System analysis and controller design for the electric pump of a deep-throttling rocket engine

This paper proposes a controller design for the electric pump of a deep-throttling rocket engine. The nonlinearity of the system is taken into consideration by analyzing the gap metric. Then, proportional-integral-derivative controller and gain-scheduling linear quadratic regulator are designed. Analyzing the amplitude- and phase-frequency characteristics as well as the pole-zero distribution of the system, the results show that the designed controllers can stabilize the linearized equations in incremental form at different operating points. This indicates that these two controllers are available for the original system in the whole range of working conditions and this is verified in the simulation. Meanwhile, the comparison between proportional-integral-derivative controller and gain-scheduling linear quadratic regulator is presented. It demonstrates that the proportional-integral-derivative controller is better at tracking both step and ramp signals but with worse control signals. It means that the proportional-integral-derivative controller seems less suitable for real use due to severe oscillations. Meanwhile, the parameter tuning of a proportional-integral-derivative controller depends on more extensive manual tuning. Therefore, the gain-scheduling linear quadratic regulator is preferred. Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Jan-Willem van Wingerde

One-step controllable fabrication of 3D structured self-standing Al₃Ni₂/Ni electrode through molten salt electrolysis for efficient water splitting

Exploring more efficient and low-cost electrocatalysts to replace platinum (Pt) is highly desired to promote the practical hydrogen production through water splitting. Herein, a facile and effective strategy is proposed to fabricate self-standing Al3Ni2/Ni electrode with controlled phase composition and surface morphology, which is obtained by one-step electrochemical reduction of Al3+ on commercially available nickel in eutectic NaCl-KCl melt. Different from previously reported approaches, uniform Al3Ni2 monolith catalyst can directly grow onto Ni substrate. The deposit possesses unique three-dimensional (3D) cauliflower-like morphology comprising of nano- and microparticles due to the rapid nucleation rate during molten salt electrolysis. The as-fabricated Al3Ni2/Ni electrode can be directly used as the cathode to catalyze Hydrogen evolution reaction (HER). Impressively, it exhibits remarkable HER activity comparable to commercial Pt, including a low overpotential of 83.4 mV for a current density of 10 mA cm−2, a small Tafel slope of 40.7 mV dec-1, and excellent long-term stability over 36 h of continuous HER operation in 0.5 M H2SO4 solution. The intrinsic catalytic ability of Al3Ni2 with the unique hierarchical structure of nano/microsized grains can offer multiple effects, including massive exposed active sites, enhanced charge transfer and mass transport, and fast gas releasing that synergistically contribute to improving the electrocatalytic performance of HER. This work represents a highly promising approach to the design and one-step controllable fabrication of efficient and self-standing base metal electrode for electrocatalytic hydrogen production.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Yongxiang Yan