Numerical Modeling and Technico-Economic Analysis of a Hybrid Energy Production System for Self-Consumption: Case of Rural Area in the Comoros

This study aims to provide electricity to a remote village in the Union of Comoros that has been affected by energy problems for over 40 years. The study uses a 50 kW diesel generator, a 10 kW wind turbine, 1500 kW photovoltaic solar panels, a converter, and storage batteries as the proposed sources. The main objective of this study is to conduct a detailed analysis and optimization of a hybrid diesel and renewable energy system to meet the electricity demand of a remote area village of 800 to 1500 inhabitants located in the north of Ngazidja Island in Comoros. The study uses the Hybrid Optimization Model for Electric Renewable (HOMER) Pro to conduct simulations and optimize the analysis using meteorological data from Comoros. The results show that hybrid combination is more profitable in terms of margin on economic cost with a less expensive investment. With a diesel cost of $1/L, an average wind speed of 5.09 m/s and a solar irradiation value of 6.14 kWh/m2/day, the system works well with a proportion of renewable energy production of 99.44% with an emission quantity of 1311.407 kg/year. 99.2% of the production comes from renewable sources with an estimated energy surplus of 2,125,344 kWh/year with the cost of electricity (COE) estimated at $0.18/kWh, presenting a cost-effective alternative compared to current market rates. These results present better optimization of the used hybrid energy system, satisfying energy demand and reducing the environmental impact.

NUMERICAL SIMULATION ON THE WIND FIELD STRUCTURE OF A MOUNTAINOUS AREA BESIDE SOUTH CHINA SEA DURING THE LANDFALL OF TYPHOON MOLAVE

Leveraging the commercial CFD software FLUENT,the fine-scale three-dimensional wind structure over the Paiya Mountains on the Dapeng Peninsula near Shenzhen,a city on the seashore of South China Sea,during the landfall of Typhoon Molave has been simulated and analyzed.Through the study,a conceptual wind structure model for mountainous areas under strong wind condition is established and the following conclusions are obtained as follows:(1)FLUENT can reasonably simulate a three-dimensional wind structure over mountainous areas under strong wind conditions;(2)the kinetic effect of a mountain can intensify wind speed in the windward side of the mountain and the area over the mountain peak;and(3)in the leeward side of the mountain,wind speed is relatively lower with relatively stronger wind shear and turbulence.

Wind Tunnel Study of Multiple Factors Affecting Wind Erosion from Cropland in Agro-pastoral Area of Inner Mongolia,China

In this paper,the process of wind erosion on two kinds of soil from the agro-pastoral area of Inner Mongolia are studied using wind tunnel experiments,considering the wind speed,blown angle of wind and soil moisture content.The results showed that the modulus of soil wind erosion increases with an increase of wind speed.When the wind speed exceeds a critical value,the soil wind erosion suddenly increases.The critical speed for both kinds of soil is within the range of 7-8m·s-1.For a constant wind speed,the rate of soil wind erosion changes from increasing to falling at a critical soil slope.The critical slope of loam soil and sandy loam soil is 20° and 10°,respectively.Soil moisture content has a significant effect on wind erosion.Soil wind erosion of both soils decreases with an increase of the soil water content in two treatments,however,for treatment two,the increasing trends of wind erosion for two soils with the falling of soil water content are no significant,especially for the loam soil,and in the same soil water content,the wind erosion of two soils in treatment one is significantly higher than treatment two,this indicates reducing the disturbance of soil surface can evidently control the soil wind erosion.

