Common campfire build confirmed as best

A structure of roughly equal height and width produces hottest flames, calculations show


HOT STUFF  Heaps of firewood or charcoal that are as tall as they are wide make the hottest fires. Fires built tall or squat burn cooler, new calculations show. 

Eric Dufresne/Wikimedia Commons (CC BY 2.0)

Summer vacations are so close one can almost smell the smoke from marshmallow-toasting campfires, bonfires on the beach, and, of course, classic backyard barbecues. What’s even better: Those imminent holiday blazes may require little thought, according to a new study.

Humans tend to build very efficient fires, perhaps unwittingly, says physicist Adrian Bejan of Duke University. And he has crunched the numbers to back up that assertion.

Across cultures, countries and eras, people have built fires by piling wood or other fuel in pyramid- or cone-shaped structures that are about as tall as they are wide at the base, Bejan says. Using back-of-the-envelope calculations of how air and heat flow through structures, he argues that fires with those proportions produce the hottest flames for their volume of fuel. Fires that are relatively tall or short compared with their width, lose more of their heat, he says.

The calculations, appearing June 8 in Scientific Reports, suggest no scout handbooks are needed for those leisurely summer blazes.

Editor’s Note: This article was updated on June 17, 2015, to correct the photo credit.

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