Showing papers on "Packed bed published in 2013"
TL;DR: In this paper, the authors describe and analyze the efficiency of a new solar-thermochemical reactor concept, which employs a moving packed bed of reactive particles produce of H2 or CO from solar energy and H2O or CO2.
Abstract: We describe and analyze the efficiency of a new solar-thermochemical reactor concept, which employs a moving packed bed of reactive particles produce of H2 or CO from solar energy and H2O or CO2. The packed bed reactor incorporates several features essential to achieving high efficiency: spatial separation of pressures, temperature, and reaction products in the reactor; solid–solid sensible heat recovery between reaction steps; continuous on-sun operation; and direct solar illumination of the working material. Our efficiency analysis includes material thermodynamics and a detailed accounting of energy losses, and demonstrates that vacuum pumping, made possible by the innovative pressure separation approach in our reactor, has a decisive efficiency advantage over inert gas sweeping. We show that in a fully developed system, using CeO2 as a reactive material, the conversion efficiency of solar energy into H2 and CO at the design point can exceed 30%. The reactor operational flexibility makes it suitable for a wide range of operating conditions, allowing for high efficiency on an annual average basis. The mixture of H2 and CO, known as synthesis gas, is not only usable as a fuel but is also a universal starting point for the production of synthetic fuels compatible with the existing energy infrastructure. This would make it possible to replace petroleum derivatives used in transportation in the U.S., by using less than 0.7% of the U.S. land area, a roughly two orders of magnitude improvement over mature biofuel approaches. In addition, the packed bed reactor design is flexible and can be adapted to new, better performing reactive materials.
209 citations
TL;DR: In this paper, the effect of porosity on the internal fluid flow and quantify the drag force on particles in packed beds is studied by a parallel lattice Boltzmann (LB) model.
198 citations
TL;DR: In this paper, the Ergun equation was used to predict the pressure drop over a packed bed of irregular particles such as crushed rock with any degree of accuracy, an empirical equation must be obtained from a sample of the particles for a given packing arrangement.
171 citations
TL;DR: In this article, an upflow anaerobic packed bed reactor configuration to produce hydrogen using cheese whey as the substrate was tested, and the microbiological composition was linked to the reactor operation.
164 citations
TL;DR: In this article, an experimental study was conducted to evaluate the thermal performance of a new solar air heater collector using a packed bed of spherical capsules with a latent heat storage system, using both first and second law of thermodynamics, the energetic and exegetic daily efficiencies were calculated in closed/opened and opened cycle mode.
126 citations
TL;DR: In this article, a transient two-dimensional dispersion-concentric (D-C) model for heat transfer and fluid dynamics in a packed-bed molten salt thermocline thermal storage system is presented.
108 citations
TL;DR: In this paper, a robust system-scale heat transfer model for the packed bed was developed and accounts for wall heat transfer and intra-particle diffusion effects, based upon the temperature field modeling, recovered and lost exergy were calculated.
104 citations
TL;DR: In this article, a packed bed is used for testing the combination of NTP and pellet type catalysts, which can be used for surface treatment of honeycomb catalysts by NTP.
100 citations
TL;DR: In this paper, a fixed-bed Fenton-like reaction with activated carbon impregnated with iron (AC/Fe) was used for the treatment of textile effluents.
96 citations
TL;DR: The HSPBD reactor was found to display remarkably better benzene degradation, mineralization, and energy performance than surface or packed-bed discharge reactors alone and the addition of O2 to N2 allows for efficient degradation of benzene.
Abstract: An innovative plasma reactor, which generates hybrid surface/packed-bed discharge (HSPBD) plasmas, was employed for the degradation of benzene. The HSPBD reactor was found to display remarkably bet...
88 citations
TL;DR: In this article, a two-dimensional computational framework of rotating packed bed (RPB) was developed to investigate the liquid phase flow within RPB numerically, and the volume of fluid multiphase model, sliding model and Reynolds stress model were used to compute the velocity fields and to capture the interface between gas-liquid phases in RPB.
TL;DR: In this article, the authors developed and integrated particle-particle and particle-wall heat transfer models into their in-house unsteady three-dimensional discrete element method (DEM) software.
TL;DR: In this paper, the application of chemical looping combustion (CLC) in pressurized packed bed reactors using syngas as a fuel is discussed, and a novel reactor configuration is introduced in which the desired temperature rise for obtained hot pressured air suitable for a gas turbine is obtained by carrying out the process with two packed bed reactor in series.
TL;DR: The cheese whey conversion process was characterized in terms of metabolites production, lactose conversion and biofilm mass, and butanol selectivity of the overall solvents production 82 wt%.
TL;DR: In this article, the pyrolytic behavior of a cylindrical packed bed of beech wood pellets, uniformly heated along the lateral surface, is studied, and the trends shown by the mass loss rate and the yields of the lumped product classes are in agreement with previous literature.
Abstract: The pyrolytic behavior of a cylindrical packed bed of beech wood pellets, uniformly heated along the lateral surface, is studied. As the heating conditions are varied, the trends shown by the mass loss rate and the yields of the lumped product classes are in agreement with previous literature. Moreover, detailed measurements of the thermal field permit, for the first time, the observation at the central core of the bed, of sequential (a) exothermic, (b) endothermic, and (c) exothermic effects. The examination of the corresponding temperature ranges indicates that they are linked, in the order, to the (primary and secondary) degradation of (a) hemicellulose, (b) cellulose and lignin, and (c) lignin. The dependence on the heating conditions is also explained of the center temperature overshoot (with respect to the steady value) which attains maximum values around 90 K.
