汽—液相变过程的热力学分析

Thermodynamic Analysis of a Vapor-liquid Phase Transition Process

应用热力学理论对工程上常见的实际汽 -液相变过程进行热力学分析 ,研究实施过程的必要热力学条件、过程进行的规律及影响因素。文中重点研究了沸腾相变过程 ,特别是对相变对流换热系数的提高及其影响因素从热力学角度做出了分析 ,强调在相变过程中两相间的化学势差Δμ是过程的一个重要的广义热力学驱动力 ,换热过程是在Δμ和ΔT共同作用下并结合流体的对流运动来实现的。与单相的对流换热不同的是 ,这里加入了驱动力Δμ的作用 。

By applying a thermodynamic theory, a thermodynamic analysis was conducted of the actual vapor-liquid phase transition process commonly encountered in engineering practice. The necessary thermodynamic conditions for realizing the above-mentioned process are discussed along with the laws governing the progress of the process and relevant influencing factors. The authors have focused on the study of boiling phase-transition process, and especially analyzed from a thermodynamic perspective the enhancement of convection heat-transfer factor due to the phase transition and also the related influencing factors. It is stressed that in a phase-transition process the chemical potential difference Δμ between the two coexisting phases serves as a major generalized thermodynamic driving force of the process. The heat exchange process has been realized under the joint action of Δμ and ΔT and in tandem with the convection movement of fluids. The introduction of the driving force Δμ makes the above process different from a single-phase convection heat exchange and this also constitutes a main cause leading to an intensification of the phase-transition heat exchange process.