管内盐析两相流动的PDPA试验研究

管内伴有盐析两相流动的研究是了解盐析机理的重要途径。运用相位多普勒粒子分析仪(Phase-Doppler particle analyzer, PDPA)对层流状态下管内Na2SO4溶液的盐析流动规律进行了测量，并详细分析盐析粒子成核速度和溶液流动参数之间的相互关系。试验采用激光单点测量方法对管内充分发展的层流溶液不同截面进行非接触式两相流测量，测量结果表明，随着溶液过饱和度、流动速度及降温速度的变化，管内Na2SO4晶体的盐析速率均会发生不同的变化；盐析粒子的出现对管内层流场产生一定的扰动，扰动引起的湍流脉动提高传热效率从而又加快盐析粒子的形成；所运用的试验手段及分析方法将为研究盐析两相流、掌握动态盐析机理及输送盐溶液装置的优化设计提供一定的参考。

PDPA Experiment Study for Salting-out Two-phase Flow in Rectangular Pipe

The study of the salting-out two-phase flow in the pipe is an important way to understand the salting- out mechanism. The phase- doppler particle analyzer (PDPA) is used to measure the salting-out laminar flow law of sodium sulfate solution in the pipe, while the interrelation between the salting-out particle nucleation rate and solution flow parameters is analyzed. The laser beam measurement method is adopted to carry out noncontact two-phase flow measurement of the different sections of the fully developed laminar flow solution. The measurement results show that with the variation of solution supersaturation, flow velocity and temperature reduction velocity, the salting-out velocity of Na_2SO_4 crystal in pipe will change differently; the emergence of salting-out particles bring a certain disturbance to the laminar flow field, then the arisen turbulent fluctuation improves the heat transfer efficiency and in turn quickens the formation of salting-out particles. The applied experiment method and analysis way will offer some references to the study of salting-out two-phase flow, mastery of dynamic salting-out mechanism and optimal design of salt solution transport equipement.