功率比可变的非能动核电站SBO事故比例分析研究

针对非能动核电站的全厂断电(SBO Station Blackout)事故开展了比例分析研究,建立了重要热工水力现象的数学模型和相似准则。结合SBO事故特征,提出了一种功率比可变的试验模拟方法,并利用Relap5程序进行了分析验证。结果表明:在非能动电站的SBO事故中,自然循环回路动量控制方程的非定常项为阻力项和驱动力项的高阶小量,可采用稳态动量方程进行比例分析;对于几何结构已固定的整体性试验台架,通过调节试验回路的形状阻力值,能够以多种功率比例关系进行SBO事故的试验设计和模拟,拓展了已有整体性试验台架的适用范围。     

核电蒸汽发生器热工水力静态特性计算分析研究

根据秦山核电站一期30万kW蒸汽发生器的结构和设计参数,对U形管立式蒸汽发生器进行了热工水力计算分析研究,计算了在不同功率水平下,无污垢和无堵管的新蒸汽发生器状态以及有污垢和堵管量达到10%的状态分别对应的蒸汽发生器的一回路和二回路总换热系数、二次侧的蒸汽出口压力和循环倍率等热工参数,得出它们与功率负荷的关系曲线并进行了静态特性分析研究,获得了一套关于蒸汽发生器热工水力计算方法与程序。     

压水堆比例试验中反应堆压力容器下降段宽度的确定

本文采用H2TS比例分析方法对比例试验中压力容器下降环腔的宽度进行了比例分析,得到了相似设计准则,分析表明为了能够准确的模拟下降段重要的物理现象需要考虑四个与宽度设计相关的相似准则,在设计不同比例的整体性试验台架时,需要综合考虑各现象的相似比例设计要求。     

压水堆失水事故降压过程低压试验模拟相似性分析

采用低压整体试验系统来模拟先进非能动压水堆核电站破口事故是一种经济可行的方法,其中试验降压阶段比例分析以及试验失真评价是低压试验方法中的核心部分。本文以基于两相混合模型的系统降压控制方程为基础,通过对方程无量纲化得到了降压模拟的相似准则,同时分析了不同事故条件下系统需优先保证的相似准则,进一步对各个相似失真度进行了定量化计算。结果表明,降压模拟失真随系统间压力比例的减小而增加。本文可为缩比低压试验台架的设计和试验结果的相似性评价提供参考。     

柴油机台架模拟整车道路循环的方法研究

基于整车的中国货车行驶工况(CHTC-LT)循环路谱,提出依托柴油机测试台架为平台模拟整车路谱的试验方法,引入线性回归分析作为试验有效性的判断依据。试验结果表明:转速、扭矩和功率满足线性回归要求,台架实测油耗与整车转毂油耗吻合,表明基于柴油机台架模拟整车路谱方法具有可行性。     

发动机性能测试及扭矩控制原型建立方法研究

分析了混合动力系统中发动机的工况特点,阐述了发动机性能自动测试方法,给出了如何运用MATLAB软件对测试数据进行插值、瞬态数据降噪及获得建立查表模型所需数据的方法。运用MATLAB/SIMULINK建立了发动机稳态扭矩控制原型和瞬态扭矩估计模型,并基于dSPACE系统将所建立的控制原型用于台架试验。试验结果表明:稳态扭矩控制原型的控制误差在5%以内,瞬态扭矩估计模型的估计误差在中高负荷时小于5%,两个模型均能满足并联混合动力系统工作模式切换协调控制的需要。     

整体比例试验中PRHR比例分析与相似准则

在非能动核电站当中,PRHR(非能动余热排出,Passive Residual Heat Removal)是非能动安全系统的重要组成,是事故后、尤其是全厂断电事故后,用于载出堆芯衰变热的重要途径。在高度比例降低的整体试验中,要保证PRHR中的现象与原型的相似性,需要通过理论分析和推导,从理论上证明模拟的准确性,并得到相关的设计准则,才能保证整体试验结果的准确性。通过对事故进程中PRHR主要物理过程和现象进行识别和分析,并进行PRHR的比例分析,得到PRHR在整体试验台架进行事故模拟过程时所需满足的关键比例准则。对不同缩比尺度的比例分析和失真评价结果表明,缩比台架中PRHR的相似准则不能同时得到满足,需要根据试验目的进行选择和取舍;台架整体的高度比(长度比)越接近1,则失真越小。     

