THERMOCAPILLARY-DRIVEN FLOW PAST THE MARANGONI INSTABILITY

A top pee liquid layer is heated from the bottom in a two-dimensional rectangular container with insulated side walls. The resulting thermacapiUary motion is predicted by the projection method involving a Godunov-type discretization for convective terms. The velocity and temperature fields beyond those predictable via infinitesimal theories are discussed in terms of the Marangoni number, Prandtl number, Biot number, and aspect ratio.     

光伏阵列倾角对性能影响实验研究

对8块不同朝向和倾角的太阳电池组件输出情况进行了为期一年多的测试,并对实验结果进行了详细的分析和研究.得出:水平布置以及小倾角布置时,灰尘、雨水等因素对光伏阵列产能有较大影响;全年以朝向正南220倾角太阳电池组件产出的电能最多.     

ISOTHERMAL FLOW DISTRIBUTION IN HEADER SYSTEMS

Flow distribution in header systems is studied both numerically and experimentally in the present work. A discrete numerical model describing the flow behavior is formulated in terms of mass and momentum balance equations at every segment of the header system. The numerical results show that the header systems can be categorized as pressure regain type and pressure decrease type according to the static pressure distribution along the dividing manifold. A header system may transfer from pressure regain type to pressure decrease type while the resistance of the dividing manifold increases. The flow distribution of pressure regain header system is much more uniform than that of pressure decrease header system. It is found that the numerical results obtained by the present model are in good agreement with the experimental results for both types of header systems.

A parametric study on the performances of header systems is also presented in this paper.     

TRENDS IN THE DEVELOPMENT OF PHOTOVOLTAIC GENERATING SYSTEMS IN NEDO

The optimal exergy-based ecological performance of a generalized irreversible Carnot refrigerator with losses of heat resistance, heat leakage and internal irreversibility is derived by taking an ecological optimization criterion as the objective. The transfer between the working fluid and heat reservoirs obeys a generalized heat transfer law Q∝ Δ (T ⁿ ) ^m . Some special examples are discussed. Results include the optimal ecological performance of the irreversible Carnot refrigerator with various heat transfer laws, which were obtained in many studies, and can provide some theoretical guidelines for the design of practical refrigerators.     

风电齿轮箱行星轮系的齿面摩擦与齿根裂纹耦合效应计算方法

针对风电增速箱故障率偏高的问题,在对风电机组传动系统的振动响应机理进行分析的基础上,提出一种同时考虑齿根裂纹与齿面摩擦2种因素耦合情况下计算风电增速箱行星轮系动态响应的方法。首先分析考虑不同滑动摩擦因素时,含齿根裂纹缺陷的齿轮其啮合刚度的变化情况;随后运用集中参数法建立一种同时考虑平移和扭转2种力学效应相互影响作用的行星轮系动态响应计算模型。使用该模型在考虑齿根裂纹、齿面滑动摩擦2种因素耦合情况下,对行星轮系时变啮合刚度影响作用进行仿真计算。结果表明,齿面间的滑动摩擦力将导致行星齿轮扭转振动响应在低频区域受到抑制、中频区域得到增强,而齿根裂纹会导致系统出现调制效应且该效应会使行星齿轮的扭转振动频谱响应在行星轮与太阳轮间的啮合频率附近出现调制边频带现象。     

太阳能-土壤蓄热融雪系统融雪机理的研究

利用FLUENT对太阳能融雪系统路面冰雪融化过程进行数值模拟,得出路面融雪的温度场及相界面移动规律.对系统参数的选择进行分析,得出融雪所需时间与影响太阳能融雪系统工作特性的一些参数(外界环境条件、管径、埋管深度、管间距)的关系.所得结论对太阳能-土壤蓄热融雪系统路面部分的设计以及优化有重要的参考价值.     

CHANNEL-TO-CHANNEL PRESSURE DIFFERENCES IN SERPENTINE MINICHANNEL FLOW SYSTEMS

One of the interconnected factors that can lead to failures in the flow plates of PEM fuel cells is the pressure differences that exist between adjacent flow channels. These pressure differences lead to stresses in the channel supports—i.e., the ribs—which can be important in the presence of stresses arising due to other factors such as temperature gradients in the flow plates. In order to investigate the magnitudes of the pressure differences across the supports and the places where the maximum pressure differences occur, the flow and pressure variations in various forms of serpentine channels, these channels having a rectangular cross-sectional shape, have been numerically calculated. The presence of the diffusion layer has been ignored and the flow has been calculated using a commercial finite-element software package using the governing equations written in dimensionless form. Solutions have been obtained for various values of the Reynolds number for each of the flow geometries considered for two channel height-to-width ratios (one and three). Except for the flow in the vicinity of the bends in channels, the pressure has been found, as is to be expected, not to vary significantly across the channel cross section. The difference between the center point dimensionless pressure in a given channel with those at the same longitudinal position in the adjacent channels has been determined. The dependence of the highest dimensionless pressure difference between channels on the input parameters has been examined. 273pt     

