results in larger spray angle and radial expansion, whereas superheat has less effect on droplet concentration under lower driving pressure. Higher driving pressure causes higher droplet concentration, but driving pressure has greater effect on spray angle and width at lower injection temperature. Intense atomization of happens the flashing spray only when raising the superheat and driving pressure simultaneously.