Performance Evaluation of Compressed Air Energy Storage Using TRNSYS

The appreciable economic growth in some of the developing countries like India in the recent years, towards providing energy security causes large environmental impact. Renewable Energy (RE) is being seen as one of the important means to meet the growing power needs of the economy while enhancing energy security and providing opportunities for mitigating greenhouse gas emissions. However, RE sources are highly intermittent in nature. The variability of these sources has led to concerns regarding the reliability of an electric grid that derives a large fraction of its energy from these sources as well as the cost of reliably integrating large amounts of variable generation into the electric grid. Hence at this juncture, it is necessary to explore the benefits of suitable Energy storage technologies. Compressed air energy storage (CAES) is a commercial, utility-scale technology that provides long-duration energy storage with fast ramp rates and good part-load operation. It is a promising storage technology for balancing the large-scale penetration of renewable energies, such as wind and solar power, into electric grids. Considering the potential of CAES storage, the present work, a thermodynamic model is developed with suitable assumptions and the simulation analysis is performed using transient system simulation (TRNSYS) v17 software. The system performance is compared by considering the recovery during the heat of compression using a thermal storage system and without considering the heat recovery. The overall turnaround efficiency of the system without considering the thermal energy storage (TES) system is 57% and with TES system the efficiency is increased to 70%.     

Thermal and Mechanical Characteristics of a Multifunctional Thermal Energy Storage Structure

Thermal energy storage (TES) sandwich-structures that combine the heat storage function with structural functionality are described. The structure consists of a thermal interface (TI) connected to a hollow plate lamination. Each laminate is a hollow aluminum plate having a series of mm-scale channels or compartments that are filled with phase change material (PCM). Heat storage is via the latent heat of the PCM. A generalized thermal response model that is applicable to a wide range of channel geometrical configurations is described. The model couples the thermal response of the TI to the hollow aluminum plate/PCM-volume. The temporal response of the system is easily obtained via numerical solution of two ordinary differential equations, which can be solved to give closed-form solutions subject to a simple assumption. Thermal analysis delineates geometrical configurations that have good thermal response characteristics. The mechanical properties of the laminated structure are determined experimentally. Four-point bending experiments are conducted using specimens made with three layers of hollow plates laminated using a structural adhesive. An energy method is developed to model both the deformation and strength of the laminated structure. The energy method is developed based on the assumption that plane cross sections of the structure remain plane under bending, a condition that is valid for both linear and nonlinear materials. The energy method can provide deformation of the aluminum laminates comparable with the experiments. Experiments and modeling indicate that these laminated structures have an excellent performance-to-weight ratio.      

Microstructural Control of Charge Transport in Organic Blend Thin‐Film Transistors

The charge‐transport processes in organic p‐channel transistors based on the small‐molecule 2,8‐difluoro‐5,11‐bis(triethylsilylethynyl)anthradithiophene (diF‐TES ADT), the polymer poly(triarylamine)(PTAA) and blends thereof are investigated. In the case of blend films, lateral conductive atomic force microscopy in combination with energy filtered transmission electron microscopy are used to study the evolution of charge transport as a function of blends composition, allowing direct correlation of the film's elemental composition and morphology with hole transport. Low‐temperature transport measurements reveal that optimized blend devices exhibit lower temperature dependence of hole mobility than pristine PTAA devices while also providing a narrower bandgap trap distribution than pristine diF‐TES ADT devices. These combined effects increase the mean hole mobility in optimized blends to 2.4 cm²/Vs – double the value measured for best diF‐TES ADT‐only devices. The bandgap trap distribution in transistors based on different diF‐TES ADT:PTAA blend ratios are compared and the act of blending these semiconductors is seen to reduce the trap distribution width yet increase the average trap energy compared to pristine diF‐TES ADT‐based devices. Our measurements suggest that an average trap energy of <75 meV and a trap distribution of <100 meV is needed to achieve optimum hole mobility in transistors based on diF‐TES ADT:PTAA blends.     

