Carbon dioxide in fermenting beer - Part II

J. Delente, C. Akin, E. Krabbe, and K. Ladenburg

Abstract
Yeast cells are heavier than wort and settle with other solids at the bottom of the fermenter. This causes the formation of CO2 bubbles which loosen the sediment layer and then draw liquid and yeast cells in their wake all the way to the top. In addition, the bubbles cause a liquid circulation pattern which will homogenize the fermenter contents. The most logical shape for a beer fermenter was found to be an upright cylinder with a cone bottom with cooling in the walls, where the warmest zone in the center is carried by liquid motion to the cooling walls, and where the sediment gathers at the apex of the cone. At the end of fermentation, CO2 can be injected right above the apex to facilitate the heat transfer by duplicating natural agitation.