bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Assessment of a Multi-Effect Solar Desalination System in Southern China
Authors: Chen Jing , Chen Shun Quan , Zhao Yun Mo , Du Ruxu
Published: June 2012

This paper presents the thermal performance of a multi-effect distillation (MED) solar desalination unit located in southern China. The system was designed and installed in April 2011, and has been in operation since that time till now. The seawater desalination system is driven by 60 m2 all-glass vacuum tubes solar collector with an additional rainwater utilization system to produce fresh water on both sunny and rainy days. The preliminary experimental results show that the water production of the system for per unit of solar collector area could reach up to more than 12.5kg/m2·day under the fine weather conditions. Water production of the system was stable in long period and the annual production could reach to 387.5 m3 in southern China. The economic performance of the system is also discussed. The cost of water production is estimated approximately 4.15 $/m3 for the 15-year service life.
The Logical Choice of Auxiliary Heat Source for Solar Energy Water Heating System
Authors: Liu Xue Lai , Wang Guan Zhu , Li Yong An , Zhang Xiao Feng
Published: June 2012

This article describes the solar hot water system, and establishes the computational model of hot water system. It analyzes the economical efficiency of solar water heaters which equipped with electric water heaters, gas water heaters and air-source heat pump water heaters. The results show that the initial investment of the system which equipped with an electric water heater and a gas water heater is almost, but the operating cost which equipped with a gas water heater system is lower. The operating cost which equipped with an air-source heat pump water heater is the lowest, though the initial investment is the highest. The solar hot water system which equipped with an air-source heat pump water heater has important reference value for going low-carbon economy road in China.
Numerical Simulation of the Thermal Performance of Cable Radiant Heating Floors with Different Structure
Authors: Yan Quan Ying , Jin Li Li
Published: June 2012

In this paper, three kinds of mathematical models of cable heated radiant floors were established, and numerical simulation of heat transfer process for these heated floors were carried on by using finite element method and ANSYS software. The rule of temperature distribution, surface heat flux distribution and downward heat loss of these three floor structures were given and compared. The results can provide references for a further optimization, design and application of low temperature radiant heating floor.
Dynamic Study on Vacuum Pyrolysis Reaction of Chinese Fir Sawdust Biomass
Authors: Yang Su Wen , Yi Jian Min , Qiu Ke Qiang , Deng Xin , Chen Jian Shan
Published: June 2012

This thesis does thermal gravimetric analysis（TGA）studies on Chinese fir sawdust biomass by integrated thermal analyzer under vacuum conditions. Through the analysis on lostmass curve at different heating rate of 10, 15, 20 and 30°C/min, we found the process of Chinese fir sawdust vacuum pyrolysis can be mainly divided into three stages: evaporation of free water and combined water desorption, rapid lostmass of pyrolysis and slow decomposition of residues. The lostmass major temperature range is between 250 ~ 450°C, the peak temperature is between 365 ~ 400°C. When the pyrolysis temperature is 500°C, vacuum pyrolysis reaction of Chinese fir sawdust has basically completed. As the heating rate rises, the lostmass curve is moving to the right, the peak temperature is shifting to higher temperature, and the temperature range of thermal decomposition reaction widens significantly. According to experimental datas, we tried to obtain the vacuum pyrolysis dynamic parameters of Chinese fir sawdust, and the results are that the apparent activation energy of vacuum pyrolysis reaction of Chinese fir sawdust biomass is 128.34kJ/mol, with the pre-exponential factor being 6.42×109 and reaction order being 1.08, similar to first order reaction.
Evalution of the Pyrolytic and Kinetics Characteristics of Xanthoceras sorbifolia Oil
Authors: Sheng Gui Hua , Zhou Quan Cheng , Li De Mao
Published: June 2012

The pyrolytic characteristics and kinetics of Xanthoceras sorbifolia oil were investigated at heating rates of 10, 20 and 30 °C min-1 in an inert atmosphere. The most probable mechanism function and activation energy pre-exponential factors were calculated by the Popescu, FWO and KAS methods. Three stages appeared during pyrolysis: moisture evaporation, primary devolatilization and residual decomposition. Significant differences in the average activation energy, thermal stability, final residuals and reaction rates of the X. sorbifolia oil at different heating rate were observed. Stage II of the X. sorbifolia oil could be described by the Mampel Power equation 22 (n=0.25). The average activation energy of X. sorbifolia oil was 346 kJ mol-1.
Experimental Study of Effecting Factors for Plant Straw Densification
Authors: Yu Xin Qi , Wan Xin Lei , Liu Qing Gang
Published: June 2012

In this paper, plant straw densification technology has been studied. The corn straw was taken as raw material in the experiment. The influences of raw material moisture content, densification pressure and raw material size to the compact process have been studied. The results show that the 13%~18% moisture content of the corn straw is the best scope in compact process. When the raw materials are densified at a pressure of 60MPa, the products have smooth surface, high density. While the pressure continuously increases, the increase of density is not obvious. The raw material size 10~20mm are suitable for densification.
Finite Element Analysis for Normal-Temperature Wet Briquetting of Straws
Authors: Hu Jian Jun , Lei Ting Zhou , Shen Sheng Qiang , Zhang Quan Guo
Published: June 2012

