The DLR‑AeroKinetics project, carried out from 1 November 2019 to 31 January 2023, investigated the drying behaviour of resorcinol‑formaldehyde (RF) aerogel gels and developed an analytical toolbox for kinetic studies of sol‑gel synthesis, ageing and ambient‑pressure drying. The study focused on the influence of gel layer thickness and drying temperature on mass loss, drying time and energy consumption, and identified an optimal drying temperature that balances speed and energy efficiency.

Drying experiments were performed on RF gels with layer thicknesses of 0.33 cm, 0.50 cm and 1.00 cm at 60 °C, 70 °C and 80 °C. The reference drying time for a standard 1 cm thick gel at 60 °C was 48 h (2880 min). The measured drying times decreased markedly with increasing temperature and decreasing thickness. For the 1.00 cm gel, drying times were 630 min at 60 °C, 550 min at 70 °C and 370 min at 80 °C. The 0.33 cm gel dried in 2280 min, 1500 min and 1220 min at the same temperatures, while the 0.50 cm gel required 1130 min, 900 min and 750 min. These results confirm that thinner layers and higher temperatures accelerate drying by enhancing diffusion and permeation of pore liquid and by increasing the vapor pressure gradient at the gel surface.

Energy consumption was quantified by measuring the oven’s baseline load (QG) and the total drying energy (QT). At 60 °C, the baseline load was 579.6 kJ h⁻¹ and the drying energy 239.6 kJ, yielding a specific energy requirement of 1.6 kJ g⁻¹ of evaporated pore liquid. At 70 °C, the baseline load rose to 720.0 kJ h⁻¹, the drying energy to 270.0 kJ, and the specific energy requirement to 1.7 kJ g⁻¹. At 80 °C, the baseline load increased further to 871.2 kJ h⁻¹, the drying energy to 307.1 kJ, and the specific energy requirement to 2.3 kJ g⁻¹. Thus, while 80 °C shortens drying time, it also raises the energy cost per gram of removed liquid. The data indicate that 70 °C offers the best compromise, providing a substantial reduction in drying time relative to 60 °C while keeping the specific energy requirement low.

The project established a comprehensive analytical workflow. In‑situ weighing, infrared spectroscopy, high‑performance liquid chromatography, UV/Vis spectroscopy and thermogravimetric analysis were combined to monitor sol‑gel chemistry, ageing and drying in real time. A detailed procedure for setting up the analytical laboratory, procuring equipment, and training personnel was documented. Validation experiments on the full aerogel production process confirmed the reliability of the methods and produced a workflow that can be applied to other aerogel systems and scaled up for industrial use.

Collaboration involved the German Aerospace Center (DLR) as the lead institution, with partners from Rheinische Fachhochschule Köln, Hochschule Niederrhein, Universität Bayreuth and other members of the Aerogel Cluster consortium. Scientists and technicians contributed 210 personnel hours for planning, 180 hours for infrastructure setup, and 102 hours for validation experiments. Regular DLR internal meetings and biannual cluster discussions ensured progress tracking and knowledge exchange. The COVID‑19 pandemic caused a temporary delay, leading to a cost‑neutral three‑month extension that allowed the project to complete its objectives. The developed analytical toolbox and drying optimisation findings are now available to consortium members and industry stakeholders for further research and application.