Thermal Modeling of a Hybrid Thermoelectric Solar Collector with a Compound Parabolic Concentrator

In this study radiant light from the sun is used by a hybrid thermoelectric (TE) solar collector and a compound parabolic concentrator (CPC) to generate electricity and thermal energy. The hybrid TE solar collector system described in this report is composed of transparent glass, an air gap, an absorber plate, TE modules, a heat sink to cool the water, and a storage tank. Incident solar radiation falls on the CPC, which directs and reflects the radiation to heat up the absorber plate, creating a temperature difference across the TE modules. The water, which absorbs heat from the hot TE modules, flows through the heat sink to release its heat. The results show that the electrical power output and the conversion efficiency depend on the temperature difference between the hot and cold sides of the TE modules. A maximum power output of 1.03 W and a conversion efficiency of 0.6% were obtained when the temperature difference was 12°C. The thermal efficiency increased as the water flow rate increased. The maximum thermal efficiency achieved was 43.3%, corresponding to a water flow rate of 0.24 kg/s. These experimental results verify that using a TE solar collector with a CPC to produce both electrical power and thermal energy seems to be feasible. The thermal model and calculation method can be applied for performance prediction.     

Energy storage and heat deposition in flashlamp-pumped sensitizederbium glass lasers

Measurements of population inversion energy storage and heat deposition in flashlamp-pumped Nd:Yb:Er:glass and Cr:Nd:Yb:Er:glass lasers are reported. A thermal camera is used to measure temperature changes following isolated flashlamp pulses. A rate equation model is developed in order to determine energy storage from the output versus input energy characteristics of erbium lasers operating in a free-oscillation mode. Contributions of different sensitizers are distinguished by spectrally filtering flashlamp-pump radiation. Ratios of the deposited heat per unit stored energy in both glasses are compared for several spectral regions     

大功率LED有源温控系统的开发

由于大功率LED供电时其大部分能量转化为热能,如果热量不能有效散出,将严重影响其光照亮度及其使用寿命。为了大功率LED散热的实际需要,提出并实现了一种LED有源温控系统的开发,采用热电制冷效应,使用LED驱动器本身作为制冷器的驱动电源,同时建立基于半导体传感器的温控监测电路,通过内部数字PI调节器形成一个完整的闭环控制系统,最后获得LED有源温控系统的具体配置方式,并分析测试的数据结果,展示了有源温控系统的准确性和可靠性。     

Integrating Phase-Change Materials into Automotive Thermoelectric Generators

Because the heat emitted by conventional combustion-engine vehicles during operation has highly transient properties, automotive thermoelectric generators (TEG) are intended for a particular operating state (design point). This, however, leads to two problems. First, whenever the combustion engine runs at low load, the maximum operating temperature cannot be properly utilised; second, a combustion engine at high load requires partial diversion of exhaust gas away from the TEG to protect the thermoelectric modules. An attractive means of stabilising dynamic exhaust behaviour (thereby keeping the TEG operating status at the design point for as long as possible) is use of latent heat storage, also known as phase-change materials (PCM). By positioning PCM between module and exhaust heat conduit, and choosing a material with a phase-change temperature matching the module’s optimum operating temperature, it can be used as heat storage. This paper presents results obtained during examination of the effect of integration of latent heat storage on the potential of automotive TEG to convert exhaust heat. The research resulted in the development of a concept based on the initial integration idea, followed by proof of concept by use of a specially created prototype. In addition, the potential amount of energy obtained by use of a PCM-equipped TEG was calculated. The simulations indicated a significant increase in electrical energy was obtained in the selected test cycle.     

Transient thermal management of temperature fluctuations duringtime varying workloads on portable electronics

This paper describes the investigation of solid to liquid phase change materials (PCM's) for passive energy storage during the condition of time varying workloads on portable electronics. The model investigated includes a thermal control unit (TCU) embedded in an epoxy polymer. A TCU is an enclosure that contains phase change material (PCM) and a thermal conductivity enhancer, is located near the power source, and acts as an energy storage and heat-spreading module. Physical experiments were carried out to investigate the performance improvements of introducing a TCU into an embedded system and were used to validate the accuracy of the numerical model. Numerical simulations were performed to study the effect duty cycles and substrate thermal conductivities have on the thermal performance of the electronic wearable computer system with passive energy storage. Additionally, the TCU was numerically modeled to determine the influence of boundary conditions on TCU performance. To quantify the improvements of the system, metrics were developed from analyzing the thermal evolution of the TCU parameters, such as temperature fields, temperature bands, PCM characteristics, and power loads. Results indicate that using a TCU for passive energy storage significantly increases the portable electronics system's operational performance. Duty cycles with the same average power over the duration of the cycle do not influence the length of the PCM phase change time, but do impact the mean value of the temperature fluctuation bands     

电力系统中储能技术的应用

伴随着社会中的能源应用日益紧张,实现能源节约与储能技术应用,是新能源发展的关键.在电力系统中,更加需要储能技术,在人们的用电需求量逐渐增加的基础上,将储能技术与电力系统发展相互结合,能够有效的避免电力系统中能源浪费,并且推动新能源社会的发展.基于此,在本文中对电力系统储能技术应用进行研究.     

