The Design of Stall-Regulated Wind Turbine Blade for a Maximum Annual Energy Output and Minimum Cost of Energy Based on a Specific Wind Statistic

The design of a stall-regulated wind turbine to achieve a maximum annual energy output is still a formidable task for engineers. The design could be carried out using an average wind speed together with a standard statistical distribution such as a Weibull with k = 2.0. In this study a more elaborated design will be attempted by also considering the statistical bias as a design criterion. The wind data used in this study were collected from three areas of the Lamtakong weather station in Nakhonratchasima Provice, the Khaokoh weather station in Phetchaboon and the Sirindhorn dam weather station in Ubonratchathani, Thailand. The objective is to design a best aerodynamic configurations for the blade (chord, twist and pitch) using the same airfoil as that of NREL Phase VI wind turbine. Such design is carried out at a design wind speed point. Wind turbine blades were optimized for both maximum annual energy production and minimum cost of energy using a method that take into account aerodynamic and structural considerations. The work will be carried out by the program “SuWiTStat” which was developed by the authors and based on BEM Theory (Blade Element Momentum). Another side issue is the credibility of the Weibull statistic in representing the real wind measurement. This study uses a regression analysis to determine this issue.

LVDC: An Efficient Energy Solution for On-Grid Photovoltaic Applications

In this paper some photovoltaic, PV, conversion chains architectures for on-grid applications have been proposed and the advantage of the direct use of a Low Voltage Direct Current (LVDC) bus for the DC loads has been shown. The evaluation of the efficiency of the proposed chains compared to the classical one was performed. It is shown that LVDC use instead of standard AC plugs, in numerous applications, is promising in future. The registered annual saved energy can exceed 25% of the PV generated energy. This important rate, the need of better services at lower economic cost and environmental burden will incite to make reflection about industry and supplies’ future standards.

Three-year Variations of Water, Energy and CO_2 Fluxes of Cropland and Degraded Grassland Surfaces in a Semi-arid Area of Northeastern China

Based on 3 years （2003-05） of the eddy covariance （EC） observations on degraded grassland and cropland surfaces in a semi-arid area of Tongyu （44°25′N, 122°52′E, 184 m a.s.1.）, Northeast China, seasonal and annual variations of water, energy and CO2 fluxes have been investigated. The soil moisture in the thin soil layer （at 0.05, 0.10 and 0.20 m） clearly indicates the pronounced annual wet-dry cycle; the annual cycle is divided into the wet （growing season） and dry seasons （non-growing season）. During the growing season （from May to September）, the sensible and latent heat fluxes showed a linear dependence on the global solar radiation. However, in the non-growing season, the latent heat flux was always less than 50 W m^-2, while the available energy was dissipated as sensible, rather than latent heat flux. During the growing season in 2003-05, the daily average sensible and latent heat fluxes were larger on the cropland surface than on the degraded grassland surface. The cropland ecosystem absorbed more CO2 than the degraded grassland ecosystem in the growing season in 2003-05. The total evapotranspiration on the cropland was more than the total precipitation, while the total evapotranspiration on the degraded grassland was almost the same as the total annual precipitation in the growing season. The soil moisture had a good correlation with the rainfall in the growing season. Precipitation in the growing season is an important factor on the water and carbon budget in the semi-arid area.

The variability of eddy ki/netic energy in the South China Sea deduced from satellite altimeter data