Comparative Analysis of Wind break and Sand fixation Functions of Several Main Forage Plants in Minqin Desert Area

[Objective] The paper was to study wind-break and sand-fixation functions of forage plants in desert area. [Method]Based on the survey data of four major wind-break and sand-fixation plants( Haloxylon ammondendron,Artemisia arenaria,Nitraria tangutorum and Ephedra przewalskii) in Minqin desert area,the longitudinal section area and the sandpile volume of an individual plant and per unit area were calculated. The wind-break and sand-fixation functions of four major plant communities were comparatively analyzed. [Result] The wind-break functions of an individual plant( cluster) successively were N. tangutorum > H. ammondendron > A. arenaria and E. przewalskii; the sand-fixation functions of an individual plant( cluster) successively were N. tangutorum > E. przewalskii; the wind-break functions per unit area successively were A. arenaria > H. ammondendron > N. tangutorum > E. przewalskii; the sand-fixation functions per unit area were N. tangutorum > E. przewalskii; the wind-break and sand-fixation function per unit area were N. tangutorum > A. arenaria > H. ammondendron >E. przewalskii.[Conclusion]A. arenaria can be selected for only wind-break,and N. tangutorum can be chosen for only sand-fixation. If given consideration to both,N. tangutorum and A. arenaria must be selected.

Risk Assessment of Tropical Cyclones to Wind Farm Operation in Northern Costal Areas of Jiangsu Province

[Objectivel The study aimed to assess the risk of tropical cyclones to wind farm operation in northem costal areas of Jiangsu Province. [Metbod] Based on tropical cyclone data during 1951 -2011 from nine national basic weather stations as well as wind data during 2005 -2007 de- termined by six gradient wind measurement towers in northern costal areas of Jiangsu Province, the spatial and temporal distribution of tropical cy- clones influencing northern coastal areas of Jiangsu Province were discussed firstly, and then the possible effects of tropical cyclones on wind farms in the northern costal areas were assessed, finally some suggestions about type selection and parameter design of wind turbines were proposed. Restult Annual average number of tropical cyclones influencing northern coastal areas of Jiangsu Province was 1.7, and the first two kinds of tropical cyclones were dominant in quantity, accounting for about 73% for total quantity. The quantity of tropical cyclones bringing substantial economic benefits to wind farms accounted for 87.7% of total quantity, with annual average quantity of 1.5. Maximum wind speed appearing every 50 years did not exceed 37.5 m/s, in accord with the national Grade-Ill standard for safe operation of wind turbines. 2.1% -3.8% of turbulence intensity ei- genvalues at a height of 70 m exceeded the maximum anti-turbulence intensity designed by IEC （0.16）, and it is suggested that anti-turbulence in- tensity parameter of wind turbines in northem costal areas of East China should be changed to 0.31 -0.41. [ Conclusion] The research could provide scientific references for design and choice of wind turbines as well as operation and management of wind farms in the study region in future.

Numerical Tools Dedicated to Wind Engineering in Large Urban Area

This paper presents a global methodology to compute wind flow in complex urban areas in order to assess wind pedestrian comfort, wind energy, wind safety or natural ventilation potential. The numerical tool presented here is composed of a CFD soft-ware suite covering both regional scale (20 km) and urban scale (1km), and able to model the wind in any complex terrains and in large urban environments. Examples are presented in the paper in order to show the advantages of the methodology for urban designers.

The Influence of Radial Area Variation on Wind Turbines to the Axial Induction Factor

Improvements in the aerodynamic design will lead to more efficiency of wind turbines and higher power production. In the present study, a 3D parametric gas turbine blade geometry building code, 3DBGB, has been modified in order to include wind turbine design capabilities. This approach enables greater flexibility of the design along with the ability to design more complex geometries with relative ease. The NREL NASA Phase VI wind turbine was considered as a test case for validation and as a baseline by which modified designs could be compared. The design parameters were translated into 3DBGB input to create a 3D model of the wind turbine which can also be imported into any CAD program. Design modifications included replacing the airfoil section and modifying the thickness to chord ratio as a function of span. These models were imported into a high-fidelity CFD package, Fine/TURBO by NUMECA. Fine/TURBO is a specialized CFD platform for turbo-machinery analysis. A code-geomturbo was used to convert the 3D model of the wind turbine into the native format used to define geometries in the Fine/TURBO meshing tool, AutoGrid. The CFD results were post processed using a 3D force analysis code. The radial force variations were found to play a measurable role in the performance of wind turbine blades. The radial component of the blade surface area as it varies in span is the dominant contributor of the radial forces. Through the radial momentum equation, this radial force variation is responsible for creating the streamline curvature that leads to the expansion of the streamtube (slipstream) that is responsible for slowing the wind velocity ahead of the wind turbine leading edge, which is quantified as the axial induction factor. These same radial forces also play a role in changing the slipstream for propellers. Through the design modifications, simulated with CFD and post-processed appropriately, this connection with the radial component of area to the radial forces to the axial induction factor, and finally the wind turbine power is demonstrated. The results from the CFD analysis and 3D force analysis are presented. For the case presented, the power increases by 5.6% due to changes in airfoil thickness only.

