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101.
《International Journal of Hydrogen Energy》2023,48(65):25512-25526
Actually, there are different configurations used in microbial fuel cells (MFCs) with presence or absence of an ion exchange membrane between their electrodes. Specifically, MFCs that use membranes have the objective of avoiding the diffusion of oxygen and substrate between the anodic and cathodic compartment, and to achieve a correct transfer of protons from one chamber to another. In this regard, the current study seeks to prepare and characterize new composite membranes using as precursors three types of carbonaceous materials such as bone char, coconut shell activated carbon and bituminous activated carbon and natural clay. The composite membranes of bituminous activated carbon and clay showed more promising specific conductivity (42%) than the one made with pure clay. The physicochemical properties of the membranes and their precursors were elucidated by SEM/EDX analysis, IR spectroscopy, nitrogen adsorption isotherms at 77 K and optical microscopy. Further, membranes performance was assessed using microbial fuel cells (MFCs) where the composite membranes prepared with clay-bituminous carbon reached the highest voltage values (0.95–1.02 V) in open circuits, while that reached a maximum power density of 0.699 W/m3 at a current density of 4.012 A/m3 in closed circuit. This behavior is associated with the high content of silicon and aluminum in bituminous activated carbon, which favored the proper functioning of membranes in the MFCs. Specifically, with this type of cells, energy recovery of 0.0057 kWh/m3 and 0.1322 kWh/kg chemical oxygen demand (COD) removed, which indicates an extra economic income of the order of $0.0025/kg COD. Finally, the produced power was demonstrated in prototypes to power LED and four digital clocks. This novel clay-bituminous activated carbon showed promising cost-effectiveness and sustainable energy generation, which may be suitable for wastewater treatment. 相似文献
102.
为了制备同时具有优良脱汞性能和磁分离特性的磁性活性炭(MAC),采用共沉淀法制备Fe~(3+)和Fe~(2+)的不同离子配比及不同磁质量分数的MAC,并对其进行比表面积、磁化强度、扫描电镜、X射线衍射、热失重试验等分析,得到Fe~(3+)和Fe~(2+)摩尔比为1∶1,磁质量分数为25%的MAC具备良好的磁分离特性和脱汞性能。在固定床试验台上对MAC进行脱汞性能影响试验,结果表明:γ-Fe_2O_3是MAC上主要的磁性物质,O_2和HCl的存在均能加强元素汞的氧化脱除,促进MAC对汞的吸附,且其含量越高脱汞性能越好;SO_2对MAC的脱汞效率无明显影响,接触初期在MAC表面产生竞争吸附现象,造成脱汞效率先降低后升高现象;水蒸气减弱了MAC对汞的吸附效果。 相似文献
103.
《International Journal of Hydrogen Energy》2023,48(76):29759-29770
This paper presents a mathematical model in the biofilm phase and in the gas phase that has been successfully applied to investigate various aspects of the biofiltration process. The mixtures of volatile organic compounds (VOCs) are emitted from a wide range of industries, such as chemical, petrochemical, pharmaceutical, pulp paper mills, printing and paint workshops, etc. The objective of the present study is, presence of high n-propanol loading negatively affected the toluene removal; however, n-propanol removal was not affected by the presence of toluene and was effectively removed in the biofilter despite high toluene loadings. A model for toluene and n-propanol biofiltration could predict the cross-inhibition effect of n-propanol on toluene removal. Further, we studied the effects of many physical and biological parameters on model prediction. The mathematical equations (2.12)-(2.16) which are non-linear partial differential equations are solved by using the homotopy perturbation technique. Also, we derived the semi-analytical results for toluene and n -propanol concentrations for saturated and unsaturated kinetics. It is verified that the proposed solution is validated by comparing it with numerical solutions. 相似文献
104.
