Negative thermal transport and giant thermal rectification unveiled in a periodic-oscillating temperature system

Thermal diodes, based on the thermal rectification effect, have demonstrated great promise for advanced thermal management. In previous studies, almost all thermal diodes were discussed under the condition of steady states, while the heat source of a practical thermal system is often operated under dynamically fluctuating temperatures. Therefore, in this work, we employ the finite element simulation to investigate the transient thermal rectification in a heterojunction model that exhibits strong steady-state thermal rectification. A unidirectional energy transport in the heterojunction system, decoupled from the steady-state temperature bias, is observed under a time-dependent fluctuating heat source. This phenomenon enables the straightforward realization of both giant thermal rectification and negative thermal transport. Furthermore, a series of novel thermal regulation strategies are unveiled by adjusting the average temperature, frequency, phase of the heat source. Our work not only deepens the fundamental understanding of thermal regulation in time-dependent oscillating temperature systems, but also uncovers many unexplored energy-saving thermal management strategies.