Abnormality of the monsoon wind in the sea area along the southeasterncoast of China and the response of the northern areaof the South China Sea during the ENSO events

-Variations of monsoon wind field in the sea area along the southeastern coast of China during the ENSO events and its influence on the sea level and sea surface temperature (SST) are explored mainly on the basis of the data of monthly mean wind at 850 hPa and five coastal stations during 1973-1987. The results from the analyses of the data and theoretical estimation show that the southwest wind anomalies appeared in the study area during the events, and northeast wind anomalies occurred in general before the events. With the coastline of the area being parallel basically to the direction of the wind, an Ekman transport will result in an accumulation of the water near the coast or a departure of the water from the coast. As a result , the sea level and SST there will be affected markedly. During the events, southwest wind will intensify in the summer, and northeast wind will weaken in the winter. Their total effect is that a large negative anomaly of the sea level and SST will occur. The estimations indicate that the monsoon wind is stronger in the summer and weaker in the winter than the normal by 1-1. 5 m/s during the events, and this anomaly will cause a decrease of the sea level by 7-11 cm . Changes of the wind field, therefore, is mainly responsible for a large negative anomalies of the sea level and SST there during the ENSO events.

Particle Size of Barchan Dune in Hexi Desert Area and Its Relationship with Wind Speed

[ Objective ] The paper was to study the particle size characteristics of barchan dune and its formation mechanism in Hexi desert area d Gansu. [ Method] Through particle size measurement and wind speed flow field observation d dune, the particle size differences of various sampling plots and various parts of dune were analyzed using analysis of variance, and the relationship between particle size and wind speed was analyzed using correlation coefficient method. [ Result] （ 1 ） Barehan dune and barehan chains in Hexi desert area of Gansu were mainly consisted of fine sands and medium sands at the depth of 0 -5 cm： the sand particle in Gulang desert area was fine, which had significant difference with that in Jinchang, Linze, Jinta and Minqin desert areas. （2） Medium sands gradually increased from the bottom of windward slope to the dune peak in both barchan dune and barchan chain. On the windward slope of barehan dune, fine sands gradual- ly increased from the middle to both sides, while coarse sands and medium sands gradually decreased. On the windward slope of barehan chain, fine sands first de- creased then increased from the middle to NE side, but first increased then decreased from the middle to SW side. （3） In terma of particle size, there were great variations between fine sands and coarse sands ; for dune parts, there were great variations between dune peak and leewant slope toe; for dune types, the variation of fine sands in various parts of barchan chain was greater than that of barchan dune, while differentiation degree of medium sands and fine sands was greater than that of barchan dune. The particle size of fine sands was positively correlated with wind speed, and that of medium sands was negatively correlated with wind speed. [ Conclusion] The formation environment of particle size of berehan dune mainly included sand source and dynmnic source, and wind speed was the dynamic source for particle size distribution of barchan dune.