We used fifteen years （1993-2007） of altimetric data, combined from different missions （ERS-1/2, TOPEX/Poseidon, Jason-l, and Envisat）, to analyze the variability of the eddy kinetic energy （EKE） in the South China Sea （SCS）. We found that the EKE ranged from 64 cm2/s2 to 1 390 cm2/s2 with a mean value of 314 cm2/s2. The highest EKE center was observed to the east of Vietnam （with a mean value of 509 cm2/s2） and the second highest EKE region Was located to the southwest of Taiwan Island （with a mean value of 319 cm2/s2）. We also found that the EKE structure is the consequence of the superposition of different variability components. First, interannual variability is important in the SCS. Spectral analysis of the EKE interannual signal （IA-EKE） shows that the main periodicities of the IA-EKE to the east of Vietuam, to the southwest of Taiwan Island, and in the SCS are 3.75, 1.87, and 3.75 years, respectively. It is to the south of Taiwan Island that the IA-EKE signal has the most obvious impact on EKE variability. In addition, the IA-EKE exhibit different trends in different regions. An obvious positive trend is observed along the east coast of Vietnam, while a negative trend is found to the southwest of Taiwan Island and in the east basin of Vietnam. Correlation analysis shows that the IA-EKE has an obvious negative correlation with the SSTA in Nifio3 （5°S-5°N, 90°W-150°W）. E1 Nifio-Southem Oscillation （ENSO） affects the 1A-EKE variability in the SCS through an atmospheric bridge--wind stress curl over the SCS. Second, the seasonal cycle is the most obvious timescale affecting EKE variability. The locations of the most remarkable EKE seasonal variabilities in the SCS are to the east of Vietnam, to the southwest of Taiwan, and to the west of Philippines. To the east of Vietnam, the seasonal cycle is the dominant mechanism controlling EKE variability, which is attributed primarily to the annual cycle there of wind stress curl. In this area, the maximum EKE is observed in autumn. To the southwest of Taiwan Island, the EKE is enlarged by the stronger SCS circulation, which is caused by the intrusion branch from the Kuroshio in winter. Finally, intra-annual and mesoscale variability, although less important than the former, cannot be neglected. The most obvious intra-annual and mesoscale variability, which may be the result of baroclinic instability of the background flow, are observed to the southwest of Taiwan Island. Sporadic events can have an important effect on EKE variability.

A seasonal grade division of the global offshore wind energy resource

Under the background of energy crisis, the development of renewable energy will significantly alleviate the energy and environmental crisis. On the basis of the European Centre for Medium-Range Weather Forecasts（ECMWF）interim reanalysis（ERA-interim） wind data, the annual and seasonal grade divisions of the global offshore wind energy are investigated. The results show that the annual mean offshore wind energy has great potential. The wind energy over the westerly oceans of the Northern and Southern Hemispheres is graded as Class 7（the highest）, whereas that over most of the mid-low latitude oceans are higher than Class 4. The wind energy over the Arctic Ocean（Class 4） is more optimistic than the traditional evaluations. Seasonally, the westerly oceans of the Northern Hemisphere with a Class 7 wind energy are found to be largest in January, followed by April and October, and smallest in July. The area of the Class 7 wind energy over the westerly oceans of the Southern Hemisphere are found to be largest in July and slightly smaller in the other months. In July, the wind energy over the Arabian Sea and the Bay of Bengal is graded as Class 7, which is obviously richer than that in other months. It is shown that in this data set in April and October, the majority of the northern Indian Ocean are regions of indigent wind energy resource.

Design and Optimization of a Hybrid Energy System for Decentralized Heating

The performances of a hybrid energy system for decentralized heating are investigated.The proposed energy system consists of a solar collector,an air-source heat pump,a gas-fired boiler and a hot water tank.A mathematical model is developed to predict the operating characteristics of the system.The simulation results are compared with experimental data.Such a comparison indicates that the model accuracy is sufficient.The influence of the flat plate solar collector area on the economic and energy efficiency of such system is also evaluated through numerical simulations.Finally,this system is optimized using the method of orthogonal design.The results clearly demonstrate that the solar-heat pump-gas combined system is more convenient and efficient than the simple gas system and the heat pump-gas combined system,whereas it is less convenient but more efficient than the solarassisted gas system.

Yield Production and Energy Budget of Traditional Agricultural Crops in Garhwal Himalaya

