Title: High-Speed Imaging of Transient Hydrogen Jets with Laser-Induced Rayleigh and Raman Scattering Techniques

Dr. Bin Wu

Postdoctoral Fellow, supervised by Prof. Gaetano Magnotti

Abstract:  To further reduce the anthropogenic emission of carbon dioxide (CO₂) in the global range, hydrogen internal combustion engine vehicles (H₂-ICEVs) have been considered a promising zero-CO₂ solution in the present and near future, particularly for heavy-duty applications. However, with the highly distinctive thermophysical properties of H₂ compared to fossil fuels, several challenges must be overcome for the realistic adaptation of traditional internal combustion engines (ICEs) burning H₂. The design of high-pressure gaseous fuel injectors, capable of providing the high flow rate of H₂ needed for engine operation at medium and high loads, is necessary because of the low volumetric energy density of H₂ by nature.

The current work demonstrates the feasibility study of quantitative measurement of transient H₂ jets using high-speed 2-D Raman and Rayleigh scattering techniques. The compressed H₂ at medium to high pressures is injected into a near-quiescent, pressurized environment of pure N₂ at room temperature. By using a powerful burst-mode laser as the light source and high-speed CMOS cameras for signal collection, the unsteady turbulent H₂ jets issued from the injector are well captured at high repetition rates up to 100 kHz for Rayleigh and 10 kHz for Raman imaging, and the mole fraction field of H₂ is obtained. Such diagnostic techniques and corresponding data can be beneficial to the ongoing design of novel H₂ injectors, as well as the validation of numerical models.

Bio:  Bin Wu is now a postdoctoral fellow working with Prof. Gaetano Magnotti at CCRC. Before joining KAUST in 2022, he obtained his Ph.D. degree from Georgia Institute of Technology, USA, focusing on the topic of ozone assisted combustion. In Prof. Magnotti’s group, Bin’s research interest is mainly in the area of advanced laser diagnostics and high-pressure oxy-fuel combustion. 

Title: Cutting off the upstream and downstream costs for CO₂ electroreduction by upcycling fermentation emissions into ethanol

Ruofan Sun 

Ph.D. student, supervised by Prof. Xu Lu

Abstract:   Electrochemical reduction of CO₂ (CO₂RR), when powered by renewables, opens up a new venue to mitigate the greenhouse gas while producing valuables sustainably. Nevertheless, this technology has been largely limited by high costs of the upstream CO₂ feed and the downstream product separation. Here we report a hybrid bio-electrochemical system, integrating yeast fermentation with CO₂RR in one single cell, that upcycles the fermentation-emitted CO₂ into ethanol. We engineer a CuO-Ag tandem electrocatalyst with rationally designed CuO-Ag interfaces that poses minimal impact on the yeast, whereas efficiently converting CO₂ into ethanol against the side reactions such as hydrogen evolution and glucose reduction. We showcase the win-win model enabled by the hybrid system – the CO₂RR cost can be cut for 22.3% because the fermentation process provides free high-purity CO₂ source and free ethanol distillation; in return, CO₂RR reduces the CO₂ emissions of fermentation and increases the final ethanol product concentration. This proof-of-concept sheds light on a tempting possibility of a cost-effective CO₂ value chain.

Bio: Ruofan Sun received her Bachelor’s degree in Southern University of Science and Technology (Sustech) in Shenzhen, China. He joined in KAUST as a student in 2018 and is now a PhD student under Prof. Xu Lu’s supervision. His research interests are electrochemical CO₂ reduction reaction (CO₂RR), hydrogen evolution reaction (HER) and techno-economic analysis (TEA) of electrolyzer.