Nonuniform Triangular Screw Geometry Enables Distributed Pressure Generation and Improves Process Performance in Industrial Single-Screw Pet Food Extrusion

Flores F.C.; Vera C.W.L.; Echegaray L.A.R. · Journal of Food Process Engineering (2026) · DOI: 10.1111/jfpe.70748

Resumen

This study evaluates a nonuniform triangular screw geometry for pressure distribution and process performance in an industrial single-screw pet food extruder. Periodic nonuniform channel-area reductions are hypothesized to induce localized pressure gradients that accumulate axially, enabling distributed pressure generation. Twelve triangular Chronit T-500 segments replaced the conventional double-flight mixing screw, eliminating the need for an external back-pressure valve (BPV). Validation used 1936 records from 6 months of continuous production, analyzed with a quasi-experimental sequential design. Versus BPV, the triangular screw increased capacity 5.8% (d = 1.48), reduced die pressure 53.6% (d = −6.70), increased specific mechanical energy 4.5% (d = 1.53), and reduced deviation from target bulk density 51%. Variability decreased in five of six indicators. Welch's ANOVA with 95% confidence intervals was used; the effect persisted at production-lot level. Results are consistent with progressive pressure accumulation through geometrically induced flow restriction, positioning screw geometry as a primary design variable.

Instituciones: Universidad Tecnológica del Perú