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 coolin...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.展开更多
The mechanism of broadening of slab in continuous casting was studied by numerical simulations and experimental measurements in factories. The mechanism is derived by gradual exclusion of various factors related to th...The mechanism of broadening of slab in continuous casting was studied by numerical simulations and experimental measurements in factories. The mechanism is derived by gradual exclusion of various factors related to the broadening of slab. It is concluded that the slab exposes to no constraint at the direction of narrow face. Because of the static pressure of molten steel, the slab deforms creepily in the direction that consequently results in the broadening of slab. The broadening of slab increases with casting speed and static pressure of molten steel. The decrease of secondary cooling intensity and strength of steel at high temperature also contribute to the broadening of slab. The micro-alloying plays an important role in improving the strength of steel and in reducing the broadening of slab.展开更多
基金supported by the National Key Basic Research and Devel-opment Program of China("973"Project)(Grant No.2012CB720405)the National Natural Science Foundation of China(Grant Nos.51176203 and 51206184)the Natural Science Foundation of Hubei Province(Grant No.2012FFB06905)
文摘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.
基金supported by the Key Projects in the National Science & Technology Pillar Program during the Eleventh Five-Year Plan of China(Grant No. 2006BAE03A04)
文摘The mechanism of broadening of slab in continuous casting was studied by numerical simulations and experimental measurements in factories. The mechanism is derived by gradual exclusion of various factors related to the broadening of slab. It is concluded that the slab exposes to no constraint at the direction of narrow face. Because of the static pressure of molten steel, the slab deforms creepily in the direction that consequently results in the broadening of slab. The broadening of slab increases with casting speed and static pressure of molten steel. The decrease of secondary cooling intensity and strength of steel at high temperature also contribute to the broadening of slab. The micro-alloying plays an important role in improving the strength of steel and in reducing the broadening of slab.
