Numerical Simulation of the Hydrodynamics and Mass Transfer in the Cuboid KDP Crystal Growth under the Jet-Rotating Crystal Method

A novel method of crystal growth by introducing jet flow to the pyramidal-restriction long-seed growth system of potassium dihydrogen phosphate (KH2PO4, KDP) in rotating crystal method, namely, the jet-rotating crystal method, is proposed. To evaluate the prospect of this new method, three-dimensional (3D) time-dependent numerical simulations of flow and mass transfer involved in the jet-rotating crystal method are conducted. Compared with the rotating crystal method, the jet-rotating crystal method can improve the magnitude and distribution homogeneity of the prismatic face supersaturation and obtain high-quality KDP crystals. The supersaturation on the prismatic face as a function of rotation rate, jet velocity, and crystal size is investigated. The effects of solution flow on mass transfer are analyzed in detail. A further improvement in the magnitude and distribution homogeneity of the prismatic face supersaturation can be observed through designing the jet flow pipes to swing periodically in vertical plane. Besides, the role of natural and forced convection in mass transport is discussed, which indicates that the effects of natural convection can be neglected when the jet velocity is equal to or greater than 0.6 m s(-1).