The yield production and energy budget of agroecosystem was carried out at three different climatic regions, i.e., tropical, sub-tropical, and temperate in Garhwal Himalaya, India. The total human population was the highest （1 140） in tropical region, followed by 464 in temperate region, and 374 in sub-tropical region. Livestock population had also a similar trend with human population in each climatic region, which was 870, 290, and 188 in the tropical, temperate, and sub-tropical regions, respectively, in winter season, the crop production was the highest （2 332 kg hat yr-l） for Triticum aestivum in tropical region followed by 1 716 kg ha^-1 yr^-1 in sub-tropical region, and 1 473 kg ha^-1 yr^-1 in temperate region. The associated crops were Itordeurn vulgate, Brassica caml ＇stris, and Pisum sativa. However, in summer season, the most contributing crop was Oryza sativa, which had also the highest production in tropical region followed by sub-tropical region, and temperate region, i.e., 1 160, 1096, and 1 076 kg ha^-1 yr^-1, respectively. Other growing crops were Elusine coracana, Vigna mugo, Glycine soja, and Echnochlolafrumentaceae. Brassiea rugosa was the only crop grown in tropical region between the period of winter and summer season. The total root production of crops in each climatic region was the highest in tropical region （1 846.2 kg ha^-1 yr^-1）, followed by temperate region （1 841.5 kg ha^-1 yr^-1） and sub-tropical region （1442.5 kg ha^-1 yr^-1）. However, shoot components of crops were 20 241.5, 17 847.0, and 1 188.3 kg ha^-1 yr^-1, which recorded parallel to root in each climatic region. The root and shoot components of weed decreased with increasing altitudes, which were 105.39 and 1150.5 kg ha^-1 yr^-1 in tropical region, 94.55 and 1147.5 kg ha^-1 yr^-1 in sub-tropical region, and 73.33 and 871.5 kg ha^-1 yr^-1 in temperate region for root and shoot, respectively. In the energy inputs, the most contribution was of compost in each climatic region. Among the region, the highest input of compost was in temperate region followed by sub-tropical, and the lowest in temperate region. The fertilizer input was only recorded from tropical region because of its close connection with market and easy accessibility to the farmer compared to subropical and temperate regions. The energy input ranged from 0.39×10^5 to 0.44× 10^5 MJ ha^-1 （human labour）, 0.84× 10^5 to 1.09× 10^5 MJ ha^-1 （bullock labour）, 0.36×10^5 to 0.45×10^5 MJ ha^-1 （seed）, 16.65 × 10^5 to 32.65 ×10^5 MJ ha^-1 （compost）, while output ranged from 8.44 × 10^5 to 11.01 × 10^5 MJ ha^-1 （agronomic yield）, and 14.22× 10^5 to 19.35 ×10^5 MJ ha^-1 （crop-residue）. The total input was the highest in temperate region, followed by subtropical and tropical region, and the highest output was in tropical region and the lowest in sub-tropical region.

Assessment of PV Shading Device on Building Energy Consumption Taking into Account Site Layout

This paper presents the results of a combined study of building energy consumption and the electricity production from PV modules integrated into a shading device, taking account of different site layouts. Various combinations of surrounding building configurations and the tilt angles of the shading device （that determines the PV module orientation） are examined.

An Advanced Simple Method for Generating Synthetic Average Instant Hourly Solar Energy

The main objective of this study is to generate accurate synthetic hourly solar radiation data by using an easily accessible open source data.In this regard,a new approach is proposed for estimation of synthetic hourly global solar radiation during the day by utilizing only annual solar energy data.First time in literature,a model has been developed for prediction hourly and daily solar radiation based on annual solar energy parameter in this study.Parameters of the model were generated and tested for Turkey and one of them was presented as a case study within this paper.Long term measured hourly horizontal solar irradiance data from a network of Turkish meteorological stations was used to calibrate the model function.The predictions are compared with the solar data available in literature for Turkey.The advanced simple new model is utilized in open source computer program and has the potential to be adapted to other countries.

热泵精馏耦合吸收处理含盐氨水

针对含盐氨水的回收与处理,利用蒸发除盐、精馏脱氨并耦合吸收制备一定浓度的氨水。采用一系列节能技术对蒸发和精馏进行计算优化,即双效蒸发与塔顶蒸汽直接压缩热泵精馏耦合吸收工艺(SchemeⅠ)、热泵蒸发与塔顶蒸汽直接压缩热泵精馏耦合吸收工艺(SchemeⅡ)和热泵蒸发与塔底闪蒸再压缩热泵精馏耦合吸收工艺(SchemeⅢ)。选用ELECNRTL电解质模型计算物系的热力学数据和相平衡数据,并以年总费用、综合能耗和热力学效率等作为工艺评价指标,对提出的以上3种处理工艺进行模拟与优化。研究结果表明,与SchemeⅠ相比,SchemeⅡ和SchemeⅢ可分别节省年总费用22.18%和31.66%;节约能耗47.56%和57.87%;而热力学效率则分别提高了8.59%和2.28%。显然,SchemeⅢ在年总费用与能耗方面更具优势,SchemeⅡ在热力学效率方面更具优势。

