Numerical investigation of the heat transfer characteristics of a water droplet on a high-temperature steel pipe

Spray cooling depends on the collective action of myriad microdroplets impacting a hot surface. By studying the heat transfer mechanisms that occur when droplets come into contact with a surface, it is possible to determine the influence of various factors on the cooling efficiency of these droplets. In this paper, the heat transfer behavior of droplet impact on high-temperature steel pipes was studied by using numerical simulation methods. A hot-rolled seamless steel pipe is used to investigate the effects of droplet diameter (1–10 mm) and impact velocity (0.5–4 m/s) on the heat transfer under high temperature conditions. The results show that various process parameters exhibit the same influence pattern on heat transfer for both the inner and outer walls. The maximum heat transfer coefficient increases with the increase in the droplet impact velocity, but the cooling duration gradually decreases with the increase in the impact cooling velocity. At a fixed impact velocity, increasing the droplet diameter decreases the peak heat transfer coefficient. It is worth noting that under the same process parameters, the heat transfer coefficient of the outer wall surface is greater than that of the inner wall.