As one of important technologies for briquettes production from straws, the normal-temperature wet briquetting technology of straws shows important practical significance in place of fossil fuels that are progressively reduced. According to the characteristics of the normal-temperature wet briquetting of straws having large displacement and large strain, this article provided a finite element calculation method for non-linear straw problems using the large-deformation elastic-plasticity principle. Based on description of straw status by Lagrange method, analyses were performed for deformation gradient tensor, displacement gradient tensor and rigid body movement, and then finite element equations were established for the normal-temperature wet briquetting of straws according to the Green strain, Drucker-Prager criterion and balance principle, providing references for numerical simulation for the normal-temperature wet briquetting of straws with computer software.
Heterogeneous Acid-Catalyzed Hydrolysis of Cellulose
Authors: Liu Jia Xin , Huang Yu Dong
Published: June 2012

With the world’s focus on reducing our dependency on fossil fuel resources, one of the challenges will be the development of efficient catalysts for selective transformation of cellulosic biomass. Hydrolysis of cellulose to glucose is a key technology for effective use of lignocellulose because glucose can be efficiently converted into various chemicals, biofuels, foods, and medicines. Thus far, substantial efforts have been devoted to the degradation of cellulose but these processes have significant drawbacks. Some of these problems can potentially be overcome with the application of solid acid catalysts. In this paper, recent studies on heterogeneous acid-catalyzed hydrolysis of cellulose are summarized.
Improving Flow Properties of Rapeseed-Based Biodiesel at Low Temperatures
Authors: Chen Xiu , Lu Cui Ying , Lai Yong Bin , Ge Wu Jie , Li Su Rong , Tao Jun
Published: June 2012

The cold flow properties of rapeseed-based biodiesel (RME) were studied by gas chromatography-mass spectrometry (GC-MS), multifunctional low temperature tester and thermal analysis. Two approaches for reducing cold filter plugging point (CFPP) of RME were investigated: blending with winter petrodiesel, treating with cold flow improver (CFI) additives and the effect of CFI to combustion characteristics of RME. A good correlation model was proposed for prediction CFPP by RME blending ratio. The study shows that the RME was mainly composed of fatty acid methyl esters (FAME): C14:0–C24:0, C16:1–C22:1, C18:2 and C18:3. The mass fraction of saturated fatty acid methyl esters (SFAME) and unsaturated fatty acid methyl esters (UFAME) was 14.69% and 83.40%, respectively. The CFPP of RME was -7 °C. Blending with -10 petrodiesel (-10PD) decreased the CFPP to -12 °C. Treating with CFI additives (volume fraction ≤ 1.5%) decreased the CFPP of RME and RME/-10PD to -11 and -28 °C, respectively. Small amount of CFI additives hardly affected combustion characteristics of biodiesel. This study has effectively improved cold flow properties of biodiesel and provided guide for using biodiesel at low temperatures.
Formation of a Low Reflective Surface on Silicon Solar Cells by Chemical Treatment Using Ag-Assisted Electroless Etching
Authors: Ma Guo Feng , Zhang Hong Ling , Yang Xue Fei
Published: June 2012

The Ag-assisted electroless etching of p-type silicon substrate in HF/H2O2 solution at room temperature was investigated. The porous silicon layer was formed in a mixed solution of H2O2 and HF by using screen-printed Ag front electrodes as the catalyst. And influence of the different concentration etching solution (HF and AgNO3) on the porous silicon layer was study by scanning electron microscopy (SEM). Through investigation of the track of catalyst particles, it was shown that Ag really catalyses the etching of silicon underneath Ag particle.
Production Methods without Waste Water of Biodiesel Based on Solid Neutralizing Agent
Authors: Yang Hai Yan , Li Min , Chen Fu Ming , Xiong Dong Lu
Published: June 2012

In this article, the preparation and application of solid neutralizing agent was studied, liquid acid to purify crude biodiesel traditionally was substituted for the solid neutralizing agent and acquired satisfactory results. It was the biggest advantage to the process to apply solid neutralizing agent to purify crude biodiesel that became more simple than former and may not produce wastewater, the drawback of production biodiesel at present can be successful improved.
Study of Biomass Pyrolysis with TG-FTIR Technique
Authors: Wang Jian Mei , Cai Fei Peng , Jin Fu Qiang , Wang Bo , Jiang Bo
Published: June 2012

The pyrolysis behaviors of cotton stalk, corn stalk and corn cob have been investigated with the thermogaravimetric ananlysis(TGA) coupled with Fourier transform infrared spectrometer(FTIR). The results from TGA show that there are two reaction stages in the pyrolysis process, corn cob is easier to decomposition than others at the same temperature, and their pyrolysis process is different from each other. Different chemical component ratio maybe link with the variable biomass pyrolysis behaviors. The corn cob yield the most organic compound for its highest content of cellulose and the cotton stalk yield the most non-condensable gas in addition to H2 for its highest content of hemicellulose from the integrated data of peak area. Thus, the content of cellulose and hemicellulose have an important role in the biomass pyrolisis.
The Assessment of Three Straw Utilization Project of Rural Energy
Authors: Ai Ping , Wang Dian Long , Yan Shui Ping , Wang Yuan Yuan , Zhang Yan Lin
Published: June 2012

