Assessment of liquid and gas impingement cooling fluids with numerical solution for better steel austempering

Abstract

Abstract Impingement jet heat transfer was studied using liquid and gas fluids to determine better cooling fluid. The materials used were rectangular steel plates of 230 mm by 120 mm by 12 mm, single jet diameters of 10–40 mm with impingement gaps of 115–155 mm. A computational fluid dynamics software application ANSYS 2020R1 was employed for simulation, and lumped thermal mass analysis was used for experimental modeling. The experimental results showed an increase in heat transfer coefficient with increased pipe diameters and with a corresponding increase in impingement gaps and flow rate. This revealed 265.4–383.9 W/m2 K and 85.3–109 W/m2 K at diameter 10 mm and 336.5–365 W/m2 K and 109.0–137.5 W/m2 K at diameter 40 mm for both water and air, respectively. Numerical simulation revealed heat flux of 22518–38.94 W/m2 and 7570.2–4.25 W/m2 and 6742.8–27.1 W/m2 and 4155.6–6.1 W/m at diameters 10 mm and 40 mm, respectively. This confirmed that water remains a better cooling fluid with a 6.2% difference at the diameter of 10 mm and a 0.1% difference at the diameter of 40 mm. An acceptable error margin of 4 to 18% upon the comparison of empirical analysis with numerical simulation is obtained. The above suggests a better cooling rate for the microstructure of the steel using water against air.

Keywords

• Single jet impingement
• Lumped thermal mass
• Liquid and gas
• Numerical simulation
• Impingement cooling fluid