Bilateral passive thermal management for dynamical temperature regulation

Abstract

Space heating and cooling of buildings account for ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim $$\\end{document} 30% of energy consumed globally. As a result, efforts to reduce the carbon footprint associated with building temperature regulation are crucial to achieving sustainability goals. Passive radiative cooling and sun heating are two promising innovations that can help reduce the energy consumption associated with building temperature regulation. However, these methods are constrained by factors such as climate zones and seasonal changes. In this work, we demonstrate numerically that bilateral photonic metamaterials enabled by vanadium dioxide (VO2) nanoparticles embedded into polyethylene nanogratings can achieve dynamically modulate solar absorptance at one side in winter and achieve radiative cooling on another side. In cold weather, the solar absorptance of this metastructure can change from 0.93 to 0.2 at a critical temperature when VO2 changes from a metallic to an insulating state. This metastructure consists of broadband transparent polyethylene (PE) gratings on the reflective silver (Ag) gratings with the same period and filling ratio. These gratings are deposited on top of the Polydimethylsiloxane (PDMS) thin film. The VO2 nanoparticles enable dynamic solar absorptance modulation for winter space heating, while the PDMS with strong infrared emittance derived from molecular vibrations over the atmospheric window for summer radiative cooling. Temperature response simulations validate that this bilateral design achieves 6 °C subambient temperature drop at noontime in the summer and stabilizes its temperature around 22 °C during the daytime in the winter. This passive dynamical thermal regulation technique can be deployed for energy-saving targets of buildings, vehicles, and greenhouses in areas with large temperature fluctuations.