As a large agricultural country, China ranks first in the world of the output of crop residues. However, due to the decreasing requirement of rural living energy usage for straw, the surplus of straw is extremely severely in rural area. Recently, the central government encouraged greatly the straw utilization, and the large-scale straw utilization is the main content of the rural energy now. As for three modes of large-scale straw utilization in rural energy fields such as: straw gasification, straw biogas and straw molding fuel (solidification/carbonization), these modes are planned to be compared, analyzed and evaluated in this paper to capably provide selection reference for large-scale utilization of straw and boost the development of straw resource utilization in rural China.
Effect of Loading Rates on the Nominal Bonding Strength between Soft Substrate and Photovoltaic Silicon Wafer
Authors: Liu Guo Ning , Zhao Hua Dong , Yang Wei , Ma Sheng Gang , Zhao Ming Hao
Published: June 2012

Aiming at expanding and extending the application of photovoltaic energy technology into a bigger scope, a kind of soft substrate with multilayer structure is designed and fabricated to be bonded with photovoltaic silicon wafer to manufacture photovoltaic system. Pure aluminum thin film is introduced in the designed structure, which consists of mainly organic polymeric materials, to improve the thermal conducting behavior and anti-corrosion properties of the whole photovoltaic system. To study the reliability of the eventual structure with photovoltaic module of silicon wafer, various loading rates are chosen to measure the nominal bonding strength between the soft substrate and photovoltaic module.
Isolation and Identification of Photosynthetic Bacteria and their Hydrogen Production Characterization
Authors: Zhu Yan Yan , Zhang Quan Guo , Han Bin Xu , Jing Yan Yan
Published: June 2012

Using special culture medium, dominant photosynthetic bacterias were enriched from sewage silt and paddy fields with plentiful light and organic compounds. Five strains of photosynthetic bacteria capable of producing hydrogen were purified and isolated by gradual dilution and double—deck solid medium. The analysis of the gene sequence information of 1 6SrDNA was carried out, and the five strains were identified as Rhodospirillum rubrum,R.capsulata, R.pulastris, Rhodobacter capsulatus, Rhodobacter capsulatus . Moreover, it was found that with Optimized medium formula, hydrogen production can be achieved 204h, the maximum hydrogen production capacity of 3.41L, the maximum hydrogen production rate was 44.17ml / (L • h),the highest hydrogen content of 46.73%.
Performances and Emissions of a DI Supercharged Diesel Engine Fuelled with Soybean Biodiesel and its Blends
Authors: Ma Zhi Yi , Zhang Chun Hua , Li Yang Yang , Song Jian Tong
Published: June 2012

Biodiesel is one kind of renewable fuel produced from biomass oil. To optimize the application of biodiesel on vehicle diesel engines, we conducted the tests on a four cylinder turbocharged direct injection (DI) diesel engine fuelled with biodiesel-diesel blends of different ratios, measured their power outputs, fuel consumption and emissions, and compared with those of diesel fuel. Experimental results show that fuelled with biodiesel, at external characteristics (speed characteristics of full load), the power performance is almost the same, brake specific energy consumption (BSEC) decreases, smoke and HC emissions decrease, and NOx and CO emissions increase; at load characteristics, BSEC decreases, smoke emission decreases at high loads and keeps almost no change at low and middle loads, NOx emission increases, HC emission decreases at low and middle loads and keeps the same at high loads, and CO emission maintains the same. B20 (biodiesel content of 20%) is an optimum solution for vehicle engines under comprehensive analysis of performances and emissions.
Buckling Analysis on Large Wind Turbine Tower
Authors: Yang Cong Xin , Liu Yi Xiong , Wang Bin
Published: June 2012

The buckling of 2.5MW horizontal axis wind turbine tower tube (5.8m*3.2m*95.2m) is studied by theoretical analysis and numerical simulation. The buckling critical value of tower under axial force is found by theoretical method. The buckling modal of tower under axial force, wind pressure, bending moment and lateral force is simulated by ANSYS software. The buckling of tower with opening and frame at the bottom is also simulated by ANSYS software. The results show that both load and opening have influence on buckling performance, different load and opening have different impact to buckling of tower tube.
Numerical Simulation on the Flow Control by Mounting Indented Gurney Flaps for a Wind Turbine
Authors: Zhao Wan Li , Zheng Xiao Lei
Published: June 2012

Numerical investigation of large thick and low Reynolds airfoil of wind turbines by mounting indented Gurney flaps was carried out. The influenced rules of the position of Gurney flaps on the aerodynamic performance of airfoil under same height of flaps were achieved, and the optimal position of Gurney flap was presented. At last, the mechanism of wind turbine performance controlled by Gurney flap was discussed. The results can provide the theoretical guidance and technical support to wind turbines control in practical engineering.
On the Comprehensive Management of the Development of Wind Energy in China
Authors: Niu Dong Xiao , Wu Huan Miao , Ma Zhen , Liu Jin Peng , Xu Chao Chen
Published: June 2012

