Evaluation of NETmix geometrical properties on gas-liquid mass transfer performance

• Published in: Journal of environmental chemical engineering Vol. 12; no. 5; p. 113771
• Main Authors: Marrocos, Paulo H., Fernandes, Isabel S., Lopes, José C.B., Dias, Madalena M., Santos, Ricardo J., Vilar, Vítor J.P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2024
• Subjects: Computational fluid dynamics; Design optimization; Gas-liquid mass transfer; Interfacial area generation; NETmix static mixer; Gas-liquid mass transfer; Computational fluid dynamics; Interfacial area generation; NETmix static mixer; Design optimization
• ISSN: 2213-3437
• DOI: 10.1016/j.jece.2024.113771

The unit cells of the micro/meso-structured static mixer NETmix consist of cylindrical chambers connected by prismatic half-channels. These elements are defined by their characteristic geometrical properties: chamber diameter, channel length and width, as well as depth. This study analyses the effect of two geometrical properties, channel length and depth, on the gas-liquid mass transfer performance of the NETmix. Four NETmix plates were constructed with different dimensions to experimentally assess the volumetric mass transfer coefficients under different operating conditions. Coupling the experimental data with bidimensional computational fluid dynamics (CFD) simulations enabled a separate evaluation of the mass transfer coefficient and the specific interfacial area. Based on the simulation and an algorithmic image processing methodology, a model to describe the interfacial area generation phenomenon in the static mixer was proposed, resulting in a maximum deviation of 11 %. Although a reduction in the channel length from 4 mm to 1 mm decreased the interfacial area (a), the mass transfer coefficient (kL) increased by 27 %, leading to a global improvement in the volumetric mass transfer coefficient (kLa) by 12 %. Furthermore, reducing the NETmix depth value from 4 mm to 2 mm enabled a 31 % increase in the volumetric mass transfer coefficient. However, gas-liquid pressure drop measurements showed that each 1 % improvement in the gas-liquid mass transfer achieved by the depth reduction required a 10 % increase in energy consumption. [Display omitted] •NETmix channel length and depth effect on the gas-liquid mass transfer is assessed.•Channel length reduction improved volumetric mass transfer coefficients (kLa).•Depth reduction enhanced kLa at the expense of increased energy consumption.•2D CFD simulations described the interfacial area (a) generation mechanisms.•Proposed mechanistic model successfully predicts a with 11 % maximum deviation.