2024-07-13 14:04:19
Scientists at the University of Notre Dame have developed a coating that blocks heat without affecting the passage of light. The coating can be placed on windows, glass doors and even cars to reduce the temperature by up to 7.2 degrees Celsius. This breakthrough could cut air conditioning cooling costs by more than a third, according to researchers.
Window coatings on the market are designed to block ultraviolet light and heat-generating infrared light from the sun. However, these filters are optimized for light that directly hits the window. The proposed coating is built from photonic structures that allow the selective transmission of the solar spectrum in a wide range of angles.
“The angle between sunlight and the window is always changing. At midday, often the hottest time of the day, the sun’s rays enter vertically installed windows at oblique angles,” said Tengfei Luo, a professor of energy studies at the University of Notre Dame and an author on the study. “Our coating maintains functionality and efficiency regardless of the sun’s position in the sky.”
The coating is achieved stacking ultra-thin layers of silica, alumina and titanium oxide on a glass baseThe researchers used quantum computing to define the configuration in which they should mix these layers, so as to maximize light and reduce the passage of heat-producing wavelengths. They then added a silicon polymer that reflected radiation outwardswhich improved the cooling power.
According to the results, the coating It is capable of reducing the temperature between 5.4 and 7.2 degrees Celsius.
A coating that reduces heat and represents energy savings
Researchers are increasingly interested in developing optical filters that can selectively control light at specific wavelengths. These filters have applications in a variety of fields, including solar cells (photovoltaics), light-emitting diodes (LEDs), and sensors.
Planar multilayer (PML) photonic structures offer a promising approach to design such filters. These structures consist of stacked layers of different materials capable of bending lightBy carefully choosing these materials and their thicknesses, scientists can design PML filters that selectively transmit or reflect light according to its wavelength.
For this study, the researchers have developed a technique called “quantum computing assisted active learning scheme.” This uses Machine learning to create a map of possible solutionsconsidering the relationship between different filter designs and their performance. A software will then find the best solution with the help of quantum computing to boost the number of calculations.
The end result is a filter that blocks unwanted ultraviolet (UV) and near-infrared (NIR) light from the sun, but allows visible light to pass through, regardless of the angle at which it hits the window. By applying a thin layer of polydimethylsiloxane (PDMS), the filter will radiate heat back into the atmosphere.
«Like polarized sunglasses, our coating decreases the intensity of incoming light, but unlike sunglasses, our coating remains clear and effective even when you tilt it at different angles.»
Tengfei Luo, professor of energy studies at the University of Notre Dame.
The research team tested the physical properties of these structures and confirmed their ability to significantly reduce heat build-up within an enclosure (from 5.4°C to 7.2°C). In addition, the study It estimates an annual energy saving of approximately 97.5 MJ/m²The results have been published in the journal Cell Reports Physical Science and would lay the foundations for designing a range of materials with complex properties.