In recent years, wind energy develops rapidly in China and its comprehensive management research deepens continuously. This paper studies the wind energy level and summarizes the current development situation of our country. The study puts forward a forecasting analysis using Grey Forecasting Theory, and proposes several suggestions for the comprehensive development. The result has reference for improving the management level of the wind power.
Research of Offshore Wind Power Generation Technology
Authors: Guo Yi Ni , Zhang Yan , Wang Jian , Huang Ye
Published: June 2012

Offshore wind farm development direction is from shallow sea to sea . In this paper, according to the current on the wind power base also can not meet the requirements of the problem deep, analysed the base cost will not be particularly high reason. In view of the Hainan offshore wind power, put forward the design train of thought, the analysis obtained an ideal design model.
Research on the Problems of Wind Power Grid-Connecting
Authors: Xiao Yang , Chao Hui , Xia Chao
Published: June 2012

Under the condition of energy shortage and environment worsen so far, wind power generation has got much improvement. The article makes research to main problems existing in wind power grid-connecting, which inludes the following items: 1) Main types and characteristics of present grid-connected wind generators; 2) Main difference of the operation characteristics between grid-connected wind plant and conventional engergy power plant; 3) The influence to power quality and power system stability caused by grid-connected wind plant and the measures taken to deal with such influence; 4) The particularity of wind power enterprise in China; 5) Domestic and foreign standards’ main requirements to wind power grid-connecting; 6) Three important issues needed urgently research: wind generator and wind plant modeling, wind power forecasting, cooperating control technics between wind plants and power grid. The development of wind power enterprise will bring people remarkable economic benefit and social benefit.
Structural Analysis for the Blades of a Small Horizontal-Axis Wind Turbine
Authors: Wang Sheng Huan , Huang Kuo Yi , Tsai Gwo Chung
Published: June 2012

This study discussed the structural analysis of blades of a small horizontal-axis wind turbine (HAWT). The computational fluid dynamics (CFD) is combined with the computational solid mechanics (CSM) into the one-way fluid-solid interaction. The aerodynamic force calculated by CFD is loaded on the structure, and the structural deformation and stress distribution are calculated using CSM. The physical model in the study is a HAWT blade with the rated power output of 500 W, and the material is engineering plastics. The Young's modulus of material is estimated according to the result of blade static load test. The accuracy of structural analysis is verified, and the blades in rated operating state are analyzed for fatigue failure. The blades in no-load running and rotor parked state are analyzed for ultimate strength. The blades of a wind turbine have large length-to-diameter ratio, and the structure approximates to a cantilever. The accuracy of linear analysis is good under a small load. However, as the load increases, the effect of geometric deformation should be considered to improve the precision of analysis. Therefore, the geometrical nonlinearity is used in this study to analyze the structure of blades in three operating states. The results showed that the safety of blades can meet the IEC 61400-2 international standard. In addition, the required safe distance between blades and tower is estimated at 157 mm according to the critical deformation analysis. According to the natural vibration modal analysis, the blades should be prevented from running at the rotating speed of 744 rpm that causes resonance for long.
Study on the Affected Factors of Aerodynamic Performance of Vertical Axis Wind Turbine
Authors: Sun Ke , Liao Kang Ping , Zhang Jian Hua , Ye Xiao Rong
Published: June 2012

The study of aerodynamic performance of vertical axis wind turbine is the basis of the VAWT design. The double disk multiple stream-tube, one of the numerical models for predicting the aerodynamic performance of the wind turbine, was used to calculate the aerodynamic performance of the Sandia DOE-17m VAWT. As shown in the comparison of the calculation results and the field test data, the DDMT model is efficient in predicting the aerodynamic performance. And then, a deep analysis of the inherent mechanisms that how the geometric parameters of wind turbine rotor like height to diameter ratio, solidity, chord and the number of blades affect the aerodynamic performance of turbine was made in the present work. The results will be the theoretical basis for the optimization of the design in aerodynamic performance of VAWT in the future work.
Testbed for a Wind Turbine with Magnetic Bearing
Authors: Vorwaller M. Ryan , Lin Kuo Chi , Gou Ji Hua , Ham Chan , Joo Young Hoon
Published: June 2012

World-wide demands for sustainable energy have brought increased attention to the improvement of wind turbine technology. Magnetic bearings promise to improve wind turbine performance by reducing frictional losses and mitigating vibration due to rotor imbalance and wind disturbances. However, testing must be performed to validate and quantify these advantages if magnetic bearings are to be used efficiently. Therefore, a practical testbed for a wind turbine with a magnetic bearing system has been developed, including the design of a passive rare earth magnetic bearing and fixture. This testbed will provide experimental vibration and efficiency data needed to extend past research in wind turbine modeling and design to include recent advances in magnetic bearing technology.
The Application of Modified Delphi Method in the Topological Optimization Site Selection of Offshore Wind Farm
Authors: Jing Ya Tao , Hu Li Wei , Yue Jiang
Published: June 2012

