This paper deals with phase lag (or time-lagged) heat conduction models: the Cattaneo-Vernotte (or thermal wave) model and the dual phase lag model. The main aim is to show that modal analysis of these second order partial differential equations provides a valid and effective approach for analysing and comparing the models. It is known that reliable values for the phase lags of the heat flux and the temperature gradient are not readily available. The modal solutions are used to determine a range of realistic values for these lag times. Furthermore, it is shown that using partial sums of the series solutions for calculating approximate solutions is an efficient procedure. These approximate solutions converge in terms of a so-called energy norm which is stronger than the maximum norm. A model problem where a single heat pulse is applied to a specimen, is used for comparing these models with the Fourier (or parabolic) heat conduction model.

本文涉及相滞（或时滞）热传导模型：Cattaneo-Vernotte（或热波）模型和双相滞后模型。主要目的是表明对这些二阶偏微分方程的模态分析提供了一种有效和有效的方法来分析和比较模型。众所周知，热通量和温度梯度的相位滞后的可靠值不容易获得。模态解用于确定这些滞后时间的实际值范围。此外，表明使用级数解的部分和来计算近似解是一种有效的过程。这些近似解根据所谓的能量范数收敛，该能量范数比最大范数强。