基于正交试验法的太阳能复合热水系统优化

为降低生活热水能耗,实现空气源热泵辅助太阳能供热水系统的高效节能运行,选取济南市某高校学生宿舍空气源热泵辅助太阳能供热水系统作为研究对象,利用瞬时系统模拟软件搭建了系统仿真模型,并采用无交互作用的正交试验法,分别以全年系统性能系数和太阳能保证率为优化目标,优化了太阳能集热器面积、集热器倾角、热泵制热功率及水箱容积,并分析其结果的经济性和节能性。结果表明:当以系统性能系数为优化目标时,最优组合中集热器面积为390 m^(2)、集热器倾角为42°、热泵制热功率为50 kW、水箱容积为23.94 m3,而动态费用年值为7.38万元,较天然气系统年节省标煤为17.12 tce;当以太阳能保证率为优化目标时,最优组合中集热器面积为342 m^(2)、集热器倾角为44°、热泵制热功率为35.5 kW、水箱容积为20.58 m3,而动态费用年值为6.56万元,较天然气系统年节省标煤为16.63 tce。

基于风机式激光测风雷达的风机功率特性曲线测试方法

通过风机式激光测风雷达(NML)测试风机功率特性曲线(PPM),对比分析风机式NML和测风塔的结果差异,评估两种方法在发电量计算中的不确定性。结果表明,风机式NML与测风塔的风速测量一致,相关系数可达0.994,拟合的斜率和截距分别为0.979和0.084;风机式NML的测试数据在功率特性曲线的散点分布图中更集中;发电量评估结果表明,NML比测风塔高估发电量1.73%。不同风向扇区的研究结果表明,测风塔在不同风向下处于风机的不同方位,NML随风机机舱的偏航始终测量风机正前方风速,与风向保持一致,因此散点更为集中。风机式NML对PPM测试的不确定度更低,对风机叶轮上平均风速更具有代表性,具有一定的研究意义与实际应用价值。

家用空调器产品监督检验中常见不合格项目解析

制冷量、制冷消耗功率、全年能源消耗效率(APF)和制冷季节能源消耗效率(SEER)、接地措施、连续骚扰(端子电压)这五个项目是家用空气调节器产品在监督检验中常见的不合格项目,本文通过列举具体案例,从标准要求和实测数据等方面,重点分析了导致不合格产生的客观及主观原因,并给出了相应的整改方案,为企业提升认识、完善设计、加强质控、规范制造提供了有效的改进建议,助力企业生产出符合国家标准要求的合格产品。

考虑时段校核和季节性储能的多区互联电力系统年度发电计划

随着新能源发电量占比的提高,新能源发电量季节性波动引起的年度电力电量平衡问题更加明显。建立年度发电计划模型,提出一种典型时段校核方法;在年度发电计划制定的过程中引入季节性储能设备,建立季节性储氢模型和考虑水头位置的季节性抽水蓄能线性化模型;为了应对新能源出力的不确定性,提出考虑时段校核和季节性储能的年度发电计划三阶段建模方法。算例结果验证了所提模型的有效性。

云储能模式下分布式用户虚拟储能需求评估

采用分布式储能技术可以改变能量的时空分布,提高配电网消纳分布式能源的灵活性。传统储能模式下储能成本过高、储能资源利用率低,而云储能是一种能够响应分布式储能需求的新型商业模式。文章考虑负荷、可再生能源出力、分时电价以及虚拟储能价格等影响用户虚拟储能需求的因素,建立了云储能模式下分布式用户虚拟储能需求配置优化模型。为验证该模型的有效性,选取社区内14个典型用户为分析对象。算例分析表明,与传统储能模式相比,云储能模式下用户的虚拟储能容量及功率需求分别降低了18.2%和7.1%,年化成本降低了4.12%,储能资源利用率提升了8.12%。因此,云储能模式具有很好的应用前景。

