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The Turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T) is a moist-air closed-loop wind tunnel which provides a perfect platform for small scale studies on entrainment. It comprises two air streams that are conditioned and controlled separately in terms of temperature, humidity and flow speed. Turbulence is induced by a passive grid above the line where the two air streams mix. For this study, a droplet generator is installed into the wind tunnel to provide cloud droplets. These are fed directly into the mixing zone. The two air streams are conditioned to mimic in-cloud and out-of-cloud conditions. The flow speed in one of the streams is varied to create different shear flows in order to test its impact on the droplet size distribution. The measurements are accompanied by CFD simulations which are verified by the point measurements in the wind tunnel and allow to retrieve full 3D fields.This presentation will show results from the experiments and subsequent modelling, and discuss future plans using this data. Snapshots of the CFD simulations show the variation of the droplet stream which in higher shear conditions shows signs of patchiness and breaking up. This translates into lower cloud particle number concentrations in the averaged observational data. Interestingly, the observations indicate the growth of droplets, which is probably a result of collision and coalescence. Furthermore, the role of different mixing regimes will be discussed, particularly when looking at the shift in mean sizes of the cloud droplets in different shear environments., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

In a previous work by our group, pulsed electric field (PEF) pretreatment has been proposed as a promising technique for the extraction of high valued amino acids concentrates from microalgae S. almeriensis, and the following hydrothermal liquefaction (HTL) of residual biomass produces better quality biocrude with higher yield. However, to which extent could PEF-HTL combined technique enhance the microalgae biofuel economically is still unclear. Herein, we report a preliminary techno-economic assessment of PEF-HTL process within a microalgae biorefinery plant with an output of 0.5 MW in the form of biocrude. Results indicate that production of microalgae biofuel alone is still far from commercial application, leading to an annual loss of 2.615 M€. While a fractionation step to extract high-value products promises to reduce the overall capital costs significantly, PEF treatment could improve this effect bringing the by-produced microalgae biofuel to a competitive level (0.78 €·kg-1). The market price for high-value product plays an essential role in the final costs. Given that selling microalgae biofuel should occur at the same price of the crude oil (0.37 €·kg-1), the value added amino-acid based product minimum price is supposed to be 7.43 €·L-1 for a positive capital return., Proceedings of the 28th European Biomass Conference and Exhibition, 6-9 July 2020, Virtual, pp. 526-529

Extraction of high value product from microalgae and utilization of the residual biomass for biofuel production promise to bring economical benefits for a microalgae biorefinery. Recently, pulsed electric field (PEF) treatment has gained much attention to easier facilitate the extraction of valuables from microalgae. For conversion of microalgae biomass and residues, hydrothermal liquefaction (HTL) is considered as a suitable post-method. In this study, fresh microalgae Scenedesmus almeriensis was treated by PEF and then subjected to extraction of amino acids after enzymatic protein hydrolysis. The residual biomass obtained from PEF treated and PEF-assisted valuables extraction were subjected to HTL in micro-autoclaves at a temperature of 350°C, pressure of 25 MPa for 15 min holding time. Product yields and analytical results obtained by elemental content, fourier-transform infrared spectroscopy, and gel permeation chromatography show that PEF alone has no significant direct influence on microalgae HTL. However, PEF accelerates the formation of amino acids by enzymatic hydrolysis, improving the extraction efficiency up to 150 % in the first 60 min of the extraction, while this accelerating effect fades out with longer extraction time. The extracted residue promises to produce 6 wt.% higher biocrude yield and better quality biocrude with lower nitrogen., Proceedings of the 27th European Biomass Conference and Exhibition, 27-30 May 2019, Lisbon, Portugal, pp. 1127-1131

The Department for Pulsed Power Technology is focusing on research and development of pulsed power technologies and related applications. The applications involves the electroporation of biological cells for extraction of cell contents (PEF- process), dewatering and drying of green biomass, pre-treatment of micro algae for energetic use and sustainable reduction of bacteria in contaminated effluents. Another key research topic is devoted to the development of corrosion barriers and materials for improved compatibility of structural materials in contact with liquid metal coolants. This year's report focuses primarily on the activities and results of ongoing third-party funded projects of the department.