低温下电池系统台架试验液冷控制方法的优化研究

随着电动汽车快速发展,对动力电池性能的要求日益严苛,电池热管理技术的升级优化变得十分迫切。由于国内缺乏电池系统试验水冷控制策略规范,台架试验与整车试验中的电池系统性能表现差异较大,导致试验结果严重脱节,系统级试验失去了原有的测试验证意义。本文对液冷台架试验方法的实际应用开展研究,通过功率、冷却液比热容、进出水口温差、流量等因素的关联计算,优化了电池系统台架液冷控制方法,使台架试验能够更好地模拟实际整车水冷情况。通过对电池系统进行 -20℃低温快充、-10℃低温快充和 -20℃低温慢充三项试验,验证了该电池系统台架液冷控制方法在低温下的改善效果。相较于传统台架液冷试验方法,采用该液冷控制方法能够使电池系统的温度及电性能更符合实际整车变化,保证了电池系统在系统级试验阶段与整车级试验结果保持一致,实现了电池系统在台架液冷试验的真实性能考核。     

基于嵌入式PC的活塞热冲击试验台架自动控制系统

在超低温启动等突变工况下,活塞的热负荷剧烈变化,为研究该过程中活塞温度及热应力的变化情况,研制了以嵌入式PC PC为控制核心的活塞热冲击试验台架,文中并详细介绍了该试验台架控制系统的硬件及软件设计并对PLC和嵌入式PC的性能进行了对比,对基于嵌入式PC试验台架及基于PLC试验台架的测试结果进行对比,前者可以实现活塞温度等参数的瞬态采集,为研究发动机活塞突变工况下的热负荷提供可靠的试验数据。     

用RELAP5程序分析压力容器喷放过程

压力容器实验；ＲＥＬＡＰ５；热工水力数值模拟摘 要：利用 Ｉｄａｈｏ Ｎａｔｉｏｎａｌ Ｅｎｇｉｎｅｅｒｉｎｇ Ｌａｂｏｒａｔｏｒｙ（ＩＮＥＬ）开发的 ＲＥＬＡＰＳ程序模拟压力容器事故卸压实验的热工水力过程。ＲＥＬＡＰ５程序的计算结果与实验数据相比，空泡份额变化与实验一致，压力和温度偏低，剩余水的质量偏大。程序预测的卸压过程比实验测量偏快．经过比较，认为ＲＥＬＡＰＳ程序可以对一般受压流体失压瞬态问题进行预测估算。     

Releases from hydrogen fuel-cell vehicles in tunnels

An important issue concerning the safe use of hydrogen-powered fuel-cell vehicles is the possibility of accidents inside tunnels resulting in the release of hydrogen. To investigate the potential consequences, a combined experimental and modeling study has been performed to characterize releases from a hydrogen fuel-cell vehicle inside a tunnel. In the scenario studied, all three of the fuel-cell vehicle’s onboard hydrogen tanks were simultaneously released through three thermal pressure relief devices (TPRDs) toward the road surface. Computation fluid dynamics (CFD) simulations were used to model the release of hydrogen from the fuel-cell vehicle and to study the behavior of the ignitable hydrogen cloud inside the tunnel. Deflagration overpressure simulations of the hydrogen cloud within the tunnel were also performed for different ignition delay times and ignition locations. To provide model validation data for these simulations, experiments were performed in a scaled tunnel test facility at the SRI Corral Hollow Experiment Site (CHES). The scaled tunnel tests were designed to resemble the full-scale tunnel simulations using Froude scaling. The scale factor, based on the square route of the ratio of the SRI tunnel area to the full-scale tunnel area was 1/2.53. The same computational models used in the full-scale tunnel simulations were applied to these scaled tunnel tests to validate the modeling approach.     

Hydrogen fuel-cell forklift vehicle releases in enclosed spaces

Sandia National Laboratories has worked with stakeholders and original equipment manufacturers (OEMs) to develop scientific data that can be used to create risk-informed hydrogen codes and standards for the safe operation of indoor hydrogen fuel-cell forklifts. An important issue is the possibility of an accident inside a warehouse or other enclosed space, where a release of hydrogen from the high-pressure gaseous storage tank could occur. For such scenarios, computational fluid dynamics (CFD) simulations have been used to model the release and dispersion of gaseous hydrogen from the vehicle and to study the behavior of the ignitable hydrogen cloud inside the warehouse or enclosure. The overpressure arising as a result of ignition and subsequent deflagration of the hydrogen cloud within the warehouse has been studied for different ignition delay times and ignition locations. Both ventilated and unventilated warehouses have been considered in the analysis. Experiments have been performed in a scaled warehouse test facility and compared with simulations to validate the results of the computational analysis.     