Core of the topological optimization site selection of offshore wind farm is Delphi method. The paper divides the investigated experts into industry experts and professional experts, which respectively score the weighting coefficient and its value of the influence factors of offshore wind farm. The separate marking scheme can well develop the ability of experts, avoid the specialty bias and thereby improve the assessment accuracy. Another modification is to apply the accumulative vote method in the first stage of topological optimization site selection instead of designers’ own judgments, which gives a good solution to classify the disputed factors, and avoids fault or deviation due to the knowledge deficiency of designers. In addition, the data analysis results should be reassessed by the industry experts. And in company with the reassessment opinion the data analysis results are the basis for designers to determine the best sea area for offshore wind farm construction, which gives an extra guarantee for the scientific site selection.
Analysis of Wind Turbine Gearbox Based on RomaxWIND Flexible FE Structures
Authors: Su You Liang , Wang Chun Xiu , Jiang Wei , Sun Li
Published: June 2012

Wind turbine gearbox is a key component to transmit power in wind turbine driveline. It is necessary for gearbox to have high reliability and durable quality, and so, it is obviously important to analyze the reliability of key components and the root of common failure. By means of RomaxWIND software, gearbox simulation model was built which is based on the flexible FE structures. Considering the effects of flexible FE structures, such as housing and ring gear, and capturing system effects, analysis is performed to estimate the performance of components under 20 years’ LDD, and the bearing and gear report were generated. Gear mesh misalignment is one of the major gearbox failure causes. In view of it, three different models were built for the analysis of mesh misalignment, the result reveal that the effect of flexible FE structures should not be ignored.
Application of Multiple Level Rules Set in Fault Diagnosis of the Wind Power Generation System
Authors: Gu Gui Mei
Published: June 2012

For the incompletion problem of sensors’ collected data in fault diagnosis of the wind power system, this article puts forward a kind of multiple level rules set based on rough set. First, let the sensors’ collected data go through Fourier transform and extract its feature attributes as well as discrete them. Establish the decision table of fault diagnosis according to attribute values. Then set out from the decision table to establish a multiple level set of nodes with diverse reduced levels and deduce the rules of each node, which has a corresponding belief level. When in reasoning and decision-making of the new data using the multiple level rules set, match the information of the new data with the rule of its corresponding node. Finally, achieve the fault diagnosis of wind power generation system by choosing comprehensive evaluation algorithm. The result of the diagnosis example shows the reliability and accuracy of this method in the diagnosis of fault types for wind power generation system.
Control Strategies of HESS for the Application of Directly Driven WTG
Authors: Wang Li , Li Yan , Sheng Mei Wei , Xu Yi Shan , Yang Zeng Tao , Zhang Bu Han
Published: June 2012

Wind power is the most fast growing energy source in the world while its intermittency and uncertainty generate stability, reliability and power quality problems in the electric grid. A battery/supercapacitor Hybrid Energy Storage System (HESS) is integrated to the directly driven Wind Turbine Generation (WTG) system to achieve a better wind power output characteristic. When integrated to a grid connected WTG, the supercapacitor and battery respectively absorbs the high frequency part and low frequency part of the wind fluctuations. Feedback elements are added to achieve a better performance of this management algorithm. While for a HESS applied to the stand-alone WTG system, the supercapacitor supports the frequency of the isolated system after the islanded operation and PI controllers are used. The control models are developed by the User Definition (UD) module on Power System Analysis Software Package (PSASP). Simulations are carried out to verify the control strategies effective and feasible.
Efficiency Matching Research between PMSG and Fixed Pitch WT
Authors: Li Wen , Zhai Qing Zhi , Li Zheng Hui
Published: June 2012

To improve the utilization of wind power generation system(WPGS), this paper presents a novel matching method on fixed pitch wind turbine(WT) design considered the total efficiency of WPGS. Based on detailed efficiency discussion of permanent magnet synchronous generator (PMSG), at present, the basic data included efficiency of wind power generator (WPG) has mature acquire measures with high accuracy. On the contrary, the efficiency of WT is relatively difficult to obtain accurately, and because of the poor matching research between WPG and WT, there may be a potential problem that the total efficiency of WPGS is not the best. Based on the basic data of the WPG, through the calculation of expected total efficiency and WPG efficiency, compared with the existing curve of the WT features, this method can attain an ideal WT efficiency( ) curve which fit expected total efficiency of WPGS and has a good matching behave with the WPG. It provides a new way for the type selection, design, and manufacture of WT, which is easy calculated, low cost of design, and has good expected matching with system.
On the Effect of Slotted Blades on Savonius Wind Generator Performances by CFD Analysis
Authors: Alaimo Andrea , Milazzo Alberto , Trentacosti Flavio , Esposito Antonio
Published: June 2012

In this paper a new bucket configuration for Savonius wind generator is proposed. With the aim to increase the effect of the overlap ratio RS on the wind turbine performances and to increase the amount of lift force able to produce torque and power, slotted blades are investigated by means of the Computational Fluid Dynamics analysis. The numerical analyses are performed by Comsol Multiphysics® and the results obtained for a Savonius wind turbine with overlap only are compared to numerical and experimental benchmarks. Parametric analyses are performed, for fixed overlap ratio, by varying the slot angle β and the results show that for low angle β the Savonius rotor exploits improved performance at low tip speed ratio λ, evidencing a better starting torque. This circumstance is confirmed by the static analyses performed on the slotted blades in order to investigate the starting characteristic of the proposed Savonius wing generator configuration.
Prediction of Ice Accretion on Wind Turbine with Numerical Method
Authors: Yi Xian , Wang Kai Chun , Ma Hong Lin
Published: June 2012

