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Same but different - Scale up and numbering up in electrobiotechnology and photobiotechnology
摘要： Facing energy problems, there is a strong demand for new technologies dealing with the replacement of fossil fuels. The emerging fields of biotechnology, photobiotechnology and electrobiotechnology, offer solutions for the production of fuels, energy or chemicals using renewable energy sources (light or electrical current e.g. produced by wind or solar power) or organic (waste) substrates. From an engineering point of view both technologies have analogies and some similar challenges, since both light and electron transfer are primarily surface-dependent. In contrast to that, bioproduction processes are typically volume-dependent. To allow large scale and industrially relevant applications of photobiotechnology and electrobiotechnology, this opinion first gives an overview over the current scales reached in these areas. We then try to point out the challenges and possible methods for the scale up or numbering up of the reactors used. It is shown that the field of photobiotechnology is by now much more advanced than electrobiotechnology and has achieved industrial applications in some cases. We argue that transferring knowledge from photobiotechnology to electrobiotechnology can speed up the development of the emerging field of electrobiotechnology. We believe that a combination of scale up and numbering up, as it has been shown for several photobiotechnological reactors, may well lead to industrially relevant scales in electrobiotechnological processes allowing an industrial application of the technology in near future.
关键词： numbering up,photobiotechnology,reactor design,scale up,Electrobiotechnology
更新于2025-09-09 09:28:46
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Geometry Defeaturing Effects in CFD Model-Based Assessment of an Open-Channel-Type UV Wastewater Disinfection System
摘要： Computational ?uid dynamics (CFD) is a popular tool in the water industry for assessing ultraviolet (UV) reactor performance. However, due to the size of open-channel-type UV reactor systems, the CFD model requires signi?cant computational time. Thus, most evaluations have been conducted using very simpli?ed models. In order to ensure the reliability of this simpli?ed CFD model, precise numerical modeling and validation by measurements are necessary considering the geometry defeaturing level. Therefore, simpli?ed geometries in four defeatured levels were prepared for the CFD model, and simulations were performed to determine the level of geometric simplicity required to derive reliable results. A bioassay test was also conducted for a pilot-scale open-channel-type UV reactor that has the same geometrical con?guration as the CFD model. Good agreement was observed between the bioassay test and CFD model results. It was found that the reduction equivalent dose (RED) is not signi?cantly affected by geometry defeaturing under the assumption that the inlet ?ow conditions are relatively uniform. In multiple bank operation, the addition of banks yields a linear increment of the RED in the CFD model, however, a lower RED than the measured value was presented, especially for serial bank addition. The related aspects of the detailed ?ow physics and disinfection characteristics were also presented. These results are expected to provide useful information for CFD modeling, reactor design, and the assessment of the open-channel-type UV reactors.
关键词： geometry defeaturing,reduction equivalent dose,UV disinfection,computational ?uid dynamics,open-channel-type UV reactor,multiple bank operation
更新于2025-09-09 09:28:46
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Experimental framework for evaluation of the thermodynamic and kinetic parameters of metal-oxides for solar thermochemical fuel production
摘要： The two-step metal oxide redox cycle is a promising and thermodynamically attractive means of solar fuel production. In this work, we describe the development of a high-temperature tubular reactor in which the fundamental thermodynamic and kinetic behaviour of thermochemical materials can be readily assessed. This reactor system is capable of operating at temperatures up to 1873 K, total pressures ranging from vacuum to ambient, and oxygen partial pressures (pO2) as low as 10-29 atm. Compared to off-the-shelf systems like thermogravimetric analyzers (TGA) or indirect conductivity-based measurement systems, this system has three inherent benefits: (1) the flexibility to control the sample morphology (e.g. powder, packed bed, reticulated porous ceramic, or pellet), (2) the potential for a well-developed and characterized flow, and (3) the ability to readily customize the system on demand (e.g. easy integration with a steam generator to control and operate at very low pO2). The reactor system and experimental methods were validated by performing isothermal relaxation experiments with undoped ceria, wherein the sample environment was rapidly altered by stepwise changes in the delivered H2O vapor concentration, and comparing measured oxygen nonstoichiometries with accepted data available in the literature. Data was measured at temperatures from 1173-1473 K and pO2 from 4.54×10-18-1.02×10-9 atm. The measured equilibrium data displayed strong agreement with the literature and the expected trends were preserved. Kinetic data was extracted by first transforming reactant concentrations measured downstream of the reaction zone using a tanks-in-series mixing model to account for gas dispersion. Next, a mechanistic kinetic model distinguishing surface and bulk species concentrations was fit to the data to extract pertinent thermodynamic and kinetic parameters. The model assumed a two-step reaction mechanism mediated by the formation of an intermediate hydroxyl species on the surface. Activation energies and defect formation enthalpies and entropies for the forward and reverse reactions were found to be in good agreement with previous modelling efforts, providing further validation of the use of this system to explore thermodynamic and kinetic behaviour of emerging thermochemical materials.
