Numerical simulation of the hydrodynamics and mass transfer in the capping of large size Z-cut plates

Abstract

Numerical simulation of the hydrodynamics and mass transfer involved in the capping of large size Z-cut KDP plates has been performed. The variations of surface supersaturation with thin layer height, bulk supersaturation and rotation rate are analyzed. The results show that keeping still is very unfavorable for the growth of thin layer, a certain rotation rate should be applied to the Z-cut plate to increase the concentration gradient across the (0 0 1) face, thus making sure that thin layers can grow from the edges while small pyramids barely grow from the face center. Given the result that end faces of thin layers nearly bear a bulk supersaturation, a relative low bulk supersaturation will be better to ensure both the growth of thin layers and the good surface uniformity brought by low supersaturation. Moreover, as thin layers grow, rotation rate should be increased to make up the insufficient solute supply resulting from the decreasing linear speed. The optimal parameters for rapid and high-quality capping of large size Z-cut plates are suggested, the relevant simulation results are also presented.