Passive Cooling System Inspired by Camels

Innovation: Academia

MIT

2020

Image: Wolfgang Hasselmann / Unsplash / CC BY SA - Creative Commons Attribution + ShareAlike

Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

Search this Function

Capture, Absorb, or Filter Liquids

The most common liquid used by living systems is water, which they require to survive. But there are many other liquids that provide nourishment, play a role in defense mechanisms, or serve other purposes. Water varies in its availability; it is sometimes plentiful and sometimes very scarce or only available as fog or mist. To minimize the energy required to capture, absorb, or filter liquids, living systems have strategies that take advantage of the unique properties of the given liquid. For example, water moves from a gaseous to liquid state when it encounters a surface colder than the air. Plants in forests that experience fog and clouds more than rain have strategies that condense liquid water from moist air.

Search this Function

Cooling system from MIT uses an evaporation-insulation cooling design that eliminates power usage.

Benefits

Sustainable
Reduced energy usage
Reduced waste

Applications

Pharmaceuticals
Food storage
HVAC systems

UN Sustainable Development Goals Addressed

Goal 3: Good Health & Wellbeing
Goal 11: Sustainable Cities & Communities
Goal 12: Responsible Production & Consumption

The Challenge

Biological samples and food products are often stored in refrigeration, which makes them vulnerable to equipment malfunction and oftentimes leads to decomposition over time. In addition, shipping these items in a refrigerated vessel or on dry ice can be costly and uses excessive materials.

Innovation Details

The cooling system is made of two layers. The inner layer is made of a hydrogel, from which water can readily evaporate, similar to sweat glands. The outer layer is an aerogel, which keeps out external heat, but allows the water vapor to pass through, similar to camel fur. The water vapor has a cooling effect as it increases the time it takes for the warm ambient temperature to reach the contents within the cooling system. The system is set up so that the hydrogel can be easily rehydrated. The entire material is less than a half-inch thick and can provide cooling of more than 7 degrees Celsius for five times longer than just the hydrogel alone.

Biological Model

Camels have a thick layer of insulating fur that reduces the amount moisture lost to the desert heat, which protects them from dehydration.

See Related Strategy

close up photograph of the fur of a brown camel

Biological Strategy

How a Camel’s Fur Coat Keeps It Cool

Dromedary camel

Camel fur and sweat glands combine to form a powerful temperature management system.

References

Journal article

Passive Sub-Ambient Cooling from a Transparent Evaporation-Insulation Bilayer

Joule

embedly preview

AskNature