基于综合优属度的大风区高速铁路线路方案优选研究

为了应对西部路网扩张过程中必须面临的大风环境高铁建造问题,从问题的本源出发,研究选线设计与大风环境的耦合关系,建立科学的决策模型成为实现高速铁路高质量建设的关键内容。通过分析大风区高速铁路线路方案设计的主要影响因素并参考选线原则,从工程技术、生态环境、防风工程和社会效益4个方面选取22项指标,建立大风区高速铁路线路方案优选的多层次指标体系。采用三角模糊数对定性指标量化后,引入最佳去模糊性能值的方法将其转化为精确数,并融合粗糙集理论中的属性约简算法与信息熵理论,根据属性重要度将冗余或不重要的属性去除,实现初选指标的筛选。为使结果既能反映决策者的主观经验,又能反映指标数据的客观真实性,同时兼顾数据的变异和相互影响程度,分别采用G2法和CRITIC法进行主、客观赋权,并引入最优卡方距离的思想计算最终权重。最后,统筹考虑距离相似性和几何相似性维度,采用靶心距确定距离优属度以及与集合曲线趋势变化的趋同程度确定几何优属度,建立基于综合优属度的大风区高速铁路线路方案决策模型,并结合工程实例对模型进行验证。结果表明,基于本模型的大风区高速铁路方案的决策结果与工程实际具有较好的一致性,验证了模型的可靠性和适用性,为大风区高铁线路方案优化设计提供一定的理论支持。

海温异常对长江流域夏季典型旱涝的影响研究

为研究长江流域夏季旱涝特征及其与海温异常之间的关联性,基于中国326个气象站降水量、NCEP/NCAR再分析资料等,采用合成分析、EOF分解等方法,分析了长江流域夏季典型旱涝年的降水分布、同期大气环流及前期海温特征,并以2018年为例,初步揭示了2018年前期海温异常对大气环流的可能影响。结果表明:①长江流域夏季典型旱年,仅嘉陵江和岷沱江会表现出局部偏涝,全国为典型的Ⅰ类雨型,多雨区位于黄河流域及以北地区。前期冬季赤道太平洋表现出类拉尼娜的东冷西暖分布,同时黑潮区海温偏低,西风漂流区海温偏暖。受多海域协同作用,同期欧亚环流场上自西北向东南呈现出“+-+”三极型分布,东亚地区为自北向南“-+-”的EAP负位相。长江流域典型涝年,全国多为典型的Ⅱ类和Ⅲ类雨型,环流及海温呈现出相反特征。②2018年为典型的长江中下游偏旱年,仅在岷沱江降水偏多近3成,为历史第4多,与长江流域夏季降水的主模态正位相类似,解释方差达24%。③2018年前冬出现弱拉尼娜、春末夏初西风漂流区异常偏暖、NAT异常正位相,三者共同作用,使得东亚副热带西风急流偏北,东亚沿岸出现EAP负位相,大陆热低压明显偏强,东亚夏季风为1961年以来最强,同时副高脊线最北,造成夏季降水主雨带北推至华北、西北地区,岷沱江、嘉陵江异常多,而长江中下游异常少,为典型的Ⅰ类雨型。研究成果可为长江流域旱涝预测、水资源调度提供参考。

Industrial Arrangement of Large-scale,Non-grid-connected Wind Power Industrial Zones in Coastal Areas of China

Constructing an industrial system for a large-scale,non-grid-connected wind power industry is a key step towards the diverse utilization of wind power.However,wind power exploitation is not only a technical challenge but an industrial problem as well.The objective of this study is to introduce a concept of large-scale,non-grid-connected wind power(LSNGCWP) industrial zones and establish an evaluation model to assess their industrial arrangement.The data of wind energy,industry,nature resources and socio-economy were collected in this study.Using spatial overlay analysis of geographic information system,this study proposes a spatial arrangement of the LSNGCWP indus-trial zones in the coastal areas of China,which could be summarized as the 'one line and three circles' structure,which will contribute to the optimization of the industrial structure,advance the wind power technology,coordinate the multi-industrial cooperation,and upgrade the industrial transformation of China's coastal areas.