关键词： thermodynamic and kinetic parameters,undoped ceria,solar fuel production,metal oxide redox cycle,high-temperature tubular reactor
更新于2025-09-09 09:28:46
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Towards a new image processing system at Wendelstein 7-X: From spatial calibration to characterization of thermal events
摘要： Wendelstein 7-X (W7-X) is the most advanced fusion experiment in the stellarator line and is aimed at proving that the stellarator concept is suitable for a fusion reactor. One of the most important issues for fusion reactors is the monitoring of plasma facing components when exposed to very high heat loads, through the use of visible and infrared (IR) cameras. In this paper, a new image processing system for the analysis of the strike lines on the inboard limiters from the first W7-X experimental campaign is presented. This system builds a model of the IR cameras through the use of spatial calibration techniques, helping to characterize the strike lines by using the information given by real spatial coordinates of each pixel. The characterization of the strike lines is made in terms of position, size, and shape, after projecting the camera image in a 2D grid which tries to preserve the curvilinear surface distances between points. The description of the strike-line shape is made by means of the Fourier Descriptors.
关键词： fusion reactor,infrared cameras,Fourier Descriptors,stellarator,Wendelstein 7-X,strike lines,image processing,spatial calibration
更新于2025-09-09 09:28:46
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[ASME 2018 26th International Conference on Nuclear Engineering - London, England (Sunday 22 July 2018)] Volume 9: Student Paper Competition - Modelling of X-Ray Radioscopy for Phase Topology Estimation During Corium Sodium Interaction
摘要： In case of a severe accident scenario in a Sodium cooled Fast Reactor (SFR) such as the ASTRID demonstrator, the fuel might melt and interact with the coolant i.e. liquid sodium. This molten Fuel Coolant Interaction (FCI) can generate an energetic vapor explosion that can jeopardize the reactor structures. The yield of the vapor explosion is strongly dependent on the local distribution of the fragmented melt with respect to the local vapor fractions. The medium is composed of three phases, i.e. corium, liquid sodium and vapor sodium. Thus, a study of the three phase distribution within the system is a key to understand the extent of the explosion. PLINIUS-2, the future large mass experimental platform of CEA Cadarache will be dedicated to conducting experiments to understand the behavior of prototypic corium in case of severe accidents. In order to study these interactions, a high energy X-ray imaging system is being developed. This system consists of a 15 MeV Linear accelerator producing high energy X-rays with significantly high flux, which are attenuated as it passes through the highly dense test section. The transmitted radiation is detected and re-emitted as visible light by the GADOX screen coupled to the CMOS camera. Using this system to study the interaction between corium and sodium is particularly challenging due to the small corium particulates of the size of the order of 1 mm. The qualification of the foreseen radioscopy system on the visualization of such an interaction requires the development of physical phantoms. This paper presents the preliminary simulations of expected images of corium fragments in sodium, vapor bubbles and vapor film around the fragments. The simulations are carried out using a CEA Cadarache in-house tool MODHERATO, which produces radiographic images in satisfactory agreement with the real time imaging. The simulation of particles is based on the knowledge of interaction phenomenology gained from past experiments and on the statistical analysis of the size of corium particles formed. The models which, according to MODHERATO results, qualify to be detected and resolved, help manufacturing physical phantoms to conduct the experiments.
关键词： Sodium cooled Fast Reactor,Fuel Coolant Interaction,corium-sodium interaction,MODHERATO,X-ray imaging
更新于2025-09-09 09:28:46
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[Advances in Chemical Engineering] Spatially Resolved Operando Measurements in Heterogeneous Catalytic Reactors Volume 50 || Spatio-Temporal Phenomena in Monolithic Reactors Measured by Combined Spatially-Resolved Mass Spectrometry and Optical Frequency Domain Reflectometry
摘要： Measuring the spatiotemporal temperature and reacting species concentrations of a reacting system under realistic conditions is essential to optimize the reactor design and operation. Conventional measurements of the inlet and outlet values provide only a partial picture of the reactor behavior. We describe the novel method coherent optical frequency domain reflectometry (c-OFDR) which provides unparalleled information about the spatiotemporal temperature in a catalytic reactor. c-OFDR launches a laser beam through an optical fiber positioned inside a reactor. The spatial dependence of temperature is determined through the measured spectral shift of reflected scattering light frequency. The advantages of c-OFDR include high spatial and temporal resolution (3 mm and 0.9 Hz), broad operating range (up to 800°C), noninvasive measurement (125 μm OD), stationary, and chemically resistant (gold-coated) sensor. In addition to describing the theory and standard operation of c-OFDR, we demonstrate c-OFDR for several applications involving reaction in a catalytic monolith during both steady-state and transient operation. The combination of c-OFDR with spatially resolved capillary inlet mass spectrometry (SpaciMS) provides detailed characterization of a catalytic reactor under periodic operation. Combined SpaciMS and c-OFDR successfully follow the cyclic lean/rich behavior during temperature programmed oxidation experiments. SpaciMS invasiveness is assessed through systematic measurement of the temperature by c-OFDR and concentration by SpaciMS. In an ideal adiabatic reactor, the temperature peak and complete reactant conversion should occur at the same position. Our experiments enabled generation of a map of operating conditions under which this did not occur which helps identify when the SpaciMS method is invasive.
