Subj : Thermal cloak passively keeps electric v To : All From : ScienceDaily Date : Tue Jul 11 2023 22:30:30 Thermal cloak passively keeps electric vehicles cool in the summer and warm in the winter Date: July 11, 2023 Source: Cell Press Summary: When an electric vehicle is parked outside, its temperature can swing wildly from day to night and season to season, which can lead to deterioration of the battery. To dampen these fluctuations and extend the battery's lifespan, researchers have designed an all-season thermal cloak that can cool an electric vehicle by 8DEGC on a hot day and warm it by 6.8DEGC at night. The cloak, made predominantly of silica and aluminum, can do so passively without outside energy input and operates without any modification between hot or cold weather. Facebook Twitter Pinterest LinkedIN Email ========================================================================== FULL STORY ========================================================================== When an electric vehicle is parked outside, its temperature can swing wildly from day to night and season to season, which can lead to deterioration of the battery. To dampen these fluctuations and extend the battery's lifespan, researchers have designed an all-season thermal cloak that can cool an electric vehicle by 8DEGC on a hot day and warm it by 6.8DEGC at night. The cloak, made predominantly of silica and aluminum, can do so passively without outside energy input and operates without any modification between hot or cold weather. This prototype is described July 11 in the newly launched Device, an application-oriented sister journal to Matter,Joule, and Cell. "The thermal cloak is like clothes for vehicles, buildings, spacecrafts, or even extraterrestrial habitats to keep cool in summer and warm in winter," says senior author Kehang Cui, a materials scientist at Shanghai Jiao Tong University. To dampen natural temperature fluctuations, the cloak isolates the car -- or any other object beneath it -- from the surrounding environment. The cloak has two components: an outer layer which efficiently reflects sunlight and an inner layer that traps heat inside. Whatever heat the outer layer does absorb is emitted in such a way that it can be readily dissipated to outer space. This design earns it the name of Janus thermal cloak, inspired by the two-faced Roman god Janus. "The cloak works basically the same way the earth cools down, through radiative cooling" says Cui. "The earth is covered by the atmosphere, and the atmosphere is transparent to a certain range of electromagnetic energy we radiate." While this process is desirable in the summer, it would make the car colder during winter months. "You have to develop something that can turn on and off by itself without external energy input, and that's extremely difficult," says Cui. Cui and his team designed the cloak to automatically counteract this effect in the winter. The cloak employs an effect called "photon recycling" - - essentially, any energy that is trapped under the cloak will bounce back and forth between the car and cloak rather than escape to the surroundings outside. To assess the performance of the thermal cloak, the researchers conducted tests on electric vehicles parked outside under typical ambient conditions in Shanghai. While the cabin temperature of an uncovered car reached 50.5DEGC at mid-day, the cabin of the cloak-covered car reached 22.8DEGC -- 27.7DEGC lower than the uncovered car and 7.8DEGC lower than the temperature outside. At midnight, the covered car stayed 6.8DEGC higher than the temperature outside, never dropping below 0DEGC. "This is the first time that we could achieve warming above the ambient temperature by almost 7DEGC during winter nights," says Cui. "This is also kind of surprising to us -- there's no energy input or sunshine and we can still get warming." The outer component of the cloak is made of thin fibers of silica that were then coated in flakes of hexagonal boron nitride, a ceramic material similar to graphite that enhances the fibers' solar reflectivity. These fibers are then braided and woven together into a fabric and adhered to the inner layer, which is made of aluminum alloy. The team purposefully designed the cloak to make scaling up production easier in the future. For example, using thinner silica fibers would have increased solar reflectivity, but they would be weaker and couldn't be made with high- volume, industrial-level production techniques already available. In addition, the materials used, including the aluminum, silica, and boron nitride, are all low-cost and make the cloak lightweight, durable, and fire-retardant. * RELATED_TOPICS o Matter_&_Energy # Vehicles # Physics # Automotive_and_Transportation # Quantum_Physics o Earth_&_Climate # Energy_and_the_Environment # Renewable_Energy # Environmental_Issues # Environmental_Science * RELATED_TERMS o Battery_electric_vehicle o Season o Temperature o Fuel_cell o 2005_Atlantic_hurricane_season o Electric_power o Hybrid_vehicle o Hurricane_Camille ========================================================================== Print Email Share ========================================================================== ****** 1 ****** ***** 2 ***** **** 3 **** *** 4 *** ** 5 ** Breaking this hour ========================================================================== * Revolutionary_Electric_Artificial_Muscles * Age_of_Universe:_26.7,_Not_13.7,_Billion_Years * City_Ground_Is_Deforming:_Buildings_Aren't_Ready * The_Sound_of_Silence?_People_Hear_It * 36-Million-Year_Geological_Cycle_Drives_... * Six_Foods_to_Boost_Cardiovascular_Health * Cystic_Fibrosis:_Lasting_Improvement * Artificial_Cells_Demonstrate_That_'Life_... * Advice_to_Limit_High-Fat_Dairy_Foods_Challenged * First_Snapshots_of_Fermion_Pairs Trending Topics this week ========================================================================== PLANTS_&_ANIMALS Nature Botany Endangered_Plants EARTH_&_CLIMATE Climate Sustainability Water FOSSILS_&_RUINS Early_Climate ========================================================================== Strange & Offbeat ========================================================================== PLANTS_&_ANIMALS Bees_Make_Decisions_Better_and_Faster_Than_We_Do,_for_the_Things_That_Matter_to Them These_Lollipops_Could_'Sweeten'_Diagnostic_Testing_for_Kids_and_Adults_Alike Why_There_Are_No_Kangaroos_in_Bali_(and_No_Tigers_in_Australia) EARTH_&_CLIMATE Turning_Old_Maps_Into_3D_Digital_Models_of_Lost_Neighborhoods Squash_Bugs_Are_Attracted_to_and_Eat_Each_Other's_Poop_to_Stock_Their Microbiome How_Urea_May_Have_Been_the_Gateway_to_Life FOSSILS_&_RUINS Giant_Stone_Artefacts_Found_on_Rare_Ice_Age_Site_in_Kent,_UK Fossils_Reveal_How_Ancient_Birds_Molted_Their_Feathers_--_Which_Could_Help Explain_Why_Ancestors_of_Modern_Birds_Survived_When_All_the_Other_Dinosaurs Died Apex_Predator_of_the_Cambrian_Likely_Sought_Soft_Over_Crunchy_Prey Story Source: Materials provided by Cell_Press. Note: Content may be edited for style and length. ========================================================================== Journal Reference: 1. Huaxu Qiao, Zhequn Huang, Jianming Wu, Jie Shen, Heng Zhang, Qixiang Wang, Wen Shang, Wei Tang, Tao Deng, Hongxing Xu, Kehang Cui. Scalable and durable Janus thermal cloak for all-season passive thermal regulation. Device, 2023; 100008 DOI: 10.1016/j.device.2023.100008 ========================================================================== Link to news story: https://www.sciencedaily.com/releases/2023/07/230711133111.htm --- up 1 year, 19 weeks, 1 day, 10 hours, 50 minutes * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3) .