基于圆柱形单元的储热装置放热实验研究

蓄热水箱作为太阳能供暖系统的重要核心设备,其性能直接影响着储能系统的整体运行效率。设计一种基于圆柱形相变单元的相变储热装置,并搭建相变蓄热水箱性能测试平台,通过单一控制变量法得到储热装置放热过程的温度变化曲线。研究表明：对于空间一定的储热装置,在等质量相变材料（PCM）时,相变单元的直径对装置放热速率的影响较大;相变单元之间的间距对装置放热速率的影响较小;当增大换热流体（HTF）的入口流量及降低HTF入口温度时,能大大减少储热装置的放热时间,提高储热装置的整体性能。     

肋片增强式梯级相变储热系统放热特性的三维数值

梯级相变储热技术已被证明是解决相变材料导热性能差的重要方法。已有的关于梯级相变储热系统的数值研究通常是基于一维或二维数学模型完成的,大部分的研究聚焦于系统的储热过程。本工作设计了一种肋片增强型三管式梯级相变储能系统,并建立了三维数值模型。然后研究了系统放热过程中各级PCM的性能变化规律,探究了传热流体进口温度和PCM初始温度对系统放热速率的影响规律。结果表明,在放热过程中,各级PCM相变不会同时发生,受到储热材料的相变温度和潜热的影响最大。传热流体进口流速的增大会提高相变材料的放热速率,但随着流速的进一步增加,放热速率的提高程度明显减弱。相变材料的初始温度对显热放热过程具有一定的影响,但对于潜热放热阶段影响较小。     

组合相变材料储热系统的储热速率研究

建立了组合式柱内封装相变材料熔化－固化循环相变储热系统的物理模型,用有限差分法进行了数值模拟求解。结果表明,与采用单一相变材料的传统储热系统相比,在给定相变材料组合方式和传热流体进口温度条件下,传热流体流量存在最佳值;选用三种石蜡作用相变材料和水作传热流体的模拟计算结果表明,相变速率可提高１５％￣２５％左右。     

圆柱形相变蓄热器蓄/放热性能实验研究

设计并搭建了以太阳能为热源的圆柱形蓄热器实验台,将封装了相变材料(PCM)的蓄热球体放置在蓄热器中,测量蓄热器进出口和蓄热器内第一～七层的热媒(HTF)温度,对所测温度和流最进行数据采集.分析HTF的进口温度和流量变化对蓄热器热性能的影响.结果表明,随着HTF的进口温度的提高,完成蓄热所需的时间不断减少,蓄热效率得到提高,流速的增加对蓄热的影响不大.初步掌握热媒的流动特性对相变蓄热装置蓄放热过程的影响,为蓄热器的工程应用设计、评价提供参考依据.     

圆柱形等距螺旋盘管式相变蓄热装置蓄热性能研究

文章设计了一种以石蜡为相变材料的圆柱形等距螺旋盘管式相变蓄热装置,并通过实验分析了该装置的传热特性,以及传热流体入口温度、入口流量对石蜡的融化特性、相变蓄热装置的蓄热量及相变蓄热系统总传热系数的影响。分析结果表明:融化后期,石蜡的融化速率会明显加快;当传热流体入口温度一定时,随着入口流量逐渐增大,蓄热装置的最终显热蓄热量略微升高;与传热流体入口流量相比,传热流体入口温度对石蜡融化速率影响较大;相变阶段,石蜡的传热性能较强,传热流体入口温度越高,石蜡的传热性能越不稳定。     

新型进水结构对太阳能分层水箱热特性影响的研究

蓄热技术是太阳能光热利用的重要组成部分,而以水作为蓄热介质的中低温蓄热技术是太阳能热利用系统中的关键技术之一。本研究设计了一种新型进口均流器,并搭建了一套储热水箱热力学特性测试实验台。在初始水温50℃、进水温度20℃的工况下,分析对比了不同流量下储热水箱的热力学特性。结果显示:均流器提高了分层蓄热水箱的分层效果以及水箱的效率。在同一进口流量下,水箱的热分层效率先增大后减小。而随着无量纲时间的增加,水箱的火用效率逐步降低,此外,水箱的火用效率还随着流量的增加,先增大后减小。当无量纲时间为0.6时,进口流量分别为1.14、3.16和6.11 L/min时,水箱的火用效率分别为85.9%、90.7%和83.9%。     

