Spray Heat Transfer Analysis of Steel Making Process by Using Particle-Based Numerical Simulation

Spray cooling is often used in the steel manufacturing process, and the steel plate temperature at the time of manufacture affects productivity and quality. Therefore, the spray heat transfer coefficient estimation becomes important when determining manufacturing conditions or when designing manufacturing facilities. The conventional heat transfer coefficient estimation method is obtained by reversely analyzing the temperature of the steel plate when the heated steel plate is cooled by a single nozzle used or an experimental device simulating a real machine manufacturing facility. However, in actual equipment manufacturing facilities, it is difficult to grasp the heat transfer and flow state of heat transfer part details due to the presence of rolls, water staying on steel plates, and spray when a large amount of water is injected, heat transfer by numerical calculation Coefficient prediction has been desired. In order to calculate the actual physical phenomena even with a single spray, one hundred million droplets of about hundred micrometer diameter are calculated while resolving a few micrometers of vapor film thickness at the time of collision of the steel plates with droplets, so calculation load is huge.Therefore, the authors describe the heat transfer coefficient of the experimental results as a function of the collision pressure because the vapor film is broken and the heat transfer is promoted if the collision pressure of the spray droplets to the steel plate is high [1]. The heat transfer coefficient was calculated by substituting the collision pressure obtained by the numerical calculation into the experimental formula. The behavior of the spray cooling water includes a complex free interface, but can be calculated by the MPS method, and there is an example [2] where the flow rate of the spray cooling water between rolls of a real steel facility is calculated. In the present examination, the MPS method was similarly used for the prediction of the spray collision pressure, and the calculated particle diameter was also set to 3 mm as in the case [2]. As a result of examination, the particles were injected from the spray outlet so as to match the actual water density, and the actual droplet size was matched with the actual collision pressure.