Effective medium theory with hybrid impacts of phase symmetry and asymmetry for analyzing phase transition behavior

Maintaining temperature is crucial in both daily life and industrial settings, ensuring human comfort and device functionality. In the quest for energy conservation and emission reduction, several contemporary passive temperature control technologies have emerged, including phase change temperature control, shape memory alloys, solar thermal utilization, sky radiation cooling, and heat pipe systems. However, there is a pressing need for more quantitative methods to further optimize temperature maintenance. With advancements in theoretical thermotics and the emergence of thermal metamaterials, it is clear that temperature fields can be precisely manipulated by fine-tuning thermal and structural parameters. This chapter introduces three innovative devices: the energy-free thermostat, the negative-energy thermostat, and the multi-temperature maintenance container. All are grounded in the principles of thermal metamaterials and primarily operate under conduction heat transfer conditions. When compared with traditional technologies, the unparalleled efficacy of thermal metamaterials in temperature management is evident. Moreover, brief prospects present strategies to improve temperature maintenance under convection heat transfer, thus expanding the application spectrum of thermal metamaterials. This chapter concludes by spotlighting the evolution and interplay of the aforementioned three devices, marking the progression of thermal metamaterials from theoretical ideas to tangible engineering solutions. These insights not only bridge the gap between applied physics and engineering but also underscore the practical potential of thermal metamaterials.

Thermal Metamaterials for Temperature Maintenance: From Advances in Heat Conduction to Future Convection Prospects

Zhou

2024

Fundamental Methods and Design Paradigm for Omnithermotics

Wang,

Xu,

Wang

et al. 2024

This chapter offers a comprehensive exploration into the realm of thermal metamaterials, emphasizing their transformative potential in regulating the three primary modes of heat transfer: conduction, convection, and radiation. The foundation of this exploration is rooted in the theory of transformation omnithermotics, which has been instrumental in unifying these heat transfer modes. The article delves into various functional designs, including omnithermal metamaterials capable of thermal cloaking, concentration, and rotation. The effective medium theory further broadens the scope, allowing for the simultaneous manipulation of the three heat transfer modes. A notable highlight is the introduction of omnithermal restructurable metasurfaces, which exhibit dual properties in both infrared and visible light spectrums. Additionally, this chapter touches upon other artificially designed structures, such as radiative cooling and engineered cellular solids, drawing parallels with natural counterparts like wood and bone. The BCC lattice structure, in particular, is spotlighted for its unique thermal and mechanical properties, making it a promising candidate for future applications. The culmination of these findings underscores the vast potential of thermal metamaterials in diverse applications, from energy efficiency to aerospace engineering.

Geometric Phases in Particle Diffusion with Non-Hermitian Hamiltonian Structures

Yang,

Huang

2024

Geometric phases in particle diffusion systems offer a different understanding beyond traditional Brownian motion and Fick’s laws. Here we introduce a unique structure composed of two rings moving in opposite directions and a stationary intermediate layer, which plays multifunctional roles in controlling particle diffusion. Numerical simulations using COMSOL Multiphysics validate the theoretical framework and provide deeper insights into the behavior of geometric phase. We also describe a bilayer particle-diffusion cloak, illustrating its simple design and adaptable control mechanisms. This system has potential applications in industries like healthcare and environmental management, thus expanding the understanding of the geometric phase and offering insights for the design of particle-diffusion metamaterials.