大风区高速铁路路基双侧挡风墙周围沙粒沉积数值模拟研究

兰新高速铁路横穿多个大风区,对其安全运营造成严重影响。为降低强风对线路的危害,在大风区修筑大量防风构筑物,其中以路基挡风墙最为常见,挡风墙降低了风害的影响,但是带来严重的线路积沙问题。通过数值模拟研究不同风速下路基双侧挡风墙周围的流场特征,利用风产生的壁面剪切应力与沙粒剪切应力的比值确定地表沙粒沉积与侵蚀类型。研究发现,气流在两道挡风墙之间分别形成一个顺时针涡流和一个逆时针涡流,在第二道挡风墙背风侧形成一个顺时针大涡,随着来流风速增大,漩涡尺寸和涡流强度均在增大;由于涡流的存在,部分沙粒被卷走,路堤背风坡附近以及路基面上的沙粒沉积显著减少,当来流风速为24、30 m/s时,南北侧线路道床面均出现沙粒反向侵蚀;单双侧挡风墙的积沙规律对比结果表明,设置双侧挡风墙时,线路积沙显著减少。研究揭示了大风区铁路双侧挡风墙周围路基面上的沙粒沉积规律,对未来风区铁路的防护建设具有指导意义。

Theoretical Study of Wind Turbine Model with a New Concept on Swept Area

Commercially available wind-turbines are optimized to operate at certain wind velocity, known as rated wind velocity. For other values of wind velocity, it has different output which is lower than the rated output of the wind plant. Wind mill can be designed to provide maximum power output at different wind velocities through modification of swept area to match with the wind speed available at the moment. This can result in higher power output at all the velocities except that at rated wind speed because of limitation of generator. This results in increased utilization of generation capacity of wind mill compared to its commercially designed counterpart. A theoretical simulation has been done to prove a new concept about swept area of wind turbine blade which results in a significant increase in the power output through the year. Simulation results of power extracted through normal wind blade design and new concept are studied and compared. The findings of the study are presented in graphical and tabular form. Study establishes that there can be a significant gain in the power output with the new concept.

基于节段模型测力方法的塔式起重机风荷载特性研究

塔式起重机被广泛应用于铁道工程和土木工程施工过程,属于高耸结构体系,风荷载是塔式起重机结构设计的控制性荷载。为完善《塔式起重机设计规范》(GB/T 13752—2017)和《建筑结构荷载规范》(GB 50009—2012)中的塔式起重机斜风向设计风荷载计算方法,解决风向、吊臂、平衡臂位置等因素对塔式起重机遮挡和干扰引起的设计风荷载计算问题。选取平头塔式起重机为研究对象,对塔身、吊臂、平衡臂进行多工况的节段模型测力风洞试验,研究湍流强度、节段干扰和遮挡等因素对塔式起重机节段风荷载特性的影响规律,研究不同风向下节段阻力系数分布规律,对比标准化阻力系数与当前主要规范的异同,进而探讨节段斜风向标准化阻力系数计算方法。研究结果表明湍流强度对节段阻力系数影响较小,可忽略,而平衡臂和吊臂相邻节段的干扰会减小测试节段的阻力系数;在斜风向下,由于吊臂和平衡臂之间存在相邻节段干扰,国内外规范方法的计算值均会大于干扰工况的节段风洞试验值;当前主要国家规范规定的垂直风向塔身、吊臂、平衡臂阻力系数与风洞试验测得的阻力系数值较为接近,基于风洞试验结果给出典型风向的塔式起重机各节段的风荷载系数取值可用于结构设计;基于风洞试验测试结果推导的塔式起重机斜风向风荷载计算方法具有较好的拟合效果。研究成果可推荐相关工程应用,可为相关规范的修改或补充提供参考。

Use of Augmented Reality Methods to Support Legal Conflicts in the Planning Process for Wind Turbines Using the Example of the Landscape Conservation Area “Eulenkopf and Surroundings”