冰蓄冷低温送风系统节能分析及风管得热的讨论

分析冰蓄冷低温送风系统在风机和水泵等方面的节能性,结合焓湿图分析,对风管得热和温升进行了计算和讨论。     

A General Model for the Electric Power and Energy Efficiency of a Solar Thermoelectric Generator

A general model for the electric power and energy efficiency of a solar thermoelectric generator is discussed, considering the influences of the input energy, the thermal conductivity, the absorptivity and emissivity of the heat collector, and the cooling water. The influences of these factors on the performance of the thermoelectric device are discussed, considering the thermoelectric generator as a whole, including the heat collector, the thermoelectric device, and the cooling. Results show that high input energy, and high absorptivity and low emissivity of the heat collector, are helpful for obtaining a high-performance thermoelectric generator. A high thermal transfer coefficient of the cooling water can increase the temperature difference across the thermoelectric device but results in greater accessory power requirements if increased further.     

同轴送粉激光成形中粉末与激光的相互作用

详细介绍了同轴送粉激光成形过程中，金属粉末与激光束相互作用时间的计算方法。在ANSYS软件平台上，建立了金属粉末穿越激光束过程中粉末温度场的计算模型。系统计算了不同颗粒大小316L不锈钢粉末与不同功率激光束相互作用后的温度。在此基础上，计算了金属粉末与激光束的能量交换及金属粉末落入激光熔池后与激光熔池的能量交换。计算结果表明，在激光束直径为3mm条件下，316L不锈钢粉末穿过功率大于1000W的激光束后，所有尺寸金属粉末均被熔化，即金属粉末以液态进入激光熔池。通过金属粉末与激光束及激光熔池的能量交换计算，可知在激光成形中，约有5％的激光能量用于加热和熔化粉末，而大约95％的激光能量用于激光熔池的形成及由于热传导造成的热量损失。     

Optically Triggered Synchronous Heat Release of Phase-Change Enthalpy and Photo-Thermal Energy in Phase-Change Materials at Low Temperatures

Phase-change materials (PCMs) are used in several energy recycling utilization systems due to their latent-heat-storage and -release ability. However, the inability of PCMs to release heat at temperatures below their freezing point limits their application in distributed energy utilization systems. This paper reports optically-triggered low-temperature heat release in PCMs based on a solid–liquid phase change (PC) controlled by the trans–cis (E–Z) photo-isomerization of azobenzene. To achieve this, a photo-responsive alkyl-grafted Azo is incorporated into tetradecane (Ted) to create a photo-sensitive energy barrier for the PC. The Azo/Ted composite exhibits controllable supercooling (4.04–8.80 °C) for heat storage and achieves synchronous heat release of PC enthalpy and photo-thermal energy. In addition, the Azo reduces the crystallization of Ted by intercalating into its molecular alignment. Furthermore, under light illumination, the Azo/Ted composite releases considerable heat (207.5 J g⁻¹) at relatively low temperatures (−1.96 to −6.71 °C). The temperature of the annular device fabricated for energy utilization increases by 4 °C in a low-temperature environment (−5 °C). This study will pave the way for the design of advanced distributed energy systems that operate by controlling the energy storage/release of PCMs over a wide range of temperatures.     

主被动结合的储能电站分布式能源孤岛检测方法

为了提高储能电站分布式能源输出控制能力,需要进行储能电站分布式能源孤岛检测,提出基于主被动结合的储能电站分布式能源孤岛检测方法。首先分析储能电站的实时负荷优化分配模型,采用配电增益调度的方法,进行储能电站的实时负荷预测,利用储能电站的能量负载实时调度的方法进行输出转换控制。然后根据储能电站群的总负荷进行储能电站分布式能源信息评估,采用主被动结合的方法进行储能电站分布式均衡控制,最后通过电站三层负荷开销进行输出负载调节,实现储能电站分布式调节和总发电负荷指令控制,实现储能电站分布式能源孤岛检测。     

Room‐Temperature Self‐Organizing Characteristics of Soluble Acene Field‐Effect Transistors

