Study on the effects of electrostatic force and spray characteristics in spray cooling of vertical hot strip

• Published in: Journal of electrostatics Vol. 108; p. 103517
• Main Authors: Lim, Kyung-Hwan, Kang, Jungshin, Yi, Kyung-Woo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2020
• Subjects: Electrostatic force; Heat transfer; Spray characteristics; Spray cooling; Spray cooling; Heat transfer; Spray characteristics; Electrostatic force
• ISSN: 0304-3886; 1873-5738
• DOI: 10.1016/j.elstat.2020.103517

Spray cooling is used in various fields and is particularly important in the metal industry because cooling has a significant effect on the quality of the products. In this study, experiments were conducted to investigate the effects of spray characteristics and electrostatic forces on spray cooling. A heated strip was cooled by spraying through a twin fluid atomizer with different air to liquid mass flow ratios (ALRs) between electrodes that applied a high voltage up to −15 kV. Two-dimensional spray characteristics such as the flux, size, and velocity of the droplets before impacting the strip were measured using phase Doppler anemometry, the cooling process was measured using a thermal imager. Based on these experiments, it was found that there were significantly different cooling behaviors according to the ALR. It was also found that among the different spray characteristics, the axial velocity is the most relevant to the cooling process. In addition, when electrostatic force was applied, through a comparison of the spray characteristics, it was confirmed that the spraying area increased, and the size of the droplets decreased and uniformized. However, the velocity was not significantly affected. As a result, it was verified that the heat transfer was enhanced by the electrostatic force. •Experiments of spray cooling were conducted while varying air to liquid mass flow ratio and electrostatic force.•The cooling pattern varies depending on the ALR and is related to the axial velocity among the spray characteristics.•When electrostatic force is applied, the spraying area increases, the size of droplets decreases and it becomes uniform.•It was confirmed that the heat transfer was enhanced by the effect of electrostatic force.