Modelling the Mixing Process of Liquids With Concentrates in Capsules

In food industry mixing of concentrates contained in capsules with liquids such as milk or water for the production of warm drinks is becoming common practice the last couple of years. This process is characterized by complicated physical phenomena: the concentrates’ viscosity is temperature dependent, the liquid is non-Newtonian and the mixing process is turbulent. The industrial objective at the end of the process is a uniform liquid end product with as little as possible left over concentrate in the capsule. The optimization of the mixing process is typically done by trial and error in laboratories, which is time consuming and expensive. Computer models can significantly reduce the manufacturing costs associated with laboratory optimization and give a better insight of the process. The objective of this paper is to create a computer simulation model that is able to capture the physical processes occurring during the production of warm drinks using finite elements. The model should be able to correctly represent the mixing of the solid concentrate with the liquid injected inside the capsule compartment. Finite element method is used to solve the flow, heat exchange and concentration problem. In the paper different shapes of the capsule and how they influence the mixing are compared and their suitability for industry according to the amount of concentrate left in the capsule at the end of the process are assessed.