Thermal Performance of Aluminum and Glass Beer Bottles

Abstract

Aluminum beer bottles recently have been introduced as an alternative to traditional glass bottles or aluminum cans. Advertisements claim that the new aluminum bottles keep beer “colder longer” than glass bottles. Because the thermal conductivity of aluminum is over 150 times that of typical soda-lime glass, and because the bottle wall is thinner, this claim appears counterintuitive. In this investigation, the thermal performance of commercially available aluminum and glass beer bottles was examined using experimental, analytical, and computational methods. It was found that when exposed to ambient air, glass and aluminum bottles perform in a nearly identical manner with respect to keeping their contents cold. Each bottle showed an approximately 15°C temperature rise over a 2.7-hour period. Heat transfer is controlled by natural convection and thermal radiation at the outer bottle surface; hence, the difference in thermal conductivity between the bottles has no significant impact on the temperature transient. Computational simulations also predict that when an aluminum bottle is immersed in an ice-water bath, the liquid cools more quickly than in glass due to the lower thermal resistance of the aluminum versus the glass; when held in the hand, the glass bottle allows the liquid to warm more slowly than the aluminum bottle.

ACKNOWLEDGMENTS

The experimental portion of this study was designed and performed by Natasha Epps, Caitlin Hogan, Amanda Levinson, Tom Scida, and David Wright. Their contribution to this work is gratefully acknowledged. The authors also are grateful to Jeff Vavro, Pittsburg Brewing Company, and Ed Martin, CCL Container, for providing background information on both soda-lime glass and aluminum bottles and for their constant encouragement during the course of this work. Ed Martin also supplied unused aluminum bottles and starting slugs. Mark Goda, CCL Container, provided helpful technical information about the exterior bottle coating. The identification of any manufacturer and/or product in this paper does not imply endorsement or criticism by the authors or Loyola College.

Notes

^a The emissivities of the bottle surfaces were determined experimentally.

^b The outer surface of the aluminum bottle is covered with a thin polymer layer, which causes the emissivity to be considerably higher than that normally attributed to clean aluminum.