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Journal of Non-Equilibrium Thermodynamics

Founded by Keller, Jürgen U.

Editor-in-Chief: Hoffmann, Karl Heinz

Managing Editor: Prehl, Janett / Paul, Raphael

Ed. by Michaelides, Efstathios E. / Rubi, J. Miguel

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Volume 42, Issue 1


The Nasal Geometry of the Reindeer Gives Energy-Efficient Respiration

Elisa Magnanelli
  • Corresponding author
  • Department of Chemistry, NTNU – Norwegian University of Science and Technology, N-7491 Trondheim, Norway
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Øivind Wilhelmsen
  • SINTEF Energy Research, N-7465 Trondheim, Norway
  • Department of Electrical Engineering and Renewable Energy, NTNU, N-7491 Trondheim, Norway
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Mario Acquarone
  • Norwegian College of Fishery Science, University of Tromsø – The Arctic University of Norway, N-9037 Tromsø, Norway
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  • De Gruyter OnlineGoogle Scholar
/ Lars P. Folkow
  • Department of Arctic and Marine Biology, University of Tromsø – The Arctic University of Norway, N-9037 Tromsø, Norway
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  • De Gruyter OnlineGoogle Scholar
/ Signe Kjelstrup
  • Department of Chemistry, NTNU – Norwegian University of Science and Technology, N-7491 Trondheim, Norway
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2016-07-14 | DOI: https://doi.org/10.1515/jnet-2016-0038


Reindeer in the arctic region live under very harsh conditions and may face temperatures below 233 K. Therefore, efficient conservation of body heat and water is important for their survival. Alongside their insulating fur, the reindeer nasal mechanism for heat and mass exchange during respiration plays a fundamental role. We present a dynamic model to describe the heat and mass transport that takes place inside the reindeer nose, where we account for the complicated geometrical structure of the subsystems that are part of the nose. The model correctly captures the trend in experimental data for the temperature, heat and water recovery in the reindeer nose during respiration. As a reference case, we model a nose with a simple cylindrical-like geometry, where the total volume and contact area are the same as those determined in the reindeer nose. A comparison of the reindeer nose with the reference case shows that the nose geometry has a large influence on the velocity, temperature and water content of the air inside the nose. For all investigated cases, we find that the total entropy production during a breathing cycle is lower for the reindeer nose than for the reference case. The same trend is observed for the total energy consumption. The reduction in the total entropy production caused by the complicated geometry is higher (up to -20 %) at more extreme ambient conditions, when energy efficiency is presumably more important for the maintenance of energy balance in the animal. In the literature, a hypothesis has been proposed, which states that the most energy-efficient design of a system is characterized by equipartition of the entropy production. In agreement with this hypothesis, we find that the local entropy production during a breathing cycle is significantly more uniform for the reindeer nose than for the reference case. This suggests that natural selection has favored designs that give uniform entropy production when energy efficiency is an issue. Animals living in the harsh arctic climate, such as the reindeer, can therefore serve as inspiration for a novel industrial design with increased efficiency.

Keywords: thermodynamics; Rangifer tarandus; transport; nose; breathing; reindeer; energy efficiency; entropy production


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About the article

Received: 2016-04-30

Revised: 2016-07-04

Accepted: 2016-06-17

Published Online: 2016-07-14

Published in Print: 2017-01-01

Citation Information: Journal of Non-Equilibrium Thermodynamics, Volume 42, Issue 1, Pages 59–78, ISSN (Online) 1437-4358, ISSN (Print) 0340-0204, DOI: https://doi.org/10.1515/jnet-2016-0038.

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