Articles
Evaluating the role of the perforation cross-section profile on the gas exchange through microperforated packages
Article number
1396_51
Pages
385 – 394
Language
English
Abstract
The main objective of this work was to evaluate the impact of the perforation cross-section geometry on the gas transport of microperforated modified atmosphere packages.
A 3D numerical model, that considers a space-time and pressure dependence of the gas composition, was adapted to simulate the gas concentration profiles around the microperforation, considering both diffusive and convective flows.
The model was implemented in COMSOL Multiphysics® for eight case studies consisting in microperforations with different cross-section geometries (circular, squared, triangular, trapezoidal, and the actual geometry of a microperforation obtained from SEM images), maintaining the same minimal area (7420.6 µm2). A custom-built experimental system composed by two chambers was designed to measure the gas transport through microperforations.
The upper chamber was filled with a 20.95% CO2-0.05% O2-79% N2 gas mixture, while the lower chamber was initially filled with air.
The perforation was attached between the two chambers, and a CO2 sensor was placed in the lower chamber.
The results for the actual cross-section geometry were successfully verified with experimental data.
In this case, the final concentration of CO2 was 12% and the root mean squared error of the simulation values was 0.14%. The model predictions revealed the importance of properly characterizing the cross-section profile, since the CO2 concentration at the end of the simulations (216 h) ranged from 10 to 13%, depending on the geometry.
The influence of slight variations in the atmospheric pressure on gas exchange through microperforations was also analysed.
For this purpose, two cases were considered: constant and variable atmospheric pressure according to the data recorded experimentally.
From the results obtained with these simulations it can be concluded that small fluctuations in the atmospheric pressure affect the gas exchange through the microperforation since the concentration of CO2 at constant pressure was 3% less than at variable pressure.
A 3D numerical model, that considers a space-time and pressure dependence of the gas composition, was adapted to simulate the gas concentration profiles around the microperforation, considering both diffusive and convective flows.
The model was implemented in COMSOL Multiphysics® for eight case studies consisting in microperforations with different cross-section geometries (circular, squared, triangular, trapezoidal, and the actual geometry of a microperforation obtained from SEM images), maintaining the same minimal area (7420.6 µm2). A custom-built experimental system composed by two chambers was designed to measure the gas transport through microperforations.
The upper chamber was filled with a 20.95% CO2-0.05% O2-79% N2 gas mixture, while the lower chamber was initially filled with air.
The perforation was attached between the two chambers, and a CO2 sensor was placed in the lower chamber.
The results for the actual cross-section geometry were successfully verified with experimental data.
In this case, the final concentration of CO2 was 12% and the root mean squared error of the simulation values was 0.14%. The model predictions revealed the importance of properly characterizing the cross-section profile, since the CO2 concentration at the end of the simulations (216 h) ranged from 10 to 13%, depending on the geometry.
The influence of slight variations in the atmospheric pressure on gas exchange through microperforations was also analysed.
For this purpose, two cases were considered: constant and variable atmospheric pressure according to the data recorded experimentally.
From the results obtained with these simulations it can be concluded that small fluctuations in the atmospheric pressure affect the gas exchange through the microperforation since the concentration of CO2 at constant pressure was 3% less than at variable pressure.
Authors
S. Vega-Diez, M.L. Salvador, J. González-Buesa
Keywords
simulation, 3D model, microperforation, modified atmosphere, packaging
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