小型空调系统中碳氢化合物替代HCFC22的研究

以小型空调系统中HCFC22替代为应用背景，对碳氢化合物（HCs)及其混合物系进行了系统的理论循环分析，表明HC1270、HC290、HC1270／HC290、HC1270／HC600a、HC290／HC600a等具有在空调系统中替代HCFC22的潜力。对容积制冷量与HCFC22相近的HCs，在HCFC22窗机中进行了灌注式替代实验研究，结果表明，HCs的性能指标全面优于HCFC22。对不同工质间的公平实验比较、HCs应用中的安全性等问题进行了讨论。     

A THEORETICAL STUDY OF THE RECYCLE EFFECT ON HEAT TRANSFER EFFICIENCY IN COOL-THERMAL DISCHARGE SYSTEMS FROM ICE MELTING WITH PRODUCING CHILLED AIR

The influence of the recycle effect on cool-thermal discharge systems in a parallel-plate channel with one side cooled by melting ice and the other side insulated is studied theoretically. The mathematical formulations are developed with moving boundary and the theoretical predictions are calculated using the integral boundary layer to estimate the required air mass flow and outlet chilled air temperature. Theoretical results show that the recycle operation can effectively enhance the heat transfer efficiency compared with that in the device without external refluxes. Numerical examples of inlet ambient air temperatures varied with time are illustrated to simulate practical systems from sunrise to sunset. The power consumption increment is also discussed.     

电力系统短期负荷预报

展示了从１小时至１周内电力系统短期负荷预报模型与方法的现状及最新发展，讨论了两类八种的主要特性，指出了负荷预报精度的途径，并给出了有关的结论。     

THE MARKET POTENTIAL OF PHOTOVOLTAIC SYSTEMS IN NIGERIA

This paper discusses the viability and readiness of the photovoltaics (PV) market in Nigeria. An opportunity for decentralized sources like PV has been opened up by the finding that it is currently impractical for the centralized grid to meet all of Nigeria's rural electricity demand. PV is identified as the most economical decentralized source to contribute to rural development. The current low level of PV utilisation in the country has been identified as being chiefly due to lack of awareness among potential buyers and energy planners of its large-scale applicability. With increasing awareness, some industrialist and government agencies (as well as some wealthy individuals) have now installed PV systems for home-lighting, water-pumping, and rural electrification, etc. This paper reviews this activity and also suggests some other new uses. Generally the PV installations have been found to be successful, and so PV markets have been springing up to meet the demand. The role the government could play in fully introducing and harnessing PV technology is also discussed in this paper.     

含电池储能系统的电热联合系统风电接纳能力评估

为促进风电消纳,减少“弃风”,将电池储能系统（BESS）接入电热联合系统。为考虑风功率的不确定性,基于风功率预测误差的概率特性建立风功率场景概率模型。然后,建立包含BESS的电热联合系统风电接纳能力评估模型。模型具有系统运行成本最低和“弃风”电量最小2个不同维度优化目标,且目标优化之间可能存在冲突。为求解该模型,基于改进主要目标法将其转换为多个单目标优化问题,并采用GAMS中DICOPT求解器给出风电接纳能力评估模型的帕累托解集。基于帕累托解集,从接纳电量和接纳成本两方面对BESS接入后的电热联合系统风电接纳能力进行深入分析。最后进行仿真分析,验证了该文所提模型及求解算法的有效性。     

OPTIMIZATION OF COLLECTOR AREA IN SOLAR WATER HEATING SYSTEMS

Domestic household thermosyphons are economically feasible and are used by over than 70% of houses in Palestine. Although domestic solar water heating for commercial applications has a good potential, only a few systems have been installed in Palestine. A systematic sizing approach for the solar system is presented in this paper and applied to a certain case study. The solar system sizing is based on the life-cycle cost LCC analysis. For the chosen case study of domestic water heating for a hotel, with hot water consumption of 2600 liters per day, the optimum collector area was found to be 37 m², the solar fraction of heating 0.78, the LCC of system is SI 3778, with annual savings of 1338$/year and a pay back period of 3 years. With this optimized system, the cost of water heating is 1.8 $/m³comparing with 2.6 $/m³ for the conventional system.     

