Rheological Characterization and Flow Modeling of Mixed Flour in an Industrial Food Processing Plant

Le-ol Anthony Kpegele¹, Stanislaus Chinemerem Philip²

¹Sr. Lecturer, Department of Mechanical Engineering, Rivers State University, Port Harcourt, Nigeria.

²Student, Department of Mechanical Engineering, Rivers State University, Port Harcourt, Nigeria. 

Abstract

Accurate characterization of non-Newtonian flow behaviour in food processing pipelines is critical for equipment design, energy optimization, and product quality control. This study investigates the rheological flow characteristics of mixed flour through a narrow industrial pipe at Dufil Prima Foods Processing Plant, Port Harcourt, Nigeria. Operational data were acquired across five process points (Pp1–Pp5) spanning feed rates of 3,000–3,425 kg/h, screw speeds of 17.5–26.5 rpm, and computed shear rates of 39,012–44,151 s⁻¹. Four established non-Newtonian rheological models—the Power-Law, Herschel-Bulkley (HB), Hallbom and Klein (HK), and Casson models—were calibrated to the experimental dataset and compared using the Absolute Average Percentage Error (AAPE) and standard deviation metrics. Mixed flour exhibited pronounced shear-thinning behaviour (flow behaviour index n = 0.33) with a yield stress of 100 Pa. Shear rate prediction followed Poiseuille’s law through a pipe of diameter 1.905 cm and length-to-diameter ratio of 25:1. The HB model demonstrated the highest predictive accuracy, achieving an AAPE of 0.12% and a standard deviation of 5.53, followed by the HK model (AAPE = 2.8%), Power-Law (AAPE = 8.78%), and Casson model (AAPE = 12.26%). The Power-Law model proved inadequate owing to its inability to capture yield stress behaviour. These findings provide quantitative rheological parameters essential for optimised pipe sizing, pump selection, and energy-efficient process design in the cereal extrusion industry.    

Keywords: Food rheology, Herschel-Bulkley model, Mixed flour, Non-Newtonian flow, Pipe flow, Shear-thinning, Yield stress

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