CFD-based design and optimization of a mixing impeller for enhanced viscosity and pH measurements in hand dish-washing liquid products

Research and development of hand dish washing (HDW ) liquid products aims at ensuring optimal cleaning performances, with a focus on parameters such as pH and viscosity. HDW products are handcrafted manually by the lab personnel, resulting in a most time-consuming and repetitive task. To tackle this problem, a new manufacturing process named Flex Make Lite was put in place. Flex Make Lite consists of a series of operational units designed to manufacture hand dish washing liquid products with reduced time and increased accuracy compared to the standard lab procedure. While this improved process is promising, it has some limitations regarding the types of products that can be processed. A major issue is related to the impeller type installed in the last operational unit named Trimming Unit, where the viscosity and the pH are adjusted by injecting trimming agents inside the HDW product. The anchor impeller installed in the Trimming Unit is responsible for inaccurate viscosity measurements, high shear rate, and inefficient mixing. As a consequence, only HDW products with a viscosity between 300 cP and 2000 cP can be processed in the Trimming Unit. This thesis focuses on improving the capability of the Flex Make Lite process by proposing an alternative impeller design to the anchor impeller. The methodology involves the design and optimization of various impeller shapes and geometrical parameters using computational fluid dynamics simulation, followed by experimental validation. The novel impeller design is implemented in the Trimming Unit, and its performances are assessed. The novel impeller guarantees excellent mixing performances, accurate viscosity measurement, and generate a shear rate 37 % lower than the current impeller.