The world’s growing energy demand poses a serious problem. At the same time fossil fuels are finite, which we must work against. Therefore, the Federal Government of Germany has set itself the goal to push forward the use of renewable energy in order to completely do without the generation of nuclear energy by 2023. There are, however, no specific guidelines from the European Directive on the promotion of electricity from renewable energy sources for the internal electricity market regarding how high each share of the different production method should be and, above all, which specific aim should be achieved by the share of wind energy. Nevertheless, it presents a crucial step toward a nuclear phaseout and a concomitant change of course of the Federal Government of Germany in the spring of 2011 regarding the expansion of renewable energy, taking the nuclear catastrophe in Fukushima into account. Using new legal planning approaches, also including the area of Rhineland-Palatinate, opportunities should be provided to make previously protected land available for setting up facilities for the generation of renewable energy. However, it is important to examine the legal situation regarding the installation of these kinds of constructions more detailed, as no general statements can be made. This will be illustrated using the example of the landscape conservation area “Eulenkopf and surrounding area” in the district of Kaiserslautern. The stated goal of the Social Democrat/Green coalition of the federal state government of Rhineland-Palatinate is to considerably expand the generation of electricity from renewable energy sources so that by 2030 at least the entire electricity demand can be covered by those. Due to the enormous potential of wind power, it is therefore necessary to quintuple its share of electricity generation by 2020, compared to 2011 numbers. In order to achieve the desired political objectives, by 2030 the number of turbines has to be increased to around 2650, representing a capacity of 7500 MW. This increase gives reason for boundary conditions to manage the generation of wind energy to be adjusted. This is intended to facilitate management and simultaneously minimise negative effects, such as the “sprawling” of wind turbines.

基于数值模拟的近海广阔区域办公区风环境研究与改善

近海广阔区域由于缺乏地形遮挡,海洋气流对建筑区域影响显著,导致风速较大,进而引起人员不适,当强/台风来临时还可能会引起人员伤亡。以暖温带东亚季风区大陆性气候、近海广阔区域——胶东半岛的一办公区为例,利用CFD(计算流体力学)软件对办公区的风环境进行研究,以目标区域空旷平坦地面10年一遇10 m高度处10 min平均的风速观测数据为依据,风向以目标区域冬季季风主导方向为主,获得建筑区域的风速云图,确定不利风速区域。进一步,采用10年一遇10 m高度处3 s阵风风速进行极端风速下的研究,结合地形环境,提出风场环境改善方案,定量与定性地分析改善后的风场环境。研究结果可为近海广阔区域风环境的研究与改善提供依据。

基于CFD的LNG储罐瞬时大风环境数值模拟研究

为分析不同大风风速下储罐迎风侧和背风侧压力分布情况和风场特点,采用k-ε湍流模型,建立液化天然气(LNG)储罐区瞬时大风环境模型。利用计算流体动力学(CFD)软件Fluent对LNG储罐风环境进行模拟,利用软件分析模块生成储罐压力云图和风速矢量图。研究结果表明:LNG储罐在迎风侧承受压力高于背风侧,压力呈现对称分布;储罐前端与两侧易产生气体漩涡,但总体速度曲线较为规律,无混乱复杂的速度曲线。研究结果可为LNG场站抗灾韧性增强、极端大风天气应急疏散路径规划等多方面提供理论参考,对LNG储罐区安全建设具有重要指导意义。

汽车发动机舱盖前密封条处口哨声抑制方法的研究

某新能源车型开发过程中,在高速100km/h以上时,驾驶室明显感知到发动机舱盖前部有口哨般啸叫声。通过风洞和道路验证,表明发动机舱盖前部的造型设计、前保格栅的通风面积、发动机舱盖前部密封空腔的大小,对该啸叫声有较大影响。本文以此为背景,对啸叫声的发声机理进行深入的研究,并设计多个方案进行验证,最终通过减小发动机舱盖前部密封空腔面积解决了该啸叫声。同时总结了抑制啸叫声的方法,为后续新能源车型的风噪开发提供了参考。

槽式太阳能阵列挡风增速效果数值模拟

采用开源计算流体力学软件OpenFOAM中的Simple求解器对流场进行数值模拟,研究5.00 m/s风速下槽式太阳能阵列挡风墙挡风效果。对由槽式太阳能阵列组成的6个不同高度的挡风墙对整体流场速度的影响以及不同高度挡风墙背风侧30,60,90 m处的速度进行了分析。研究发现,当气流通过挡风墙时,低于墙高的位置速度大幅衰减,而高于墙高的位置开始加速,存在明显的分区作用。当气流流过挡风墙后,会在其后形成明显的速度衰减区,其面积和延伸与挡风墙的高度正相关。在挡风墙背风侧较远处,高于墙高的气流开始减速,低于墙高的气流开始加速,并随着距离的增加风速逐渐趋于平稳。