A three dimensional numerical method and its computer codes, which are suitable to predict the process of horizontal axis wind turbine icing, are presented. The method is composed of the Multiple Reference Frame (MRF) method to calculate flowfield of air, an Eulerian method to compute collection efficiency and a three dimensional icing model companying with an iterative arithmetic for solving the model. Ice accretion on a 1.5 MW horizontal axis wind turbine is then computed with the numerical method, and characteristics of droplet collection efficiency and ice shape/type are obtained. The results show that ice on the hub and blade root is slight and it can be neglected comparing with ice near blade tip. From blade tip to root, ice becomes thinner and glaze ice may changes into rime ice.
Research on Wind Power Prediction by Combining Mesoscale Numerical Model with Neural Network Model
Authors: Yu Feng Ming , Li Xi Cang , Song Jin Hua , Gao Chun Xiang , Jiang Chun Long
Published: June 2012

Effective wind power prediction on wind farm can not only guarantee safe operation of wind farm, but also increase wind power storage and utilization efficiency. This research combines mesoscale numerical weather prediction model with BP neural network model for the use of wind power prediction. WRF model is used to recalculate the meteorological elements of trial wind farm from Jun. 2008 to Jun. 2009, and the accuracy check result shows that the correlation coefficient between predicted value and corresponding measured value of wind speed reaches 0.72. Predictions accuracy of wind direction, air temperature, humidity and air pressure are also precise, which meets the requirement of building BP neural network prediction model. The BP neural network prediction models of output power of 40 wind turbines are established on trial wind farm one by one, to analyze the influence of data normalization method and neuron number at the hidden layer on prediction accuracy. The prediction test every 10 minutes, with the actual effect of 24 hours, is done for 26 days, and prediction accuracy test is conducted by using independent samples. The result shows that relative root mean square error of the output power of the single wind turbine from 24.8% to 32.6%, and the correlation coefficient between predicted value and measured value is from 0.45 to 0.68; relative root mean square error of the whole wind farm is 21.5%, and the correlation coefficient between predicted value and measured value is 0.74.
Investigation of a Hybrid Photovoltaic Thermal Heat Pump System
Authors: Chen Hong Bing , Wei Ping
Published: June 2012

The decrease of photovoltaic (PV) cell temperature by 10 °C is expected to improve the PV electrical efficiency by 0.6-0.7% based on the reference efficiency of 15%. Different cooling liquids like air and water have been introduced to pass across the PVs to reduce the cell temperature, and thus increase the electrical efficiency. In this paper, the refrigerant R134a was used as the cooling liquid and a PV/thermal (PV/T) collector was coupled with a heat pump system acting as the evaporator, which was expected to achieve a better cooling effect and energy performance due to its low boiling temperature. A hybrid PV/T collector, made of 6 glass vacuum tube – PV module – aluminum sheet – cooper tube sandwiches connected in series, worked as the evaporator of the heat pump system. Numerical steady models were established for each component of the heat pump system and part of the PV/T collector/evaporator for predicting their energy performance under the weather data of January 14th at Tibet, China. The results showed that the maximum COP could reach up to 7.6. The daily average thermal efficiency and electrical efficiency were 0.764 and 0.104, respectively.
Symmetrical Short Circuit Current Characteristics of Doubly Fed Induction Generator Wind Turbine with Crowbar Protection
Authors: Zhai Jia Jun , Zhang Bu Han , Wang Kui , Shao Wen , Mao Cheng Xiong
Published: June 2012

Doubly fed induction generator (DFIG) is now becoming one of most widely used wind turbines in global market for wind power generation, due to its outstanding advantages. However, the DFIG is sensitive to grid faults. The DFIG will have to be removed from the grid if there’s no protection appliance in it. Therefore, the crowbar protection is widely used in the world for improving the low voltage ride-through ability of wind turbines. This paper analysed the operating characteristics and short-circuit current of DFIG under symmetrical short-circuit fault with respect to different sags to grid voltage, which on the basis of DFIG wind turbine with crowbar protection. And the expressions of short-circuit current under symmetrical short-circuit fault for DFIG were derived. The effectiveness of the expression was simulated in PSCAD/EMTDC.
The Practice and Enlightenment of the Wind Power Industry in India
Authors: Zhang Chi , Xia Shu Yu
Published: June 2012

Energy is an essential part in life. Currently wind power is the most technologically mature industry in new energy industry, possessed with the most mechanized prospect. The development of Indian wind power industry has gained remarkable achievements, with its wind turbines manufacturing capability and total installation capacity ranking front among current undeveloped countries. Power plants can use wind turbines rather than steam to generate electricity. Being in use with a large scale, wind power can have a significant effect on the growing global need for more energy and efforts to stop climate change. Effective government support, active technological research and international development path are the basic motives to promote the prosperity of Indian wind power industry. With reference to experience from India, enforcing planning, regulation and support and cultivating self innovative ability should be direct countermeasures for our own wind power industry development.
The Research on Direct Drive Permanent Magnet Synchronous Wind Generator Vector Control
Authors: Zhang Jia Ying , Zhang Li Ping
Published: June 2012

