Advanced Materials Research Vols. 236-238

Abstract: Numerical simulation of mass transfer in cathode diffusion layer will be helpful for understanding the mass transfer characteristics and predicting the output characteristics of proton exchange membrane (PEM) fuel cell. In this paper, Lattice Boltzmann method was adopted to simulate mass transfer in cathode diffusion layer of PEM fuel cell, analyze the effect of porous diffusion layer microstructure. The effects of porosity, the pore size and gradual porosity on mass transfer were discussed, and the relationship between liquid saturation and diffusion coefficient was correlated under the existence of liquid water. The results can be used to diffusion layer design and performance analysis of PEM fuel cell.

Abstract: CO₂ Reforming of CH₄ to syngas by Ni/γ-Al₂O₃ catalyst combined with cold plasma jet was investigated. The higher selectivity of H₂ and CO, and higher energy efficiency were obtained compared with other kinds of plasmas. Under the experimental conditions of flow rate at CH₄=200 NL/h, CO₂=300 NL/h, N₂=500 NL/h, the input power at 0.77 kW, for the operation of plasma only, the conversions of CH₄ and CO₂ were 45.68% and 34.03%, the selectivity of CO and H₂ were 85.41% and 78.11%, the energy efficiency was 2.94 mmol/kJ, respectively. Keeping the same conditions, the catalysts of 12%Ni/γ-Al₂O₃ were put following the plasma discharge zone. Without accessorial calefaction to catalysts, the conversions of CH₄ and CO₂ were increased by 14.38% and 6.32%, the yield of H₂ and CO increased by 18.76% and 11.38%, the energy efficiency reached at 3.67 mmol/kJ, respectively. It was strongly verified that the cooperation action of clod plasma jet with catalysts at reforming of CH₄/CO₂.

Abstract: A novel method of dynamic ice forming, liquid-liquid circulating fluidized bed, was studied using direct contact heat transfer between drops and the coolant for ice storage system. In order to model multiphase flows and heat transfer in circulating fluidized bed, a numerical model was developed. Exergy discharge was discussed for liquid-liquid circulating fluidized bed based on the second law of thermodynamics. Numerical method was used to study the influence of operating parameters, such as the droplet diameter and the inlet temperature or velocity average of liquid phase, on the ice-making performance and total exergy discharge in the dynamic ice-making process.

Abstract: The electrolyte flow states of all vanadium redox flow battery (VRB) have a direct effect on the battery performance and life. To reveal the electrolyte distribution in the battery, the computation fluid dynamics (CFD) method was used to simulate a parallel flow field. A hydraulics experiment and a battery performance experiment were carried out to confirm the simulated results. The results show that the predicted information agreed well with the experimental results. The electrolyte has a concentrated distribution in the central region of the parallel flow field and the disturbed flow and then vortex flow areas mainly appear in the inlet and outlet regions. The higher flux of electrolyte is helpful to uniform the distributions and to reduce the impact of flow irregularity on the battery performance. The battery with the flow field generates a power density of 15.9 mW∙cm^-2, and the coulombic, voltage and energy efficiency is up to 90.5%, 74.0% and 67.2% at a current density of 20 mA·cm^-2.

Abstract: The difficulties during the exploration and development of the reservoirs which are low pressure-permeability, low pressure fractured hydrocarbon or energy depleted put multi-requirements on drilling fluid, which include the capacity of inhibiting and sealing to avoid down hole losses and formation caving in the situation where different pressure coefficients exist in the same open hole, good compatibility with underbalanced drilling fluid such as air, mist, foam etc, good solids-carrying capacity and formation damage control according to varies kinds of well completion in different types of well like vertical, horizontal or multilateral well. Thus a novel multifunctional bionic fuzzy-ball drilling fluid was invented under the auspice of National Key Project. The density of the fluid which is solid free can reach to 0.8~1.0 g/cm³ with conventional drilling equipments. Also, its density can be above 1.0 g/cm³ by adding inert weighting additives to adapt to near-balanced or under-balanced drilling. Good sealing ability can avoid down hole losses, formation caving in opening and low-pressure layers above 1000m. The ratio of yield value and plastic viscosity can be above 1.0 Pa/mPa·s, which makes good performance in hole cleaning under low pump delivery with conventional drilling equipments. Being compatible with air, it can be used in water producing, sloughing formation and completions without converting to other types of drilling fluid system. Bionic fuzzy-ball drilling fluid has been used in more than 10 wells, which have the problems such as water production, formation caving and severe losses, and applied to air drilling. The field applications of bionic fuzzy-ball drilling fluid can be demonstrated by introducing the “U” shape horizontal well DFS-02-H2, multilateral well FL-H2-L, artesian flowing and formation caving well J35, air drilled well CLY22 and low pressure gas well Mo 80-C1.

