Transient heat transfer in packed beds: The significance of the history term

Describing transient heat transfer in heterogeneous media is still a problem. This study was conducted to investigate if the consideration of the history term is a way to improve the description of this phenomenon. To that end the history term is analytically derived for a particle in a packed bed with stagnant fluid and its order of magnitude is estimated. The history term is significant in liquid–solid packed beds, whereas in the case of gas–solid packed beds the history term can usually be neglected except for very large heat fluxes as for instance in laser-pulse heating.