基于PSO-MSVR的太阳能耦合土壤源热泵系统优化配置

为了优化太阳能耦合土壤源热泵系统(SGSHPS)的配置,以沈阳地区办公建筑为例,基于TRNSYS平台建立了不同运行模式的SGSHPS模型,对比分析不同模式下系统运行30 a后土壤温度不平衡率和系统总能耗;以并联过渡季蓄热模式为对象,对不同的太阳能集热系统和地埋管换热器组合方式进行模拟;在保证系统稳定的前提下,以动态费用年值最低为目标,优化太阳能集热器面积和地埋管换热器钻孔数的配置方式;引入粒子群优化-多输出支持向量机回归(PSO-MSVR)算法,使用PSO算法生成MSVR模型参数并寻找最优值。结果表明:与采用传统热平衡法确定的配置方式相比,优化后运行30 a的系统能耗降低379522 kW,节能11.2%,费用年值降低61863元,土壤温度仅上升0.73 K;对于不同的太阳能集热器和地埋管换热器造价,优化后费用年值相较优化前仍有不同程度的节省,且土壤温度均未有较大偏移。

高效制冷站在某汽车工厂涂装车间的应用研究

从高效制冷站的基本概念及设计理念出发,以高效供需匹配为导向,给出了高效制冷站的设计要点及其在汽车工厂涂装车间的应用案例。案例实际运行数据表明,该制冷站的全年运行平均能效比(EER)达到6.5,远高于T/CECS 1100—2022《高效空调制冷机房评价标准》一级要求,实现节能50%以上。

双馈型风电机组传动链降载控制技术研究与仿真

为定量研究双馈型风力发电机组传动链的扭振控制,提出了一种基于卡尔曼滤波的反馈控制策略,并通过仿真计算的方式对比了传动链扭振的控制效果。以7.0 MW双馈型风力发电机组传动链为研究对象,采用卡尔曼滤波估计传动链扭振角度,并以低速轴扭振速度估计值为参考设计了发电机附加电磁转矩作用于风电机组转矩控制,与虚拟阻尼控制、无阻尼控制进行了20年全生命周期内的载荷与发电量计算对比。结果表明:经过卡尔曼滤波估计的低速轴扭角与实际值的相关性可以达到0.99;基于卡尔曼滤波的反馈控制分别与虚拟阻尼控制、无阻尼控制的关键差异为,传动链低速轴等效疲劳载荷分别降低2.11%、4.89%,传动链高速轴等效疲劳载荷分别降低1.99%、4.78%,发电量分别降低200、700 k W·h。卡尔曼滤波对传动链扭角估计较准确,且以卡尔曼滤波估计得到的低速轴扭振速度设计的附加电磁转矩对传动链扭振具有非常好的抑制效果。

非共沸工质CO_(2)/R1234yf商超增压制冷系统性能分析

为满足商超制冷领域系统能效提升和制冷剂替代的需求,提出了非共沸工质CO_(2)/R1234yf商超增压制冷系统,通过建立热力学模型,与纯CO_(2)商超增压制冷系统进行对比。结果表明:CO_(2)/R1234yf商超增压制冷系统可在最优的CO_(2)质量分数(0.94)及最优排气压力(8.81 MPa)下获得最大COP(1.40);CO_(2)/R1234yf商超增压制冷系统COP与纯CO_(2)系统相比具有显著提升,环境温度为35℃时,提升7.25%;CO_(2)/R1234yf商超增压制冷系统APF提升率为2.68%~4.72%,系统APF随典型城市所处纬度的增加而增大。CO_(2)/R1234yf商超增压系统(火用)效率随CO_(2)质量分数的增加呈先增后减趋势,CO_(2)质量分数为0.95时获得最高(火用)效率,为0.18,相比纯CO_(2)系统提升4.62%。

基于BIM技术的地下污水厂结构优化设计研究

研究基于BIM技术的地下污水厂结构优化设计,降低地下污水厂能耗。将萧山钱江污水处理厂扩建工程作为研究对象,采集地下污水厂的实际运行数据并计算其年用电量与采暖能耗,以此为基础计算年用电量与采暖能耗的指标值,最终构建地下污水厂多指标耗能函数;基于BIM技术协同设计地下污水厂节能结构,通过地下污水厂的能耗总量与规定性指标设计出地下污水厂节能结构优化方案。实验表明:该方法能够降低地下污水厂的能耗总量,提高节能持续性。