《International Journal of Hydrogen Energy》2023,48(74):28758-28768
Defect engineering is an effective method to tune electronic states, which can provide active sites for electrocatalytic reactions. Herein, a highly efficient sulfur-doped bimetallic hydroxyl oxide (FeCo/Vc-S) has been synthesized by a two-step hydrothermal reaction, which has the rich defective and amorphous phases. The low coordination number of Co in X-ray absorption fine structure (XAFS) analysis further confirms the Co center is the active center, while Fe plays a role in optimizing the electronic structure of active Co species. Meanwhile, abundant oxygen vacancies and metal defects are also found in the material, which greatly enhances the adsorption and desorption efficiency of × OOH. Moreover, density functional theory (DFT) shows that the addition of S atom alters the electron distribution of adjacent metal atoms, thus adjusting the electron distribution of the metal active site. These positive factors endow FeCo/Vc-S with excellent OER electrocatalytic performance, with an overpotential of only 255 mV and Tafel slope is 64.3 mV·dec−1 at a current density of 10 mA cm−2. This study provides a new route for the synthesis of bimetallic hydroxyl oxides, and also provides theoretical design for the identification of active centers and defection-rich catalysts. 相似文献
105.
Although one of the key characteristics of High Performance Computing (HPC) infrastructures are their fast interconnecting networks, the increasingly large computational capacity of HPC nodes and the subsequent growth of data exchanges between them constitute a potential performance bottleneck. To achieve high performance in parallel executions despite network limitations, application developers require tools to measure their codes’ network utilization and to correlate the network’s communication capacity with the performance of their applications.This paper presents a new methodology to measure and understand network behavior. The approach is based in two different techniques that inject extra network communication. The first technique aims to measure the fraction of the network that is utilized by a software component (an application or an individual task) to determine the existence and severity of network contention. The second injects large amounts of network traffic to study how applications behave on less capable or fully utilized networks. The measurements obtained by these techniques are combined to predict the performance slowdown suffered by a particular software component when it shares the network with others. Predictions are obtained by considering several training sets that use raw data from the two measurement techniques. The sensitivity of the training set size is evaluated by considering 12 different scenarios. Our results find the optimum training set size to be around 200 training points. When optimal data sets are used, the proposed methodology provides predictions with an average error of 9.6% considering 36 scenarios. 相似文献
106.
《Fire Safety Journal》1997,28(3):253-287
An algorithm and associated FORTRAN 77 subroutine, called VENTCF2, for calculating the effects on two-layer compartment fire environments of the quasi-steady flow through a circular, shallow (i.e. small ratio of depth-to-diameter), horizontal vent connecting two spaces is presented. The two spaces can be either two inside rooms of a multi-room facility or one inside room and the outside ambient environment local to the vent. The flow is determined by consideration of standard orifice-type flows driven by cross-vent pressure differences and, when appropriate, the combined pressure- and buoyancy-driven flows which occur when the density configuration across the vent is unstable, i.e. a relatively cool, dense gas in the upper space overlays a less dense gas in the lower space. The algorithm calculates rates of flow exchange between the two spaces based on previously reported model equations. Characteristics of geometry and the instantaneous environments of the two spaces are assumed to be known and specified as inputs. Outputs calculated are the rates and properties of the vent flow at the elevation of the vent as it enters the top space from the bottom space and/or as it enters the bottom space from the top space. Rates of mass, enthalpy and products of combustion extracted by the vent flows from upper and lower layers of inside room environments and from outside ambient spaces are determined explicitly. VENTCF2 is an advanced version of the algorithm /subroutine VENTCF in that it includes an improved theoretical and experimental basis. The subroutine is completely modular and it is suitable for general use in two-layer, multi-room, zone-type fire model computer codes. It has been tested numerically over a wide range of input variables and the results of some of these tests are described. 相似文献
107.
M. B. Koss J. C. LaCombe L. A. Tennenhouse M. E. Glicksman E. A. Winsa 《Metallurgical and Materials Transactions A》1999,30(12):3177-3190
Dendritic growth is the common mode of solidification encountered when metals and alloys freeze under low thermal gradients.
