Highly viscous non-Newtonian xanthan gum solutions processed through a novel twisted double tape static mixer for improved mixing efficiency

Xanthan gum solutions, particularly at 1.0 wt. %, exhibit high viscosity, strong shear-thinning behavior, and viscoelastic properties, making their homogenization with conventional static mixers difficult. Efficient mixing of such non-Newtonian fluids is critical in food processing, pharmaceuticals, and biotechnology, motivating the development of a novel twisted double tape static mixer (TDSM) to address this challenge. The proposed design incorporates paired twisted blades to enhance fluid deformation and promote uniform scalar transport under laminar flow conditions. A comprehensive parametric investigation was conducted to examine the effects of tape twist pitch (9, 12, 15 cm), inter-element gap (H/2, H/3, H/4; H = 8 cm), and blade thickness (1 mm, 3 mm) on mixing performance, evaluated in terms of mixing index and pressure drop at an inlet velocity of 0.5 m/s. Among 18 tested configurations with 1.0 wt. % XG, the optimal design, 12 cm twist pitch, 4 cm inter-element spacing, and 3 mm blade thickness, achieved a mixing index of 0.977 with a pressure drop of 12.320 kPa. Thicker blades improved mixing efficiency by 1.7%–2.2% across all cases but increased pressure drop by 12.4%–13.8%, while reducing the inter-element gap from 4 to 2 cm decreased the mixing index by 12.1%. These results demonstrate that tailoring mixer geometry to the rheological properties of xanthan gum significantly enhances mixing efficiency, with the TDSM offering a novel and practical solution for processing highly viscous, shear-thinning fluids in industrial applications.