TL;DR: In this paper, a rigorous rate-based model for CO2 absorption using aqueous ammonia in a packed column has been developed and used to simulate results from a recent pilot plant trial of an ammonia-based post-combustion capture process at the Munmorah Power Station, New South Wales, Australia.
TL;DR: In this article, two mathematical models including rate-based and equilibrium-stage were applied and compared for CO2 absorption by 2-amino-2-methyl-1-propanol (AMP) solution in a packed column.
TL;DR: Electrocoagulation of textile wastewater using a uniquely designed reactor was very effective and direct dischargeable effluent, complying with legal requirements, was obtained and maghemite is the main by-product formed after EC.
TL;DR: In this article, the effect of various experimental parameters on the rate of zinc ion removal, such as initial zinc ion concentration, packed bed rotation speed and temperature, was investigated in a rotating cylindrical basket reactor.
Abstract: The present study is concerned with the mass transfer and kinetics study of zinc ions removal from aqueous solution using a cation exchange resin packed in a rotating cylindrical basket reactor. The effect of various experimental parameters on the rate of zinc ion removal, such as initial zinc ion concentration, packed bed rotation speed and temperature has been investigated. In addition to find a suitable equilibrium isotherm and kinetic model for the zinc ion removal in a batch reactor. The experimental isotherm data were analyzed using the Langmuir, Freundlich and D–R equations. The equilibrium data fit well in the Langmuir isotherm. The experimental data were analyzed using four sorption kinetic models, pseudo-first and second-order equations, the Elovich and the intraparticle diffusion model equation, to determine the best fit equation for the biosorption of zinc ions onto purolite C-100 MH resin. Results show that the Elovich equation provides the best correlation for the biosorption process.
TL;DR: In this paper, phase change material (PCM) is used in order to enhance the energy density and the stratification of the water tank, and the experimental set up consists mainly of a cylindrical storage tank with a capacity of 3.73 L filled with spherically encapsulated PCM.
TL;DR: In this article, the authors developed closure laws that can be implemented in CFD codes for Mellapak 250.X packing via gamma-ray tomography measurements, which can be used to predict liquid dispersion.
TL;DR: In this paper, a Pd-based packed bed membrane (PBMR) was used for methanol steam reforming (MSR) reaction and developed a valid model that can provide a tool for deeper analyses of reaction parameters in the PBMR.
TL;DR: In this article, a wire mesh packed double-pass solar air heaters with attaching wire mesh under external recycle was investigated experimentally and theoretically, and the improvement of device performance was represented graphically and compared.
TL;DR: Different configurations for an adequate heat management in dynamically operated packed bed reactors for chemical looping combustion (CLC) have been investigated and compared using syngas from a coal gasification unit as fuel as mentioned in this paper.
01 Jan 2013
TL;DR: Packed bed AFEX shows significant promise as a biomass pretreatment for use at distributed depots and gives enzyme hydrolysis yields equal to biomass treated in stirred batch reactors, and formed durable pellets.
Abstract: Background: Pretreatment of biomass at regional depots could simplify supply logistics for the emerging biofuels industry. Ammonia Fiber Expansion (AFEX™) could be an appropriate pretreatment method for use at depots, if the process can be simplified. Here we investigate pretreatment of corn stover and wheat straw using a simple packed bed AFEX system that exploits the high porosity of biomass to facilitate ammonia transport. Results & discussion: Steam stripping vertical packed beds allowed recovery of more than 90% residual ammonia as substantially dry vapor. AFEX-treated biomass gave enzyme hydrolysis yields equal to biomass treated in stirred batch reactors, and formed durable pellets. Conclusion: Packed bed AFEX shows significant promise as a biomass pretreatment for use at distributed depots.
TL;DR: In this paper, the storage behavior of a fluidized bed filled with a granular phase change material (PCM) with a small particle diameter ( d p ¯ = 0.54 mm ) was compared to that of well-known storage methods such as fluidized beds with sand and packed beds based of sand and PCM.
TL;DR: In this paper, a new numerical approach is proposed to calculate the radiation heat transfer in such a bed from its structure using the Voronoi network model, which is used to investigate the effects of variables such as particle thermal conductivity, emissivity and size, and bed temperature as well.
Abstract: Radiation represents an important contribution to the heat transfer through a packed bed. The packing structure is important in the determination of the radiation heat transfer, but this aspect is not explicit in most of the mathematical models proposed in the literature. Here, a new numerical approach is proposed to calculate the radiation heat transfer in such a bed from its structure using the Voronoi network model. On this basis, the effective thermal conductivity (ETC) is evaluated by taking into account the effects of the radiation heat transfer and conduction through neighbor particles and stagnant fluid. The validity of this approach is verified by comparing the calculated and measured ETCs under different conditions. This approach is used to investigate the effects of variables such as particle thermal conductivity, emissivity and size, and bed temperature as well. The relative contributions of different heat transfer mechanisms are analyzed. It is shown that there is a similarity in the probabil...
TL;DR: In this paper, the removal of oil from oil-in-water (o/w) emulsion was investigated using a packed bed of an ion-exchange resin (Purolite OL 100) beads.
TL;DR: In this article, the authors compared and validated two different mathematical models of packed bed storage with PCM, more specifically the heat transfer during charge of the PCM capsules, and concluded that free convection is not as important as forced convection in the studied case.
TL;DR: In this article, the Fischer-Tropsch synthesis (FTS) was evaluated on a 30-wt.% Co catalyst promoted with 0.1 -1 ¼ Ru supported on a silicon carbide (SiC) foam in a platelet structured milli-reactor (PSR).