Generalized constructal optimization for the secondary cooling process of slab continuous casting based on entransy theory

Abstract

Based on constructal theory and entransy theory, a generalized constructal optimization of a solidification heat transfer process of slab continuous casting for a specified total water flow rate in the secondary cooling zone was carried out. A complex function was taken as the optimization objective to perform the casting. The complex function was composed of the functions of the entransy dissipation and surface temperature gradient of the slab. The optimal water distribution at the sections of the secondary cooling zone were obtained. The effects of the total water flow rate in the secondary cooling zone, casting speed, superheat and water distribution on the generalized constructal optimizations of the secondary cooling process were analyzed. The results show that on comparing the optimization results obtained based on the optimal water distributions of the 8 sections in the secondary cooling zone with those based on the initial ones, the complex function and the functions of the entransy dissipation and surface temperature gradient after optimization decreased by 43.25%, 5.90% and 80.60%, respectively. The quality and energy storage of the slab had obviously improved in this case. The complex function, composed of the functions of the entransy dissipation and surface temperature gradient of the slab, was a compromise between the internal and surface temperature gradients of the slab. Essentially, it is also the compromise between energy storage and quality of the slab. The “generalized constructal optimization” based on the minimum complex function can provide an optimal alternative scheme from the point of view of improving energy storage and quality for the parameter design and dynamic operation of the solidification heat transfer process of slab continuous casting.