The growth of dendrites in pure melts depends on the transport of latent heat from the moving crystal-melt interface and the
influence of weaker effects like the interfacial energy. Experimental data for critical tests of dendritic growth theories
remained limited because dendritic growth can be complicated by convection. The Isothermal Dendritic Growth Experiment (IDGE)
was developed specifically to test dendritic growth theories by performing measurements with succinonitrile (SCN) in microgravity,
thus eliminating buoyancy-induced convection. The first flight of the IDGE in 1994 operated for 9 days at a mean quasi-static
acceleration of 0.7 × 10−6
g
0. The velocity and radius data show that at supercoolings above approximately 0.4 K, dendritic growth in SCN under microgravity
conditions is diffusion limited. By contrast, under terrestrial conditions, dendritic growth of SCN is dominated by convection
for supercoolings below 1.7 K. The theoretical and experimental Peclet numbers exhibit modest disagreement, indicating that
transport theories of dendritic solidification required some modification. Finally, the kinetic selection role for dendritic
growth, VR
2=constant, where V is the velocity of the tip and R is the radius of curvature at the tip, appears to be independent of the gravity environment, with a slight dependence on
the supercooling. 相似文献
108.
《Combustion and Flame》2006,144(1-2):249-260
A model of species and particulate formation in laminar diffusion flames is presented. The kinetic model is based on the chemistry of fuel oxidation and pyrolysis, the formation of aromatics and their growth into particle nuclei, particle growth by surface reactions, coagulation, and finally particle oxidation. A sectional model is used for the particle phase. The sectional method divides the particle mass range into classes of species each with a rate equation for surface growth, coagulation, and oxidation. An inception model links the gas-phase mechanism with the smallest particle section. Predictions are compared with experimental data in two laminar coflowing diffusion flames of ethylene for which experimental profiles of stable species, aromatic compounds, high-molecular-mass precursor species, and soot are available. The predictions show good agreement with data for total particulates, defined as the sum of soot plus nano-organic carbon particles. The model has a continuous size distribution and is able to address nanoparticles which comprise a significant part of the total particle loading. A conclusion from the sensitivity analysis is that the inception process, the molecular growth process by aromatic addition on particle nuclei, and surface addition of C2H2 all play important roles which need to be studied in greater detail to predict the right size distribution and volume fraction of particulates formed in flames. 相似文献
109.
《Combustion and Flame》1985,59(2):189-196
Spectral intensities from the chemiluminescent reaction CO + O → CO2 + hv have been measured in the range 2600–7000 Å from reacting mixtures of H2O2COCO2argon, shock heated in a shock tube to temperatures of 1300 and 2700K. Intergrals of the photon production rate yield an overall rate coefficient I0 = 6.8 (±0.6) × 105, exp(− 1960/T) cm3 mole−1 s−1. Extrapolated to 300K, this rate coefficient is in excellent agreement with the room temperature measurements of Pravilov. 相似文献
110.
《Combustion and Flame》1984,56(1):1-27
An experimental and modeling study of the preignition oxidation of methane and its sensitization by propane is reported. The ignition delay times were measured behind reflected shock waves at two different locations along the shock tube in 9.5% CH4-19.0% O2-Ar mixtures with 0.19, 0.475, 0.95, and 1.9% C3H8 added. The experiments were performed at a nearly constant density of approximately 2 × 10−5 mol/cm3 over a temperature range of 1300–1600K. A computer model, composed of 140 reactions and 34 species, was able to predict the experimental results obtained in this and earlier studies. The model was subjected to a sensitivity analysis, which was performed using the saturated-design technique. The oxidation of methane during the induction period was found to proceed through three distinct phases: initiation, oxidation of CH3 by O2, and oxidation of CH3 by HO2. The sensitization by propane was found to be primarily determined by the decomposition of the propane molecule. 相似文献