We report on the room‐temperature self‐organizing characteristics of thin films of the organic small‐molecule semiconductor triethylsilylethynyl‐anthradithiophene (TES‐ADT) and its effect on the electrical properties of TES‐ADT‐based field‐effect transistors (FETs). The morphology of TES‐ADT films changed dramatically with time, and the field‐effect mobility of FETs based on these films increased about 100‐fold after seven days as a result of the change in molecular orientation from a tilted structure in the as‐prepared film to a well‐oriented structure in the final film. We found that the molecular movement is large enough to induce a conformational change to an energetically stable state in spin‐coated TES‐ADT films, because TES‐ADT has a low glass‐transition temperature (around room temperature). Our findings demonstrate that organic small‐molecule semiconductors that exhibit a low crystallinity immediately after spin‐coating can be changed into highly crystalline structures by spontaneous self‐organization of the molecules at room temperature, which results in improved electrical properties of FETs based on these semiconductors.     

储能技术在电力系统中的应用

经济的快速发展对能源的依赖性越来越强。电能是经济稳定增长强有力的保障,同时电力系统的发展也给环境带来很大破坏。因此,在促进电力系统高效安全运行时,需考虑减少对环境的破坏。储能技术是电网运行中的重要部分,它通过对电力需求的调整以加强再生能源的可利用率,来保障电力系统的正常运行。文中从我国电力储能现状、电力系统的现实需求进行分析,探讨了储能技术在电力系统中的应用。     

高能激光能量直接测量技术及其发展趋势

高能激光功率高、能量大,造成激光能量计容易损坏和测量不确定度增加。围绕上述问题对国内外现有的几种高能激光能量直接测量方法进行了比较和归纳,对各种技术的优点和缺点作了深入的分析,在此基础上阐述了高能激光能量直接测量技术的发展趋势。研究表明,提高热交换效率是提升高能激光能量计测量能力最高效的措施,尤其是在采用体吸收模式和强制热交换模式的情况下这种效果更加明显;消除吸收体上温度梯度对吸收体材料比热和温度传感器响应时间的影响是提高被动吸收型高能激光能量计测量准确度的关键,在水流冷却型高能激光能量计和水流直接吸收型高能激光能量计中消除水流相变的影响和控制水流温度场不均匀造成的影响则是保证温度准确测量的关键。目前各种高热交换效率和新体制的测量方法得到快速发展和应用,系统的测量能力和测量准确度大幅提高,为了适应未来长时间测量需求,能量累积型高能激光能量计逐渐被功率平衡型高能激光能量计所替代。     

Die Karbonatschmelzen-Brennstoffzelle — Grundlagen für den Kraftwerkseinsatz

Conventional energy transforming techniques aiming at power production are based on the Carnot process, in which process heat is supplied by burning fossil combustibles. In the fuel cell, power is generated directly by the fuel, i.e. chemically bound energy, by means of a reversible electrochemical change. As for the stationary use in the energy industry, the Molten Carbonate Fuel Cell (MCFC) pertaining to the high temperature fuel cells is particularly adequate, as the operating temperature in the range of 650 °C allows for an optimal waste heat utilization. In this paper, the bases of MCFCs for the use in power plants is illustrated by the example of the 1 MW pilot project of Kawagoe (Japan) being under construction.     

智能交通摄像机工作热负荷实验评价

利用红外热像技术,对某新型智能交通摄像机工作热负荷状况进行实验研究,并针对相机核心功耗元件DSP（数字信号处理器）和FPGA（现场可编程门阵列）开展了模拟芯片实验。原机实验结果表明,相机工作热负荷对芯片性能的影响不容忽视,即便处于只进行图像采集而不做图像处理的较低功耗模式下,不加散热器时DSP芯片表面温度已接近设计上限,因而有必要进行相机散热结构优化设计。模拟芯片实验证实,芯片功率对其表面温度有显著影响,功率越高,芯片温度呈近似线性增长,同时散热器瞬时储热能力有所减弱,因此合理控制芯片功率可有效降低相机工作热负荷。对比分析相机辅助散热器热阻可知,该散热器效率较低,存在进一步优化潜力。     

基于无线传感网络的电力电缆接头在线监测系统

针对现有的电力电缆接头温度在线监测系统存在的问题和缺陷,研制出一套新型的监测系统。该监测装置以ATmega16单片机和UTC1212无线透传模块为核心,对电缆接头温度数据采集和监测,利用GPRS网络来实现远程数据的传输。终端采用感应取能供电,利用超级电容的大容量储能和快速充放电特性,经储能超级电容和放电超级电容输出给监测系统供电。