Direct drive permanent magnet synchronous generator have the advantages of direct drive, simple structure, high efficiency and so on, in which make it become one of mainstream models within MW wind turbine presently. Making the direct drive permanent magnet wind power generation system as the main research object, based on the principle of the operating characteristics of direct drive permanent magnet synchronous wind generator ( DDPMG ), establish mathematical model of the whole system including wind turbine, direct drive permanent magnet synchronous generator and machine side converter, applying the method of stator flux orientation to make the study of vector control strategy, to build the simulation model of direct drive permanent magnet synchronous generator system with Matlab to simulate the operation of generator when wind speed changes by step, the results validate the reasonableness of the model and the correctness and feasibility of the control strategy.
The Vertical Load Identification Method of the Wind Turbine Support Structure
Authors: Du Ling , Li Fan Chun
Published: June 2012

From the basic equation of dynamics, the precise expression of the relationship ,which is between the horizontal natural frequency and pressure load of the cantilever beam with quality attached to the free end subjecting to vertical pressures, is obtained. The approximate expression derives from the variational method. By comparing the precise numerical solution and the approximate solution of the cantilever beam with quality attached to the free end and subjecting to the vertical pressures, the conclusion of approximate linear relationship that is between the square of the natural frequency and axial force of the cantilever beam with quality attached to the free end subjecting to the vertical pressures is got. Through the comparing of theoretical results and finite element solutions, the difference between the approximate solution and the precise numerical solution is small, which can meet the requirements of accuracy on engineering. On this basis, as long as the natural frequencies of the structure at two load conditions are measured by experimental methods, elastic buckling load of the compressed beam can be identified. So the no damage test method to identify the elastic buckling load of the structures is given.
The Methods of Condition Monitoring for Key Components of Wind Turbine
Authors: Liu Xian Ming , Zhao Chun Hua , Zhong Xian You , Zhang Jin , Wan Shi Qing
Published: June 2012

The paper analyzed on failure mechanism of key components (blades, gearboxes) of wind turbine. Then, that introduced the development about the methods of condition monitoring of the key components. It also described that in recent years the development of methods with location of fault, fault diagnosis and failure distribution respectively. According to the present problems of condition monitoring of wind turbine, the text summed up the problems in four aspects for the future: research of the fault mechanism and failure criterion, vibration signal processing and the method of feature extraction research, study on coupling of wind turbine system, development of on-line monitoring systems.
Distribution of Sulfur Forms in Low Temperature Pyrolysis of Coal
Authors: Yao Qiu Xiang , Du Mei Li , Wang Shui Li , Liu Jing , Yang Jian Li , Shang Hai Tao
Published: June 2012

The distribution of sulfur forms in the products of low temperature pyrolysis of Carboniferous high sulfur coal from Northwest China was investigated. The typical method of Gray-King assay was used to carry out the low temperature pyrolysis experiments. GC-MS analysis was used to investigate the composition of sulfur compounds in the coal tar. The results show that sulfur mainly remained in the semi-coke and accounted for 80.97% of the total sulfur. Pyrites decomposed and transformed into sulfates and organic sulfur. 5 sulfur containing compounds were detected in the coal tar and they are dibenzothiophene, benzonaphthothiophene and their substituted homologs.
Investigation on Cooling System of High-Concentration Photovoltaic with Oscillating Heat Pipe
Authors: Geng Wen Guang , Gao Ling , Shao Min , Yuan Dong Ling , Li Xuan You
Published: June 2012

Cooling of concentration photovoltaic (CPV) cells with oscillating heat pipe was investigated numerically and experimentally. Based on Reynolds-averaged Navier-Stokes approach, a turbulent model was proposed in present work. Numerical study presented the temperature distribution under different heat flux and various outdoor conditions. CPV (with 12 suns concentration) system was experimentally studied, and the results show that the oscillating heat pipe begin operation at about 62°C, and CPV system could enhance electric power with a good cooling system under a high concentration light. The oscillating heat pipe cooling system, without air fan or pump, no power consumption, gives a uniform, reliable, simple and costless cooling method, oscillating heat pipe cooling is suitable for the high-CPV system.
Modelling of the Response of the Niutuozhen Low-Enthalpy Geothermal System in Hebei Province, China
Authors: Wang Shu Fang , Arnaldsson Andri , Axelsson Gudni , Pang Zhong He , Liu Jiu Rong
Published: June 2012

