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A Mass Transfer Model of Ethanol Emission from Thin Layers of Corn Silage
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: Transactions of the ASABE. 53(6): 1903-1909. (doi: 10.13031/2013.35800) @2010Authors: H. M. El-Mashad, R. Zhang, T. Rumsey, S. Hafner, F. Montes, C. Alan Rotz, V. Arteaga, Y. Zhao, F. M. Mitloehner
Keywords: Corn silage, Dairy farms, Ethanol emissions, Mass transfer coefficient, Modeling, VOC emissions
A mass transfer model was developed and validated to predict ethanol emission from thin layers of corn silage. The model was developed using experimental data collected from silage placed in a wind tunnel under different temperatures and air velocities. Data from the wind tunnel experiments were used to derive a multiple regression equation that related the overall mass transfer coefficient of ethanol to temperature and air velocity. Evaluation of the model was done using data collected from experiments conducted in a controlled environmental chamber. Ethanol emission was determined from the ventilation rate of the environmental chamber and ethanol concentration in the chamber exhaust over a 24 h period, measured using a photoacoustic gas analyzer. Ethanol concentration in the silage was also monitored throughout the duration of each experiment. Predicted ethanol emission rates were strongly correlated (R2 = 0.94) with values measured in the environmental chamber. A high correlation (R2 = 0.96) was also found between predicted and measured ethanol concentrations in the silage. The model was used to estimate ethanol emission rates from thin layers of lightly packed silage on a dairy farm in California. Model predictions indicate that most of the ethanol contained in the silage could be emitted in the first 10 h after exposing the silage to ambient air temperature (18C to 35C) and air velocity (0.1 to 2.0 m s-1).
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