The OptiTemp project, funded under the German Federal Ministry of Education and Research (grant code 13FH012PX8) and carried out from 1 October 2019 to 31 March 2023, aimed to increase the energy efficiency of injection‑molding processes by improving heat transfer in the cooling channels of moulds. In injection moulding the mould is cooled below the polymer’s solidification temperature by circulating a cooling fluid, usually water, through embedded channels. The overall energy consumption of this cooling step is limited by the heat‑transfer coefficient between the fluid and the mould wall. By enhancing this coefficient, the project sought to reduce the energy required for cooling by 20 % to 70 % and to shorten the cooling time – and thus the cycle time – by up to 10 %. A higher heat‑transfer coefficient also enables dynamic tempering, where hot and cold fluid are alternated to improve surface quality and accelerate solidification.

The consortium combined complementary expertise. The Technical University of Cologne’s Faculty of Computer Science and Engineering, led by Prof. Dr.-Ing. Denis Anders, provided the scientific foundation in heat‑transfer theory and numerical simulation. Striko Verfahrenstechnik GmbH contributed experimental facilities for testing static mixing elements and measuring pressure losses in incompressible flows. Simcon Kunststoff supplied advanced injection‑moulding simulation tools to predict temperature fields and cycle times. Voss Automotive supplied thermodynamic and flow‑design expertise for thermoelectric heat‑exchanger concepts. The Polymer Laboratory, headed by Prof. Simone Lake, integrated the developed cooling concepts into practical mould‑design and production strategies, including the acquisition of a new dynamic‑tempering system that has been used in subsequent projects.

Key technical outcomes include the design of a novel cooling‑channel geometry that increases the local heat‑transfer coefficient by 30 % to 50 % compared with conventional channels, as confirmed by both computational fluid‑dynamic simulations and experimental measurements on a dedicated test rig. The improved geometry also reduces pressure drop by less than 5 %, keeping pumping energy low. In dynamic tempering experiments, the new system achieved a 10 % reduction in cooling time while maintaining surface gloss levels comparable to those obtained with conventional hot‑fluid tempering. The project also produced a set of validated correlations for predicting heat‑transfer performance in complex channel networks, which were incorporated into the Simcon simulation package.

The OptiTemp results were disseminated through peer‑reviewed journal articles and conference presentations, and the consortium delivered tailored research services to industry partners, demonstrating the practical applicability of the findings. The project’s outcomes support the broader “FunktioPol – the polymer solution” initiative, which seeks to integrate process‑chain research across polymer manufacturing, energy use, and environmental impact. By establishing a robust framework for optimizing cooling‑channel performance, OptiTemp has laid the groundwork for future research on sustainable mould‑design and dynamic process control, thereby contributing to the long‑term goal of reducing the specific energy demand of injection‑moulding processes.