Advanced Materials Research Vols. 875-877

Abstract: Currently, there are different kinds of alternative fuels called "clean fuels" within which hydrogen gas is considered. The hydrogen can be produced by various methods. The aim of this research is producing hydrogen gas by gasification of biomass in a fixed bed reactor, using a gaseous mixture with a high energy potential.

Abstract: A novel ammonia-water power cycle is proposed, which uses low-temperature heat sources such as oceanic-thermal, biomass as well as industrial waste heats. An ejector is introduced between the turbine and the absorber. The main emphasis is placed on the energy and exergy analysis to guide the thermodynamic improvement for the cycle; parametric analysis is conducted to investigate the effects of thermodynamic parameters on the cycle performances. The result shows that the thermal efficiency can reach to 5.31% and the exergitic efficiency varies between 13.3% and 24.4% under the given condition. In addition, the generator pressure, the deflation ratio variation and the turbine outlet depressurization made by ejector have significant effects on the performance of the power cycle.

Abstract: A revolutionary new technology for cooling and refrigeration, based on applications of nonlinear coupled oscillations to the atomization and evaporation of liquids, opens the way to order-of-magnitude reductions in the energy requirements for cooling and refrigeration in a wide range of applications. The basic principles of the new cooling method are presented, together with results of certified measurements carried out on laboratory prototypes of the new cooling process.

Abstract: The inter-harmonic spectrum of an electrical voltage or current from discrete Fourier transform can not only be caused by genuine inter-harmonic components, but can also be caused by other system disturbances. Therefore, the existence determination of genuine inter-harmonic s from the spectrum becomes the premise for further calculation of inter-harmonic parameters. From the theoretical perspective, this paper firstly analyzes and points out that the waveform difference among each cycle in the analysis window is the cause of the existence of inter-harmonic spectrum, and then presents a method to determine the existence of genuine inter-harmonic components, which is based on inter-harmonic time-frequency contour chart and the component appearance rate. The presented method firstly performs continuous discrete Fourier transform on the captured signal with certain duration and obtains the corresponding absolute time-frequency matrix, and then the genuine inter-harmonics can be distinguished based on the component appearance rate of the matrix and the criterion threshold. The method is easy to implement with clear principle, it can distinguish the genuine inter-harmonic s from the measured signal. The analysis on several data groups from real measurements verifies the effectiveness and the practicability of the method.

Abstract: To improve the connected-grid wind power quality as well as profit, the pumped storage station is used to configure the wind farm. The economical benefit and deviation models are built as objective functions, the united operation is based on fuzzy multi-objective evolutionary algorithm (FMOEA). In order to outstand method advantages, the results are compared with the consequences from each objective function that are optimized respectively. The analysis shows that a wind farm with a pumped storage station is as a combined system and uses FMOEA, not only improving profit, but also paying attention to reduce deviation so that can achieve the total net profit increase.

Abstract: Accurate regional wind power forecasting guarantees the security and economics of the power system integrated with large scale of wind power. Aiming at the gross wind power output of the whole regional grid area, existing regional wind power forecasting methods fails to characterize the locally gross output power of the wind farm aggregation forming a power flow interface with specified flow restraints. In this paper, the work flow of the power flow oriented regional wind power forecasting method based on whole-grid regional wind power forecasting methods was presented first. Then, the data preparation, data preprocessing and the mathematical description of the algorithm for our method were presented. Finally, the case study proved the feasibility and effectiveness of our method. The conclusion indicates that the method presented in this paper implements a multiple temporal and spatial scale regional win power forecasting technology, which can obviously improve the accuracy of regional wind power forecasting, relieve the pressure for the grid side and improve the utilization rate of wind power.

Abstract: By study on underlying coal and strata pressure-relief principle and the gas extraction technique under upper protective layer mining, we obtain the stress change and distribution law of underlying coal-rock mass. We analyze the deformation law and fracture development characteristics of underlying coal-rock mass movement. With mining proceeding ahead, the total floor coal and rock experiences compression deformation first, then expansion deformation and re-compaction of the continuous periodic destruction. Based on different development characteristics and status of underlying coal-rock mass, the underlying coal-rock mass under an effect of upper protective layer mining was divided into the floor heave fracture zone and the floor heave deformation zone in this paper. The permeability coefficient of change law of underlying the coal seam as follows: the original value-small decreasing-increasing greatly-reducing-stability at last. The field test for upper protective layer mining of Zhang-ji coal mine of Huainan shows that the effect of pressure relief of protected seam is very good. So it eliminates the risk of gas outburst, ensuring safety mining of the protected seam. The research has an important significance for safety and efficient production under similar exploitation conditions of low-permeability with high gas and outburst risk coal seam.

Abstract: Tubular buckled inside wellbore section of oil or gas wells may cause problems such as: Casing wear/failure, Eliminates the transmission of axial load to the Bit, Drillpipe fatigue, Bit direction change, Severe drag and torque, Tubing seal failure, Connection failure. According to what mentioned above, it would be necessary to make an investigation on the effect of drag and/or torque on buckling of tubular inside horizontal wellbore (the so-called torque-drag-buckling relationship), the study depends mainly on conducting experimental tests and develop Finite Element Model, and utilize the results to predict the tubular behavior under different circumstances of torque and drag, also these results were compared and verified with some of theoretical approaches. Results obtained from this study indicates that torsion load had a little effect on buckling of tubular in horizontal section, this effect increase with decrease in pipe stiffness. Helical buckling tends to increase highly drag force, and thus eliminates transmission of axial load to the bit. Drag force tend to increase with torsion load as a result drag increase helical buckling. For prediction of helical buckling Lubinski and Woods, Gao Deli and Chen et. al provided a good agreement with one-end hinge condition, and Dellinger equation is the best for two-end hinge boundary condition.

Abstract: The spirally water wall are distributed on the plane and divided into seven sections. The mean heat flux of each section is determined using furnace thermal calculation in sections. The value of the pressure and temperature concerning the working medium at inlet and outlet of each tube are established by calculating enthalpy increasing. The vaporizing processes of the working medium in the spiral tube under the three working conditions: 70%BMCR, 65%BMCR and 60%BMCR are analyzed. The state of the working medium and the possibility of the heat transfer deterioration are estimated. More reliable references are provided for the appearance of the heat transfer deterioration.

Abstract: Distributed power system, especially the distributed power and micro-grid system in the mountain villages, islands and remote areas, has many advantages, which can be used as an effective supplement of grid to help solve the problem of electricity supply. The connected-grid inverter needs to be able to work in both grid mode and island operation mode in order to ensure the safety of the local critical load. The paper proposed the seamless switching control strategy for two modes of switching. The experimental results verify the property of the topology structure and control strategy.