关键词： reactor design,SpaciMS,catalytic reactor,spatiotemporal temperature,coherent optical frequency domain reflectometry
更新于2025-09-04 15:30:14
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Removal of Hg <sup>0</sup> from Simulated Flue Gas by Ultraviolet Light/Heat/Persulfate Process in an UV-Impinging Stream Reactor
摘要： Removal of Hg0 from simulated flue gas by ultraviolet light (UV)/heat/ammonium persulfate process in an UV-impinging stream reactor was investigated for the first time. Experiments were conducted to evaluate the effects of several parameters and gas composition on Hg0 removal. Mechanism and kinetics of Hg0 removal were also investigated. The results indicated that Hg0 removal efficiency was increased by increasing UV radiation intensity, activation temperature, persulfate concentration, and solution circulation rate; was decreased by increasing solution pH and SO2 concentration; and was not obviously affected by Hg0 and NO concentrations. Hg0 was oxidized by four pathways: (A) oxidized by SO4?(cid:129) and (cid:129)OH that were produced from UV-light activation of S2O82?. In the four pathways, the “A” pathway plays a major role in the removal of Hg0, and the other pathways “B?D” only play a complementary role. When CS2O82? < 0.06 mol/L or UV radiation intensity < 78 μW/cm2, the Hg0 removal process belongs to a moderate speed reaction. Hg0 removal can be enhanced by simultaneously increasing the mass transfer rate and chemical reaction rate. When CS2O82? ≥ 0.06 mol/L and UV radiation intensity ≥ 78 μW/cm2, the Hg0 removal process belongs to a fast reaction. Hg0 removal can be further enhanced by improving mass transfer rate (e.g., increasing gas?liquid contact area and enhancing turbulence in reactor).
关键词： UV-impinging stream reactor,mechanism,kinetics,Hg0 removal,UV/heat/persulfate process
更新于2025-09-04 15:30:14
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Silicon Film Deposition Using a Gas-Jet Plasma-Chemical Method: Experiment and Gas-Dynamic Simulation
摘要： This paper presents the results of an experimental study, numerical calculation, and analysis within the framework of a gas-dynamic model of silicon ?lm deposition by a gas-jet plasma-chemical method. A numerical model of gas mixtures ?owing out of an annular nozzle unit and into a reactor is developed, and it allows one to determine a ?lm thickness distribution over the surface of substrates placed in the reactor and satisfactorily describes the experimental data obtained.
关键词： reactor,simulation,plasma-chemical deposition,thin silicon ?lms,free jet,electron-beam plasma,DSMC method
更新于2025-09-04 15:30:14
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Polydopamine‐coated poly(vinylidene fluoride) membranes with high ultraviolet resistance and antifouling properties for a photocatalytic membrane reactor
摘要： We modi?ed poly(vinylidene ?uoride) (PVDF) membranes with a polydopamine (PDA) coating for photocatalytic membrane reactor application with appropriate UV resistance and studied the effects of the PDA coating conditions (i.e., coating time and dopamine concentration) and UV irradiation time on the modi?ed PVDF membrane properties. The PVDF membrane that was surface-coated with the appropriate dopamine solution concentration and coating time played a key role in controlling the membrane properties and in protecting the modi?ed membrane against UV radiation. The optimization of the coating condition not only completely protected the modi?ed membrane from free-radical attack initiated through UV irradiation but also improved the membrane hydrophilicity, antifouling properties, ?ltration performance, and mechanical strength of the membrane. UV irradiation of the membrane that was surface-coated with a high-concentration dopamine solution for a long coating time resulted in a higher mechanical strength than that of the membrane without the application of UV irradiation.
关键词： free radical scavenger,photocatalytic membrane reactor,polydopamine,UV-resistance
更新于2025-09-04 15:30:14