Determination of the Local Quench Curve for Spray-Cooled Metallic Surfaces

An experimental study of heat transfer from hot metallic surfaces to water sprays was conducted in the single-phase, nucleate boiling, and transition boiling regimes of the quench curve for surface temperatures below 400 ~ C. Heat transfer measurements were made locally in the spray field using a heater surface area of 0.5 cm 2. The hydrodynamic properties of the sprays such as drop diameters, drop velocities, and volumetric spray flux were also measured independently at a position in the spray field identical to that of the heater. The test conditions included variations in volumetric spray flux, mass mean drop diameter, and mean drop velocity of 0.6 x 10 -3 to 9.96 • 10 -3 m3s-~/m 2, 0.434 to 2.005 mm, and 10.6 to 26.5 m/s , respectively. Correlations are presented for water temperatures from 23 to 80 ~ C. These correlations constitute a universal approach to the development of quench curves for industrial sprays commonly employed in materials processing. N O M E N C L A T U R E CHF = C = cp= d = h =