This paper introduces a new type of gypsum-based humidity-control material. The material combines gypsum–silica gel humidity-control material with 20% sepiolite powder activated by calcium chloride. Both experimental and simulation studies were conducted to assess its humidity-control performance. The experimental results indicate that gypsum-based humidity-control material has the property of absorbing moisture in high-humidity environments and releasing moisture in low-humidity environments. Moreover, both environmental temperature and relative humidity (RH) have an impact on the material’s humidity-control performance. At a relative humidity of 97.4%, the maximum equilibrium moisture content of the material is 0.225 g/g, which is 1.4 times that of the gypsum–silica gel humidity-control material and 4.5 times that of pure gypsum material. The simulation results indicate that gypsum-based humidity-control material effectively mitigates indoor relative humidity fluctuations and maintains indoor air relative humidity within a narrow range. Furthermore, the material has the potential to reduce building energy consumption. This is especially evident under climate conditions with large temperature and relative humidity differences between day and night, such as in Beijing, Paris, and Atlanta. The maximum potential energy-saving rate in Beijing can reach up to 19.31%.Keywords:humidity control;composite material;energy saving simulation;gypsum
Zifan Song,Zipeng Zhang,Xueting Zhang,Jingyang Liu,Wanjie Wang,Jianfeng Wang,Xiuxiu Jin
Switchable radiative cooling/heating holds great promise for mitigating the global energy and environmental crisis. Here, we reported a cost-effective, high-strength Janus film through surface optical engineering waste paper with one side decorated by a hydrophobic polymeric cooling coating consisting of micro/nanopore/particle hierarchical structure and the other side coated with hydrophilic MXene nanosheets for heating. The cooling surface demonstrates high solar reflectivity (96.3%) and infrared emissivity (95.5%), resulting in daytime/nighttime sub-ambient radiative cooling of 6°C/8°C with the theoretical cooling power of 100.6 and 138.5 W m −2 , respectively. The heating surface exhibits high solar absorptivity (83.7%) and low infrared emissivity (15.2%), resulting in excellent radiative heating capacity for vehicle charging pile (~6.2°C) and solar heating performance. Impressively, the mechanical strength of Janus film increased greatly by 563% compared with that of pristine waste paper, which is helpful for its practical applications in various scenarios for switchable radiative thermal management through mechanical flipping. Energy-saving simulation results reveal that significant total energy savings of up to 32.4 MJ m −2 can be achieved annually (corresponding to the 12.4% saving ratio), showing the immense importance of reducing carbon footprint and promoting carbon neutrality.
Passive daytime radiative cooling (PDRC) technology offers a green, sustainable solution for maintaining thermal comfort in buildings and is beneficial for the achievement of global carbon neutrality targets. Although significant improvements have been made to optimize the cooling performance of PDRC materials, the problems of nonrenewable and optimized cooling performance inevitably result in nighttime overcooling in practical complex environments. Herein, an all-in-one cast-molded hydrophobic silicon dioxide-phase change microcapsule/gelatin-hydroxyethyl cellulose (SiO2–PCC/GEL-HEC) composite aerogel was prepared by a simple directional freezing method. The resultant material displays excellent PDRC performance with high solar reflectance (92.61%) and high atmospheric transparent window emissivity (95.47%). Outdoor measurements show that under sunlight with an average intensity of 726.9 W·m–2, achieving an average of 4.3 °C of sub-ambient cooling; at night, it maintains temperature comfort through the exothermic phase change of the PCC in the composite aerogel, with an average temperature difference of 0.78 °C, solving the defects of overcooling at night. Promisingly, the excellent thermal insulation and heat preservation performance effectively prevent heat backflow and maintain thermal stability. The high water contact angle (152.3°) provides a self-cleaning performance to resist accidental soiling in outdoor applications, ensuring good PDRC performance. An energy saving simulation of potential cooling and heating shows that the use of hydrophobic SiO2–PCC/GEL-HEC composite aerogel only as a building exterior roof can save 5.27% of energy consumption in the summer compared to the building baseline. The prepared composite aerogel provides a simple and effective design solution for thermal comfort management of radiative coolers, which is expected to contribute to energy savings in building thermal comfort and address global climate change and energy consumption in a green and sustainable way.
危险品化学品经营许可证（带存储）