The Niutuozhen geothermal system, located in North China, is composed of the Jixian system dolomite reservoir and a Neogene sandstone reservoir. A three-dimensional model with 5437 elements and seven layers based on the geological and geothermal data was built using the AQUA3D package designed for solving flow and heat transport problems. Production history of forty five wells and pressure monitoring data from six wells were used for calibration. The calibrated model was then used to predict the geothermal system response of the geothermal field. The maximum predicted drawdown after 20 years of production without any reinjection ranged from 30 to 120 m in the north and south, respectively. The rate of drawdown was predicted to be kept at a lower level if 50% of the produced water was reinjected into the system. Cones of depression were predicted to gradually enlarge due to an increased production rate without reinjection, but were effectively limited and even diminished with a reinjection ratio of 50%. A maximum temperature decrease of 2.75°C was predicted to occur in production well A34, located near the reinjection well R3, for a production rate of 162 l/s with 50% reinjection. The maximum temperature decrease of 24.81°C was predicted to occur in the southern reinjection well R2. Prediction of temperature response indicated that the reinjection rate, the temperature of the reinjected water and the distance between the reinjection and production wells are the three factors affecting the reservoir temperature change. Reinjection is a indispensible measure for maintaining pressure of the reservoir. However, reservoir cooling induced by reinjection of the cold water should be considered carefully.
Seasonal Underground Storage of SGSHP System Design Based on Equilibrium Geothermal Temperature
Authors: Yu Tao , Liu Peng , Chu Guang Ming , Li Yong Feng
Published: June 2012

Constant geothermal temperature is necessary to the long-term efficient operation of the ground source heat pump. SGSHP (Solar-Ground Source Heat Pump) system adopts solar energy as assistant heat source to maintain the geothermal temperature in cold regions. A design method based on equilibrium geothermal temperature was illustrated with an example of a villa in Beijing, China. Flowchart and control strategy of the combined system were introduced. Average heat collection efficiency and necessary area of the solar collector were derived on the basis of energy balance equation. Geothermal temperature variation was also researched to test if the solar energy and geothermal energy were reasonably matched. Results show that the combined system can maintain a constant geothermal temperature if it is well designed. The solar-ground source heat pump system is efficient, reliable and energy-saving.
The Halting Process of Natural Circulation in Primary Circuit of Low Temperature Nuclear Heating Reactor
Authors: Zhang Xue Song , Ju Zhi Ping , Shi Jun Rui , Li Wei Zhe , Zhou Wen Ping
Published: June 2012

Fluctuation of security and flux, when natural circulation was halted in primary circuit of low temperature nuclear heating reactor by experiment during small break loss of coolant accident was studied. This is one of disadvantage aspect to such system. The results of this paper was Heated component won’t burn out while SBLOCA in lower cone in low temperature heating reactor. It was valuable suggestions on the development of commercial nuclear heating reactor.
Service Life Evaluation of Nuclear Power Plant Cable
Authors: Tian Feng , Ni Yan Rong , Su Wen
Published: June 2012

In this article we present our evaluation of the service life of the 6/10kv nuclear power plant electrical cables joint developed by our school and cooperative enterprise. The evaluation is based on the thermal life equation evolved from the Arrhenius equation: Log τ = a + b / T. Taking into account the effects of the manufacturing process on the service life of the cable, all of our samples are chosen directly from the factory finished product. The material of the first sample is cross-linked polyethylene, and the material of the second sample is low-smoke non-halogen cross-linked polyolefin. In our service life evaluation test design scheme, the test temperature is selected as 135 °C -180 °C, and the temperature range is 15 °C. The end-of-life elongation at break is by 220% for the first sample, and 140% for the second sample. In the article, we discuss the experiment process in more detail, and we keep accurate records of the relevant data. To improve the accuracy, we use the least squares method to process the test data. The results show that the service life of the cable can be up to 60 years and fully meet the design standards and user requirements.
Light Trapping Potential of Hexagonal Array Silicon Nanohole Structure for Solar Cell Application
Authors: Yahaya Nor Afifah , Yamada Noboru , Nakayama Tadachika
Published: June 2012

The reflectance of the hexagonal array silicon nanohole structure was systematically studied using various measurements and through simulations. It was found that the hexagonal array silicon nanohole can reduce the reflectance along the entire spectrum range by approximately 6%. It is suggested that the enhancement of the electric field intensity at short wavelength is mainly due to the large surface area provided by the nanohole structure, while multiple reflections occurring in the nanohole contribute to electric field enhancement in the long wavelength range. In addition, the simulation of a hexagonal array silicon nanohole coated with a thin layer of indium tin oxide (ITO) was carried out. The results show that reflectance is greatly decreased along nearly the entire spectrum range, except from 400 nm to 440 nm, and almost zero reflectance is achieved at wavelengths from 650 nm to 750 nm. The results provide a practical guideline to the design and fabrication of a low-reflectance, and as a consequence, a high-efficiency hexagonal array silicon nanohole solar cell.
A Literature Review of Tidal Power Generation with Coastal Reservoir
Authors: Kuang Cui Ping , Huang Hong Cheng , Pan Yi , Gu Jie
Published: June 2012

Tidal energy is a kind of new energy which is both renewable and pollution-free so that the tidal power generation is increasingly popular in the world. This paper is with respect to the current situation and prospects of development to the tidal power generation at home and abroad, from which it is realized that countries around the world set out the exploitation and utilization of tidal power generation as early as last century by carrying out a great quantity of research and practice, and building numerous tidal power generation stations. As we all know, water turbine generating units are absolutely necessary for tidal power generation. So this paper also refers to the water turbine generating units used in some tidal power generation stations and briefly presents their characteristics as well.