A REVIEW OF LARGE-SCALE SOLAR HEATING SYSTEMS IN EUROPE

Large-scale solar applications benefit from the effect of scale. Compared to small solar domestic hot water (DHW) systems for single-family houses, the solar heat cost can be cut at least in third. The most interesting projects for replacing fossil fuels and the reduction of CO₂-emissions are solar systems with seasonal storage in combination with gas or biomass boilers. In the framework of the EU–APAS project “Large-scale Solar Heating Systems”, thirteen existing plants in six European countries have been evaluated. The yearly solar gains of the systems are between 300 and 550 kWh per m² collector area. The investment cost of solar plants with short-term storage varies from 300 up to 600 ECU per m². Systems with seasonal storage show investment costs twice as high. Results of studies concerning the market potential for solar heating plants, taking new collector concepts and industrial production into account, are presented. Site specific studies and predesign of large-scale solar heating plants in six European countries for housing developments show a 50% cost reduction compared to existing projects. The cost–benefit-ratio for the planned systems with long-term storage is between 0.7 and 1.5 ECU per kWh per year.     

广州地区薄膜光伏并网电站性能研究

对3个薄膜光伏并网电站(12dTe、CIGS、a-Si,以下简称电站)进行了描述,对2008年2月～2009年1月的数据进行了分析.根据设计,电站每3min采集一次数据.对一年中3个电站的年发电量、月发电量、太阳辐照、光伏阵列的功率、电站效率、电站的功率损失进行了对比分析.对2008年3月21日(阴天)和24日(晴天)逆变器的工作状况进行了分析.结果表明:在2008年中,CdTe、CIGS、a-Si 3个电站每千瓦的发电量依次为994.74、954.42、936.07kWh.CdTe电站在2008年中发电量最多.通过对3个电站每个月发电量的分析发现温度对CIGS电站的发电量影响较大,适合在气温较低的地区使用.最后指出通过优化太阳电池的质量可以优化温度系数,也可以通过新颖的设计改善电站和太阳能组件(简称组件)的散热从而提高电站的效率.     

多机系统中考虑多种运行方式的飞轮储能系统稳定器设计

针对基于某运行点设计的飞轮储能系统(FESS)稳定器不能保证鲁棒性问题,提出考虑多种运行方式的FESS最佳安装地点、控制回路和反馈信号选择以及FESS稳定器参数整定的改进方法。在推导了含FESS的多机系统线性化模型的基础上,应用阻尼转矩分析法,将多种运行方式下的最小阻尼转矩指标中的最大值作为FESS安装地点、控制回路和反馈信号的选择指标,以改变特征值实部最小的运行方式作为整定FESS稳定器参数的运行方式,并以FESS接入四机系统为例,分析结果表明应用该方法设计的FESS稳定器在多种运行方式下都能有效抑制低频振荡,验证了方法的有效性,且具有一定的鲁棒性。     

多元醇二元体系固－固相变贮热的研究

用ＤＳＣ法研究季戊四醇－新戊二醇（ＰＥ－ＮＰＧ），三羟甲基乙烷－新戊二醇（ＰＧ－ＮＰＧ），季戊四醇－２－氨基２－甲基１，３丙二醇（ＰＥ－ＡＭＰ），三羟甲基乙烷－２－氨基２－甲基１，３丙二醇（ＰＧ－ＡＭＰ）和三羟甲基氨基甲烷－新戊二醇（ＴＡＭ－ＮＰＧ）五个多元醇二元体系的固一固相变。这些二元固体溶液的转变温度和转变热与其组成有依赖关系。研究结果可以指导选择贮热材料的组成。     

低温地板采暖与散热器采暖效果的对比分析

通过地板，墙面和人体之间的辐射换热计算，分析了地板采暖比暖气片采暖节能的原因，对比了两种采暖方式温度场水平分布和垂直分布的差异，空间气流分布的差异以及两种采暖方式热源热储量的差别。通过实测数据的对比表明地板采暖在多方面优于暖气片采暖方式。     

地热利用智能化管理系统的设计

该文主要描述分站式地热利用信息智能化管理系统中的逻辑结构、网络接口和空间数据库的设计方法;在进行实时监控中,对数据及运行状态控制过程的方法.通过采用管理信息系统MIS、地理信息系统GIS、智能信息系统、计算机网络系统、无线通讯以及强大的数据库管理系统,保证了数据信息的真实性和完整性,促进了对所有地热站点的分权管理,提高了科学化管理的水平和效率.     

水文水资源决策支持系统研究的新进展

综述国际上近年来在水文水资源决策支持系统领域研究的新进展和动态，剖析决策支持系统的组成和关键技术，给出水库优化调度等应用实例，并展望其发展前景