Refrigeration system without energy consumption to reinforce the air conditioning or preserve food

It is feasible to cool without relying on electricity, natural gas or other fuels or traditional energy sources. It is enough to take good advantage of evaporation, thermal insulation and processes that allow heat to be radiated.

As the world warms, the use of energy-intensive air conditioning systems is projected to increase sharply. This increased use will put an extra burden on existing power grids and will not be useful for places where power supply or other alternative sources of energy do not reach, or which is precarious.

The innovative system developed by the team of Zhengmao Lu, from the Massachusetts Institute of Technology (MIT) in the United States, offers a way to use passive refrigeration to preserve food and complement conventional air conditioners in buildings, without requiring energy and needing only a little water.

The system, which combines radiative cooling, evaporative cooling and thermal insulation, can be accommodated on fairly thin plates reminiscent of solar panels.

The system can lower the temperature to about 9 degrees Celsius below the original room temperature. That drop is enough to allow food to be stored safely for 40 percent longer in very humid conditions. And it can triple safe storage time in dry conditions.

Test of the new system. On the left, the complete device, combining evaporative cooling, radiation cooling and insulation. On the right, a version of the device that only uses evaporative cooling. By running both versions, you can compare the difference in cooldown level achieved by each. The cooling achieved by the full device far exceeds that achieved by the incomplete. (Photo: courtesy of Zhengmao Lu / MIT. CC BY-NC-ND 3.0)

Although more research is needed to reduce the cost of one of the system’s key components, the researchers say that, over time, this system could play an important role in meeting the cooling needs of many parts of the world where of electricity or the like limits the use of conventional cooling systems.

The system consists of three layers of material that together provide cooling as water and heat pass through the device. In practice, the device could be made in the shape of a conventional solar panel and installed in a similar way, only instead of generating electricity, it would directly provide cooling, for example by acting as the roof of a food storage container. Or it could be used to send cold water through pipes to cool parts of an existing air conditioning system and improve its efficiency.

The only maintenance that the new system needs is to add water for evaporation, but consumption is so low that it only needs to be done once every four days in the hottest and driest areas, and only once a month in the most humid areas. .

Lu and his colleagues present the details of their new technological advance in the academic journal Cell Reports Physical Science, under the title “Significantly enhanced sub-ambient passive cooling enabled by evaporation, radiation, and insulation.” (Font: NCYT by Amazings)