The NASA-Langley building solar project and the supporting Lewis solar technology program

The National Aeronautics and Space Administration will use solar energy to heat and cool a new office building that is now under construction at its Langley Research Center in Hampton, Virginia. Planned for completion in December 1975, the 53,000 ft², single story building will utilize 15,000 ft² of various types of solar collectors in a test bed to provide nearly all of the heating demand and over half of the air conditioning demand. This is a cooperative project involving joint participation between Langley and NASA's Lewis Research Center in Cleveland, Ohio.Drawing on its space-program-developed skills and resources in heat transfer, materials and systems studies, NASA-Lewis will provide technology support for the Langley building project. A solar energy technology program underway at Lewis includes solar collector testing in an indoor solar simulator facility and in an outdoor test facility, property measurements of solar panel coatings, and operation of a laboratory-scale solar model system test facility. Based on results obtained in this program, NASA-Lewis will select and procure the solar collectors for the Langley test bed. The selection will be made in late 1974 or early 1975.Early results from simulator tests indicate that non-selective coatings behave more nearly in accord with predicted performance than do selective coatings. Initial experiments on the decay rate of thermally stratified hot water in a storage tank have been run. Results suggest that where high temperature water is required to drive a chiller, excess solar energy collected by a building solar system should be stored overnight in the form of chilled water rather than hot water.     

Ten years of solar hydrogen demonstration project at Neunburg vorm Wald,Germany

Major system components of possible future energy supply based on hydrogen generated by utilizing (solar) energy unaccompanied by release of carbon dioxide are installed on an industrial scale at a demonstration facility located in Neunburg vorm Wald, Germany. Initial technical aspects of stepwise transition from present-day energy supply aligned primarily to fossil fuels are considered. Most of the plant subsystems constitute prototypes of innovative technologies. Among others, the facility comprises: photovoltaic solar generators, water electrolyzers, catalytic and advanced conventional heating boilers, a catalytically heated absorption-type refrigeration unit, fuel cell plants for stationary and mobile application, and an automated LH₂ filling station for test vehicles.Focal points of the investigations being carried out under the project are performance of the plant subsystems and their interaction under practical operating conditions. Analysis of the work is yielding a reliable database for updated assessment of the prospects and challenges of (solar) hydrogen technology.The present review (current to October 1997) concerns primarily the technology and operation of the facility with regard to the objectives and perspectives of the project. Results of the test programs are not reported in explicit detail; rather, they are communicated by integrating them into the more practical records of overall plant operation.     

Grid-connected intermittent renewables are the last to be stored

When hydroelectric power systems became widespread, associated developments for energy storage, using pumped water, soon followed. Many other methods of storage have since been considered. Today's interest in other renewables, notably wind energy has led to assertions that, because it is intermittent, wind can make no contribution to the firm power on a power system (i.e., it has no capacity credit) but that storage can make it viable. Here we show that such assertions about intermittent renewables like wind are false – they can and do make contributions to firm power and storage has no special contribution to make for them. However, their main contribution is to fuel saving and storage is counter-productive for that because the losses in the storage and regeneration round-trip would represent a waste of fuel that had already been saved. More importantly, the energy being stored comes from those generators that were the last ones brought on line to supply the extra energy that is being stored, which would be the first to be shut down if the storage stopped, e.g., because the store was full or had broken down. These will be (marginally) the most expensive generation on line, the (marginally) cheapest generation always having being used first. Renewables have no fuel costs, so their (marginal) cost is zero, which must always make them (marginally) the cheapest power on the system, whenever they are available. So they will always be the last to be shut down or stored. When storage is installed, grid-connected intermittent renewables like wind energy will never be stored unless nothing else is available.     

