Thermal diodes, which allow heat transfer in a preferential direction while being blocked in a reverse direction, have numerous applications in thermal management, information processing, energy harvesting, etc. Typical materials of thermal diodes in previous works include phase-change and magneto-optical materials. However, such thermal diodes depend highly on specific working temperatures or external magnetic fields. In this work, we propose a near-field radiative thermal diode (NFRTD) based on two Weyl semimetal (WSM) nanoparticles (NPs) mediated by a WSM planar substrate, which works without an external magnetic field and with flexible temperatures. Numerical results show that the maximum rectification ratio of NFRTD can be up to 2673 when the emitter is 200 K and receiver is 180 K, which exceeds the maximum value reported in some previous works by more than 10 times. The underlying physical mechanism is the strong coupling of the localized plasmon modes in the NPs and nonreciprocal surface plasmon polaritons in the substrate. In addition, we calculate the distribution of the Green's function and reflection coefficient to investigate nonreciprocal energy transfer in NFRTDs. Finally, we discuss the effects of momentum separation on the rectification performance of the NFRTD. This work demonstrates the great potential of WSMs in thermal rectification and paves a path for designing high-performance NFRTDs.

The epsilon-near-zero characteristics of the near-field radiative heat transfer between two symmetric biaxial α-MoO ₃ slabs are investigated.

With the development of modern technology and economy, environmental protection and sustainable development have become the focus of global attention. The promotion and development of electric vehicles (EVs) have bright prospects. However, many challenges need to be faced seriously. Under different operating conditions, various safety problems of electric vehicles emerge one after another, especially the hidden danger of battery overheating which threatens the performance of electric vehicles. This paper aims to design and optimize a new indirect liquid cooling system for cylindrical lithium-ion batteries. Various design schemes for different cooling channel structures and cooling liquid inlet directions are proposed, and the corresponding solid-fluid coupling model is established. COMSOL Multiphysics simulation software is adopted to simulate and analyze the cooling systems. An approximate model is constructed using the Kriging method, which is considered to optimize the battery cooling system and improve the optimization results. Sensitivity parameter analysis and the optimization design of system structure are performed through a set of influencing factors in the battery thermal management. The results indicate that the method used in this paper can effectively reduce the maximum core temperature and balance the temperature differences of the battery pack. Compared with the original design, the optimized design, which is based on the non-dominated sorting genetic algorithm (NSGA-II), has an excellent ability in the optimized thermal management system to dissipate thermal energy and keep the overall cooling uniformity of the battery and thermal management system. Furthermore, the optimized system can also prevent thermal runaway propagation under thermal abuse conditions. In summary, this research can provide some practical suggestions and ideas for the engineering and production applications and structural optimization design carried by electric vehicles.