热学中的新物理量

NEW PHYSICAL QUANTITIES IN HEAT

通过与力学、电学的比拟,在热学中引入了热量的势、势能、速度、动能等新的物理量,从而可建立热量运动的守恒方程组。热量传递是不可逆过程,耗散的是热量的"能量"。以耗散最小(热阻最小)为目标函数,就能对传热过程进行优化。傅立叶导热定律是热量运动方程在不计动量变化条件下的简化。在极端(低温、超高速、纳米尺度)条件下不再适用,引入新物理量后,能阐明热波、导热系数尺度效应等"超常"物理现象。

Some new concepts, such as potential, potential energy, velocity, kinetic energy of heat, are introduced into heat based on analogy with mechanics and electrics. As a result conservation equations for motion of heat can be established. In the irreversible process of heat transfer, what dissipated is the “energy” of heat. Taking the least dissipation of the energy of heat （thermal resistance） as an objective function, heat transfer can be optimized. Fourier＇s law is the simplified momentum equation of heat when the variation of momentum can be ignored, and it breaks down under extreme conditions （i.e. ultra low temperature, supertransient, nanoscale）. Introducing such new quantities can also explain the abnormal phenomena, e.g., thermal wave and size effect of thermal conductivity.