MIT researchers have created a cooling system which is made of inexpensive materials and requires no fossil fuel to work. This innovation will soon provide much needed cheap and reliable cooling for off-grid locations. The invention also works as a high-tech version of a parasol by allowing emission of heat at a mid-infrared range of light. These wavelengths of light can pass through the atmosphere and radiate into the cold outer space. In an initial test, the device already achieved a cooling of 6 degree Celcius below the ambient temperature.
The scientists estimate that it can increase to as much as 20 degrees Celcius. Scientists have tried to design a passive cooling system earlier as well which can radiate heat in the form of mid-infrared wavelengths of light. The past systems have been based on complex engineered photonic devices and make it expensive and difficult to mass produce. MIT’s team changed the idea by putting an umbrella over it and also supplementing it with insulation to protect from the ambient air temperature.
Bikram Bhatia, the co-creator of the device, said, “We built the setup and did experiments outdoors on an MIT rooftop. It was done using very simple materials, and clearly showed the effectiveness of the system.” Evelyn Wang, collaborator, and professor of mechanical engineering and department said, “It’s kind of deceptively simple. By having a separate shade and an emitter to the atmosphere — two separate components that can be relatively low-cost — the system doesn’t require a special ability to emit and absorb selectively. We’re using angular selectivity to allow blocking the direct sun, as we continue to emit the heat-carrying wavelengths to the sky.”
The approached used by the team makes the system ideal for more localized applications. Wang said, “This would be useful for refrigeration applications, such as food storage or vaccines.” Even if the system cannot bring the temperature down to the needed levels, it can still reduce the loads on the electrical refrigeration systems. It can also be used in some concentrated photovoltaic systems for preventing overheating. The team is working to improve the insulation of the device to achieve the perfect balance and prevent it from heating up from surrounding air and also not blocking its ability to radiate the heat. The team has already applied for patents on the invention.
