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热是介质分子无规运动的能量。按爱因斯坦的质能关系式可求得热能所当量的质量,称为热质。从参量热流密度中可导出热质速度,建立了声子气(热质气)的状态方程后可求得热质运动的驱动力。鉴于热量在介质中传递本质上是热质在介质中的运动,所以基于热质守恒与热质动量守恒的热质运动方程,能普适地描述热量传递过程,因此它就是普适导热定律。当热流密度不是很大时,普适导热定律退化为傅里叶导热定律;当瞬态热流很大但忽略空间惯性力时,普适导热定律退化为CV(Cattaneo-Vernotte,CV)模型;而当稳态热流密度很大时,普适导热定律退化为有空间惯性力项的稳态导热定律,它表明稳态导热情况下也会出现非傅里叶导热。
Heat is the energy of a random movement of a medium molecule. According to Einstein’s mass-energy relationship can be obtained by the equivalent mass of thermal energy, known as the thermal quality. The thermal mass velocity can be deduced from the parameter heat flux density, and the driving force of the thermal mass motion can be obtained after the equation of state of phonon gas (hot mass gas) is established. Since the heat transfer in the medium is essentially the movement of the heat medium in the medium, the heat transfer equation based on the conservation of the heat mass and the mass momentum of the heat mass can be universally described. Therefore, it is the universal law of heat conduction. When the heat flux is not very large, the law of generalized heat conduction degenerates into the Fourier heat conduction law. When the transient heat flux is large but neglecting the space inertial force, the generalized heat conduction law degenerates into the CV (Cattaneo-Vernotte, CV) model; When steady-state heat flux is large, the law of generalized heat conduction degenerates into a steady-state heat conduction law with a space inertial force term, which indicates that non-Fourier thermal conduction also occurs under steady state heat conduction.