The novel material, which can be used on rooftops and works both during the day and at night, is an electricity-free cooling system.
An cheap “radiative cooler” coating material has been developed by researchers at the Indian Institute of Technology, Guwahati, as a non-electric replacement for air conditioning.
Officials claim that this material is an electricity-free cooling system because it can be sprayed to rooftops and operates both during the day and at night as a substitute for traditional air conditioners.
“Systems that use passive radiative cooling work by releasing heat that has been absorbed from the environment as infrared radiation, which can pass through the atmosphere before being emitted into the frigid outer space.The majority of passive radiative coolers only work at night.These coolers must also reflect the complete sun radiation in order to function during the day” IIT Guwahati research student Ashish Kumar Chowdhary remarked.
“These cooling devices have not yet been able to chill the room sufficiently during the day.We are prepared to address these problems and release an accessible, more effective radiative cooling system that can run continuously” Added he.
Their novel idea has been published by IOP Publishing in the UK’s Journal of Physics D: Applied Physics.
According to Debabrata Sikdar, assistant professor in the department of electronics and electrical engineering at IIT Guwahati, “Designing a passive radiative cooler for daytime operation is more challenging due to the simultaneous requirement of high reflectance in entire solar spectral regime and high emissivity in the atmospheric transmittance window”.
“One of the better alternatives to the typical air conditioning systems used to cool buildings and automobiles in nations with hot climates, like India, may be these radiative coolers, which operate without the need for external energy sources.Radiative cooling is a special technique that cools an object on Earth by dispersing surplus heat into the incredibly cold universe, in contrast to conventional cooling technologies that dump the waste heat into the surroundings” Added he.
Once the large-scale prototypes are created and tested for operational stability and endurance under various climatic conditions, the team says they hope to see this on the market.Now, they are putting effort into this.
“The material must reflect the solar and atmospheric radiations striking it in order for a radiative cooler to function throughout the day.Conventional coolers do not function during the day because their materials absorb more solar energy and reflect less of it.While polymer-based passive radiative coolers can be used to provide daytime cooling, oxidation destroys the polymers, resulting in a limited lifespan” explained Chowdhary.
“We thought about employing silicon dioxide and aluminium nitride thin films to solve this.The wavelength range of solar and atmospheric radiations are matched by the low optical density of these materials.But they have a high optical density at wavelengths where there is atmospheric transmission.When optical density is high, radiations penetrate a medium more slowly and are absorbed more fully.The substance emits all absorbed radiations like a black body to maintain thermal equilibrium”,Added he.