对近临界混合流体的活塞效应、Soret效应及相分离现象和其相互作用机理的研究对深入理解近临界混合流体的热质传递现象和机理及其进一步应用都具有重要的意义。本研究将从工程热物理、统计物理及制冷与低温工程等交叉学科的角度出发，结合实验研究、理论分析和数值计算，对小型密闭腔体中的近临界氮氩混合流体的活塞效应进行详细的研究，结合激光干涉可视化测量获得近临界混合流体活塞效应的热物理特征；通过对组分浓度分布的测量获得对近临界混合流体Soret效应的描述，并结合数值计算分析得出活塞效应和Soret效应的相互作用机理；通过激光干涉可视化测量对近临界混合流体的相分离现象和自然对流现象进行实验研究，综合考虑活塞效应和Soret效应的影响对相分离现象和自然对流现象进行理论分析和数值计算。通过本研究可进一步深化对近临界混合流体热质传递现象和机理的认识，为其应用提供基础数据；同时也可促进工程热物理学科同其他学科的交叉

It is very important to investigate the piston effect, Soret effect and decompsition phenomenon and their interaction mechanisms to reach a deep understanding of the heat and mass transport mechanisms of near-critical mixture fluid and to widen its application. From the interdisciplines of the engineering thermophysics, stastical physics and refrigeration and cryogenics, with the aid of the experimental investigation, theoretical and numerical analyses, the laser holographic interferemeter will be used to detect the piston effect of the near-critical N2-Ar mixture fluid in a small-scale experimental cell. By measuring the fluid concentration of the near-critical N2-Ar mixture fluid, the Soret effect can be characterized experimentally and the interaction mechanism between the piston effect and Soret effect can be understood from the numerical analysis; the decomposition phenomenon and natural convection of the near-critical N2-Ar mixture fluid can be experimentally investigated by using the laser holographic interferemeter and theoretically by using numerical analysis. The research results can be very instructive to deepen the understanding of the heat and mass transport phenomena and mechanisms of the near-critical mixture fluid and can provide fundamental data for its further application; furthermore, it can add the new knowledge to the discipline of the engineering thermophysics.