Modeling and Optimization of Mash Tun Flow

Transcription

1 Modeling and Optimization of Mash Tun Flow by Conor J. Walsh An Engineering Project Submitted to the Graduate Faculty of Rensselaer Polytechnic Institute in Partial Fulfillment of the Requirements for the degree of MASTER OF ENGINEERING Major Subject: MECHANICAL ENGINEERING Approved: Ernesto Gutierrez-Miravete, Thesis Adviser Rensselaer Polytechnic Institute Hartford, Connecticut December, 2013 i

2 Copyright 2013 by Conor J. Walsh All Rights Reserved ii

3 CONTENTS Modeling and Optimization of Mash Tun Flow... i LIST OF SYMBOLS... iv LIST OF FIGURES... v LIST OF TABLES... vi GLOSSARY... vii LIST OF KEYWORDS... viii ACKNOWLEDGMENT... ix ABSTRACT... x INTRODUCTION/BACKGROUND... 1 THEORY/METHODOLOGY... 2 RESULTS AND DISCUSSION... 4 CONCLUSIONS... 5 REFERENCES... 6 APPENDICES... 7 iii

4 LIST OF SYMBOLS iv

5 No table of figures entries found. LIST OF FIGURES v

6 No table of figures entries found. LIST OF TABLES vi

7 GLOSSARY vii

8 LIST OF KEYWORDS viii

9 ACKNOWLEDGMENT Type the text of your acknowledgment here. ix

10 ABSTRACT A mash tun is the device used when brewing beer that allows fermentable sugars to be extracted from malted grains (called mashing ). The grain is crushed, then allowed to soak in hot water in the tun for a proscribed period of time in order to activate enzymes in the malt, which in turn convert starches in the malt into sugars. The water is drained from the grains, and then more hot water is used to rinse the grains in order to extract further sugars. The mash tun must include a filter of some kind to allow for hot water to run through the grain and carry the sugar out while leaving the grain husks. For homebrewers, a popular design for filtering is the pipe manifold: a series of pipes with small holes or slits that allow water to enter, then exit the mash tun. This style of mash tun will be modeled in COMSOL and optimized alternatively for maximum sugar extraction or maximum uniformity of flow, given some parameters common to the average homebrewer. The COMSOL model will be validated by means of a prototype build and real-world testing. The advantages and disadvantages of various design modifications are not obvious or readily available to the average homebrewer and home mash tun designer. There are a number of parameters that can be varied during the mash tun build, and it is not at all clear how each factor affects the final device. Whether the goal is to design the tun to provide maximum extract efficiency or highest wort quality, a homebrewer would be well served to have an ideal design on which to base their own mash tun. x

11 INTRODUCTION/BACKGROUND On May 9, 2013, Alabama's Governor Robert Bently signed into law House Bill 9, making his state the 50 th to pass legislation legalizing the production of beer within the home. This event was considered by many to be long overdue, as Federal restrictions on homebrewing were repealed with H.R. 1337, passed in October of This final legal step also coincides with a recent increase in public interest in the United States in the homebrewing hobby, and contributes to the passage of homebrewing from the underground out into mainstream culture. This marks an ideal time for the homebrewing community to take advantage of these developments and bolster the beer-making craft with science and technology. This is not to say that no one in the community has yet pursued the scientific side of brewing; obviously, commercial breweries in the U.S. have been advancing in technical prowess since the end of Prohibition, and books such as Charlie Papazian's The Complete Joy of Homebrewing (1984) are testament to the existence of a technical approach to homebrewing for decades. To some extent, however, homebrewing is very much still an art. This project aims to move in the technical direction by utilizing the simulation capabilities of COMSOL Multiphysics, an easily-accessible and highly capable modeling program. In particular, this project will evaluate a mash tun, and will attempt to produce reliable technical results that can be used by any homebrewer. 1

12 THEORY/METHODOLOGY Following the mashing of malted grains, the water/sugar mixture that exits the mash tun is referred to as wort. This wort is boiled with hops, and then yeast is added in order to ferment the wort into beer. Other ingredients can be and often are added, but only four ingredients are required to make beer: water, malted grains, hops, and yeast. The mashing process contributes critically to the final taste, aroma, color, and mouthfeel of the beer, and provides an excellent opportunity to use science and technology to improve the homebrewing experience. The COMSOL model created for this project will be used to analyze two separate properties of the mash (grain-water mixture in a mash tun) that might interest the average homebrewer: mash efficiency and wort quality. High mash efficiency is an ideal goal of a homebrewer looking to save money or simply minimize waste, as a highly efficient mash produces a higher sugar output per grain input. For a specific beer recipe (for which the amount of sugar is a constant, this equates to less grain to buy and less wasted grain overall. Wort quality, on the other hand, has been found to relate to the overall uniformity of flow of hot water through the mash tun (Palmer p. 302). Uneven flow throughout the mash tun when draining or rinsing the wort will often result in over-extraction of certain areas of the grain bed, producing tannins (which provide an unwanted astringent taste, more often associated with wine) and other compounds that negatively impact taste. 2

13 Homebrewers have a limited ability to affect wort quality compared to the commercial brewer for example, they cannot improve the quality of ingredients over those already available to them in their area or, more recently, through a small number of internet retail providers. Further, they have a limited range of heating and cooling techniques and equipment available to them. Minimizing off-flavors during the mash is one of the few methods through which they can improve the quality of the wort, and thus the final beer. 3

14 RESULTS AND DISCUSSION The results of this project could potentially be published in the following technical journals and industry (homebrewing) magazines: The Journal of the Institute of Brewing Journal of the American Society of Brewing Chemists Technical Quarterly of the Master Brewers Association of the Americas BYO Magazine Zymurgy 4

15 CONCLUSIONS 5

16 REFERENCES de Lemos, Marcelo J.S.. Turbulence in Porous Media: Modeling and Applications, Second Edition. Elsevier Science and Technology Books, Inc., Books24x7. Web. Sep. 17, < Fox, Robert W., Philip J. Pritchard, and Alan T. McDonald. Introduction to Fluid Mechanics. 7 th ed. John Wiley and Sons, Inc., Palmer, John J. How to Brew. 3 rd ed. Brewers Publications, Spanos, T. J. T. The Thermophysics of Porous Media. Chapman and Hall/CRC, Vafai, Kambiz. Handbook of Porous Media, Second Edition. CRC Press, Xie, Liquan, ed. Modeling and Computation In Engineering II. CRC Press,

17 APPENDICES 7