Nasal surfaces remove water vapor: camel

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The nasal surfaces of camels help conserve water by using hygroscopic properties to remove water from air during exhalation.

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Recapturing gray water in buildings, limiting evaporation from open storage ponds, more efficient irrigation systems, recapturing water used in industrial processes.

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The nasal surfaces of a dromedary camel help conserve water when the camel is dehydrated, by cooling and extracting water from exhaled air. During hot desert days, this nasal heat exchange mechanism also helps protect the camel's brain from overheating.

How does it work? Heat and water exchange take place primarily along the turbinate structures of the camel's nasal passages. Turbinates are spongy nasal bones, and the camel's turbinates are highly scrolled, providing narrow air passageways and a large surface area for water and heat exchange. Measurements suggest that camels have more than 1000 cm2 of nasal surface area, whereas the human nasal cavity may have a total surface area of only 160-180 cm2. Normally, the surface of the turbinates is covered with moist secretions, which help humidify dry desert air as the camel breathes in and remove water vapor as the camel breathes out. However, as the camel becomes dehydrated and the nasal passages dry out, this simple mechanism works in reverse: the nasal surfaces give off water during inhalation and take up water as air is exhaled.

The camel's body temperature may fluctuate several degrees Celsius during one day. Therefore, a dehydrated camel only cools and desaturates exhaled air during cooler nighttime temperatures. During hot desert days, protecting the brain from overheating becomes more important than conserving water, and the camel exhales saturated air at approximately body temperature. High blood flow heats the turbinates during the day, cooling the arterial blood flowing to the brain in the process.

How will it benefit society? According to a report from the United Nations Environment Programme, severe water shortages will affect 4 billion people by 2050. Looking to the dromedary camel's water conservation strategies for inspiration, we could design solutions to limit evaporation from water storage ponds, design more efficient irrigation systems, and learn how to best minimize loss and recapture water used in industrial processes.

Excerpt

"We have found that camels can reduce the water loss due to evaporation from the respiratory tract in two ways: (1) by decreasing the temperature of the exhaled air and (2) by removal of water vapour from this air, resulting in the exhalation of air at less than 100% relative humidity (r.h.). Camels were kept under desert conditions and deprived of drinking water. In the daytime the exhaled air was at or near body core temperature, while in the cooler night exhaled air was at or near ambient air temperature. In the daytime the exhaled air was fully saturated, but at night its humidity might fall to approximately 75% r.h. The combination of cooling and desaturation can provide a saving of water of 60% relative to exhalation of saturated air at body temperature. The mechanism responsible for cooling of the exhaled air is a simple heat exchange between the respiratory air and the surfaces of the nasal passageways. On inhalation these surfaces are cooled by the air passing over them, and on exhalation heat from the exhaled air is given off to these cooler surfaces. The mechanism responsible for desaturation of the air appears to depend on the hygroscopic properties of the nasal surfaces when the camel is dehydrated. The surfaces give off water vapour during inhalation and take up water from the respiratory air during exhalation. We have used a simple mechanical model to demonstrate the effectiveness of this mechanism." (Schmidt-Nielsen and others 1981:305)

About the inspiring organism

dromedary
Camelus dromedarius Linnaeus, 1758
[Dromedary]

IUCN Red List Status: Unknown
Habitat(s): Desert

Some organism data provided by: ITIS: The Integrated Taxonomic Information System
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Bioinspired products and application ideas

Application Ideas: Recapturing gray water in buildings, limiting evaporation from open storage ponds, more efficient irrigation systems, recapturing water used in industrial processes.

Industrial Sector(s) interested in this strategy: Building, water storage, agriculture, manufacturing

References

Schmidt-Nielsen, K.; Schroter, R. C.; Shkolnik, A. 1981. Desaturation of Exhaled Air in Camels. Proceedings of the Royal Society of London. Series B, Biological Sciences. 211(1184): 305-319.

Nasal surfaces remove water vapor: camel

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