A full-scale prediction method for wind turbine rotor noise by using wind tunnel test data

The development of a low-noise wind turbine rotor and propeller is often cost-effective and is in fact a race against time to those who wish to build and test a small-scale rotor instead of an expensive full-scale rotor. The issue of this approach has to do with the interpretation of wind tunnel model test data in terms of both the frequency band and sound pressure level information for the noise scaling effect.This paper discusses a prediction method for the estimation of the noise generated from a full-scale wind turbine rotor using wind tunnel test data measured with both a small-scale rotor and a 2D section of the blade. The 2D airfoil self-noise and the scaled rotor noise were investigated with a series of wind tunnel experiments. Wind tunnel data post-processing considered four aspects: removal of the test condition effect, scaling to full scale, consideration of the wind turbine rotor operating conditions, and the most important terms of full-scale rotor noise as adjustments to address the differences between the wind tunnel test conditions and the full-scale operating conditions.A full-scale rotor noise prediction results comparison was performed by initially dividing the test conditions into the condition of a 2D section noise test and the condition of a small-scale rotor noise test. Based on an airfoil section, the rotor was selected from a blade section at r/R = 0.75. The small-scale rotor was scaled down by a factor of 5.71 for the wind tunnel test.Finally, the full-scale rotor noise data was compared with the wind tunnel test data using a scaling estimation method.     

Guidelines and recommendations for indoor use of fuel cells and hydrogen systems

Hydrogen energy applications often require that systems are used indoors (e.g., industrial trucks for materials handling in a warehouse facility, fuel cells located in a room, or hydrogen stored and distributed from a gas cabinet). It may also be necessary or desirable to locate some hydrogen system components/equipment inside indoor or outdoor enclosures for security or safety reasons, to isolate them from the end-user and the public, or from weather conditions.Using of hydrogen in confined environments requires detailed assessments of hazards and associated risks, including potential risk prevention and mitigation features. The release of hydrogen can potentially lead to the accumulation of hydrogen and the formation of a flammable hydrogen-air mixture, or can result in jet-fires. Within Hyindoor European Project, carried out for the EU Fuel Cells and Hydrogen Joint Undertaking safety design guidelines and engineering tools have been developed to prevent and mitigate hazardous consequences of hydrogen release in confined environments. Three main areas are considered: Hydrogen release conditions and accumulation, vented deflagrations, jet fires and including under-ventilated flame regimes (e.g., extinguishment or oscillating flames and steady burns). Potential RCS recommendations are also identified.     

Quantitative ranking criteria for PEMFC contaminants

The fuel cell performance effects of many contaminants originating from multiple sources such as air, fuel, and system materials release need to be determined to reduce risks associated with market introduction. A significant amount of time and resources are required to test the performance effects of all possible contaminants because contaminant impacts develop slowly at concentrations reflecting practical operation. Thus, a two tiered down selection process was proposed to identify specific contaminants for more detailed studies. The methodology used to generate the second tier down selection is presented and discussed in relation to a specific contaminant, sulfur dioxide. Two quantitative criteria were derived based on parameters defined using the cell performance response to a temporary contaminant injection. These quantitative criteria were applied to sulfur dioxide data to investigate the effects of different operating conditions and determine the most relevant selection criterion. Results showed that the method which considered the ratio of the energy lost during contaminant exposure to the energy recovered subsequent to the contaminant exposure is preferable in this case because values are less dependent on operating conditions. Furthermore, the energy lost to energy recovered ratio is also preferable because high values not only identify the contaminants with the most significant performance loss and least performance recovery but also identifies contaminants with a performance recovery that exceeds the performance loss.     

Experimental investigation of hydrogen release and ignition from fuel cell powered forklifts in enclosed spaces

Due to rapid growth in the use of hydrogen powered fuel cell forklifts within warehouse enclosures, Sandia National Laboratories has worked to develop scientific methods that support the creation of new hydrogen safety codes and standards for indoor refueling operations. Based on industry stakeholder input, conducted experiments were devised to assess the utility of modeling approaches used to analyze potential consequences from ignited hydrogen leaks in facilities certified according to existing code language. Release dispersion and combustion characteristics were measured within a scaled test facility located at SRI International's Corral Hollow Test Site. Moreover, the impact of mitigation measures such as active/passive ventilation and pressure relief panels was investigated. Since it is impractical to experimentally evaluate all possible facility configurations and accident scenarios, careful characterization of the experimental boundary conditions has been performed so that collected datasets can be used to validate computational modeling approaches.