Abstract: To compare the extraction rate of the organic components of coal between direct ultrasonic extraction and traditional soxhlet extraction, samples were selected from tectonic coal and original bituminous coal in Pingdingshan 8th coal mine and 5th coal mine. Compared the extraction time of two different extraction methods under the same extraction rate, the experimental results showed that the direct ultrasonic extraction rate was 3.6942% under the condition that coal was 8th coal mine tectonic coal, solvent was pyridine, extraction time was 6min and solvent volume was 60mL, while soxhlet extraction time was 14.59h in the same extraction rate. The extraction efficiency of the direct ultrasonic extraction was 145.9 times that of the soxhlet extraction. The ultrasonic extraction was a simplify working with fast extraction speed, sample capacity, energy saving, economy and environmental friendly. It also didn’t require heating which could avoid the influence of high-temperature on components extracted.

Abstract: With enhanced awareness of energy conservation and environmental protection, more attention has been paid to the high moisture content of the filtration products used in the flotation process as commonly employed in coal preparation plants. In this paper, we choose fine coal (–0.5mm) samples obtained from the Xiqu Coal Preparation Plant in China as our research objective. Tests were performed under three different experimental conditions: direct pressure filtration, electrolysis pressure filtration, and electricity decompression filtration with different electrodes. Thus our aim was the evaluation of the impact of electrodes on the electrolysis-pressure-filtration effect on fine coal dewatering. The results of this study indicate that when the coal slurry concentration is 400g/L, and when the electrode is aluminum-aluminum (90V, 14min), we can achieve the best effect and the lowest moisture content of the filter cake, which is 10%. The electrolysis pressure filter has a high dewatering efficiency, an advanced technical index, requires little power consumption (obviously energy-saving), needs only a small amount of maintenance, and is stable and reliable in operation, Thus the electrolysis pressure filter is the most effective and economical processing equipment for fine coal dewatering and has prospects for broad application.

Abstract: A new four column multi-effects distillation technology for the production of edible alcohol is simulated and optimized by AspenPlus simulation software on the basis of energy conservation technique of multi-effects distillation. The optimized technical parameters are summed up as follows: the theoretical number of trays and top pressure of the beer column, aldehyde removing column, refining column 1 and refining column 2 are 17, 40, 62, 50 and 0.4 atm, 0.4atm, 1.9 atm, 6.0 atm respectively. Only the refining column 2 needs extra heat source, the calculated saturated steam (7 atm) consumption is 1.1t/t edible alcohol product; ethanol content in product edible alcohol is 95.6%(v/v), meets the GB10343-2002 high grade. The yield of the ethanol product is higher than 95%.

Abstract: The optimization of heat exchanger networks (HEN) is a typical MINLP problem. For large-scale HEN, it is difficult to solve this problem globally. After optimization, the large-scale HEN is divided into several independent sub-networks automatically. The sub-network is defined as a part of the HEN in which the streams have no heat transfer with the streams outside the sub-network. If a HEN can be divided into two or more sub-networks, then, these sub-networks are independent from each other. Based on optimization of sub-networks, a new method which can solve large-scale HEN problem efficiently is proposed.

Abstract: Toluene insolubles (TI) in coal tar is harmful to the downstream hydrotreating, and it may be difficult to be removed by conventional filtration. The TI is separated from coal tar which is washed by toluene and centrifugated at 2000 rpm and analyzed by Fourier transform infrared (FTIR) spectra, scanning electron microscopy (SEM), particle size measurements, X-ray Diffraction analyses (XRD) and elemental analysis. It is concluded that TI in coal tar is present typically as globular aggregates. The primary particles range in size from less than 0.5μm to about 20μm. Characterization of TI in the coal tar showed that it is a nitrogen and oxygen rich material. TI is mainly inorganic elements representative of quartz, albite and calcite associated with kerogen material.