静电场作用下电介质系统的平衡态及其稳定性

发布时间：2019-07-09 08:56

【摘要】：热力学的本质研究内容是系统内部、系统之间、系统与外界的能量的相互作用;无论是传热还是做功,本质都是能量之间的传递和转移;自然界中能量转移的普遍性和统一性,是热力学的研究的普遍性的基础。热力学是通过定义系统的相应状态参量和状态函数来描述系统的能量变化,所以状态的表达、尤其是平衡状态的表达,是经典热力学中的重中之重。热力学平衡态是系统能量最低的状态,在没有外界作用的条件下任何非平衡态最终都会趋向于平衡态,热力学系统只有在平衡态时才能用统一的状态参量来描述。电磁场能够有效地强化传热传质过程,对电介质系统的平衡及其稳定性有明显地作用。利用热力学定律将电场能量引入热力学基本微分式,构建了电场作用下电介质系统的熵函数,利用平衡态及其稳定性的熵判据导出了静电场作用下电介质系统的平衡条件及稳定条件。相比没有电场作用,平衡条件要求系统各相的等效压强、等效化学势和平行极板间电场强度相等;稳定条件要求产生电场的电荷量与电势成正比。电场作用下的等效压强包括了电场极化作用的力学效果,力学平衡由压强和电极化力共同决定;等效化学势包括了电场极化势能的效果,相平衡由浓度和电势能共同决定。利用相应的等效热力学相关参量和状态方程,就可以将电场作用下的电介质系统的热力学性质准确的描述出来,将电场对系统的作用方式和影响与经典的热力学系统变化统一起来。本文得出的所有热力学结论都有实验文献支持,与实际相符。
文内图片：

图片说明：电场作用下水滴在棕榈油中的变形示意图
[Abstract]:The essence of thermodynamics is the interaction between the energy of the system and the outside world, whether it is heat transfer or work, and the universality and unity of energy transfer in nature is the basis of the universality of thermodynamics. Thermodynamics describes the energy change of the system by defining the corresponding state parameters and state functions of the system, so the expression of state, especially the expression of equilibrium state, is the most important thing in classical thermodynamics. Thermodynamic equilibrium state is the state with the lowest energy of the system. Under the condition of no external action, any non-equilibrium state will eventually tend to equilibrium state. Only in the equilibrium state can the thermodynamic system be described by unified state parameters. The electromagnetic field can effectively enhance the heat and mass transfer process and has an obvious effect on the balance and stability of the dielectric system. The entropy function of the dielectric system under the action of electric field is constructed by introducing the electric field energy into the basic differential equation of thermodynamics by using the law of thermodynamics. The equilibrium condition and stability condition of the dielectric system under the action of electrostatic field are derived by using the entropy criterion of equilibrium state and its stability. Compared with the absence of electric field, the equilibrium condition requires the equivalent pressure of each phase of the system, and the equivalent chemical potential is equal to the electric field intensity between parallel electrodes, and the stable condition requires that the amount of electric field generated is proportional to the electric potential. The equivalent pressure under the action of electric field includes the mechanical effect of electric field polarization, the mechanical balance is determined by the pressure and polarization force, the equivalent chemical potential includes the effect of electric field polarization potential energy, and the phase equilibrium is determined by both concentration and potential energy. By using the corresponding equivalent thermodynamic parameters and equations of state, the thermodynamic properties of the dielectric system under the action of the electric field can be accurately described, and the mode and influence of the electric field on the system can be unified with the changes of the classical thermodynamic system. All the thermodynamic conclusions obtained in this paper are supported by the experimental literature and are in good agreement with the actual situation.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O642

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