RESS法制备微细颗粒的喷嘴流动模型

Flow model of a nozzle for superfine particles by using rapid expansion of a supercritical solution

通过对超临界流体快速膨胀法(rapid expansion of supercritical solution,RESS)流动过程的简化与分析,建立了喷嘴节流流动过程模型,一维定常过程数学模型的描述包括了锥体入口段、直管膨胀段和到达马赫盘位置的出口超音速膨胀段.给出了模型中的主要计算参数来源以及解算过程的基本思路.据此模型,在给定初值条件下,对各个阶段的流动状态进行模拟计算,得到了流体的密度、压力、温度、速度等参数沿喷嘴轴向的变化数据,并进行了初步验证.该模型和模拟过程能够为实现制备均一微细颗粒的实际操作条件和优化过程参数奠定基础.

According to the predigestion and analysis of the rapid expansion of a supercritical solution process, a flow model of a nozzle for superfine particles preparation is established. The description of the one-dimensional time-independent flow model includes a conical entrance segment, straight pipe and outlet segment for ultrasonic expansion till mach disk. The main parameters origin in the model and the basic mechanisms of calculating the solution are also presented. Based on the model of the RESS process, the simulation of flow state in each stage is realized and some data of parameters including temperature, pressure, density and velocity along the axis of the nozzle are presented. Some guidelines to optimize parameters are offered to achieve uniform superfine particles.