高温相变胶囊梯级储热系统实验研究北大核心CSCD

中高温相变储热及再利用的方式是低碳经济与工业生产的有效手段。为了更高效地实现工业高温废热的利用,本工作设计搭建并测试了一套高温相变胶囊梯级储热系统,采用了两种不同相变温度的多元碳酸盐材料作为储热材料,对换热工质空气的不同进口温度和进口流量的储放热过程进行了实验研究,研究内容主要包括储热罐中的温度变化、储热量以及储放热过程完成时间。实验结果表明在进口温度为500℃的工况下,系统的储热量可以达到30000 kJ,系统进口流量的提高会缩短储热时间,对系统总储热量影响较小,并分析了不同工况下储热罐体内相变材料平均液相率对系统总储热量的影响。同时测试发现系统中设置的空气预热器使得系统的高温尾气与常温进气进行热量交换,可以有效实现高温尾气的余热利用。相变实验的研究结果为高温相变储热技术的实际应用提供了系统运行参数的影响规律和优化准则,具有很高的参考价值。     

A numerical investigation into the charge behaviour of a spherical phase change material particle for high temperature thermal energy storage in packed beds

基于高温相变材料,对填充床储热系统中储热单元球体的储热性能进行了模拟研究.研究了不同传热流体温度和球体直径对球体储热性能的影响规律,对导热为主的相变储热过程与导热和自然对流共同作用的相变储热过程进行了比较分析,同时还探讨了高温辐射换热的影响.结果表明,相变时间随球体直径的增大而增大,随传热流体温度的增大而减小.当考虑相变区域自然对流时,总的相变时间显著减少,和单纯导热相比,完全相变时间缩短了近16%.在导热和自然对流的基础上加上辐射传热后可以看出,辐射换热强化了球体内的传热过程,加快了相变材料的熔化速度,强化了自然对流的作用.     

套管式相变储热单元强化换热数值研究

建立套管式相变储热单元的二维模型,采用ANSYS FLUENT软件模拟分析了换热流体(HTF)侧Re和填充系数λ对储热单元传热性能的影响,采用有效储能比Est来表征相变储能单元的有效储能容量,在此基础上研究HTF侧增强传热对套管式相变潜热储能系统性能的影响.研究结果表明:随着Re从250增加至1 000,熔化时间从22...     

相变蓄热单元蓄/放热过程的数值模拟研究

建立同心套管相变蓄热单元的二维模型,并与文献对比验证,完成网格无关性和时间步长独立性验证后,数值模拟分析模型结构和流体入口速度对蓄热特性的影响,探究导热系数和相变材料的熔点对放热特性的影响。研究结果表明:采用波节管代替光管可优化蓄热单元的蓄热特性,且3#波节管的换热性能最优,相比于光管,蓄热时间可缩短39%;其他条件不变时,增加传热流体(heat transfer fluid,HTF)的导热系数,蓄热单元的放热效率先增后降,存在最佳值;当相变材料(phase change materials,PCM)的导热系数大于HTF时,继续增加PCM的导热系数会使放热效率下降;随着PCM熔点的增加,有效放热时间先增后减,在熔点为603 K时,放热效率达到最大值0.82。     

建立和完善我国石油战略储备的探析

石油战略储备直接影响国民经济。与国家政治和军事也密切相关。介绍了我国石油战略储备目前存在的储备基地选址过于集中、储备方式单一、储备体系不够完善、缺乏与石油储备相关的法律法规以及储备资金来源单一等问题。分析了美国、日本和德国石油战略储备的先进经验。包括储备规模、储备布局、储备模式和管理体制、储备立法以及储备资金来源等方面,将我国石油储备现状与国际先进经验结合分析。对我国石油储备提出了合理确定石油战略储备规模、分散储备布局、合理确定储存方式,合理确定石油储备体系,加快与石油战略储备相关的立法工作以及多方面筹集石油战略储备建设资金等建议。     

A review of large‐scale electrical energy storage

This paper gives a broad overview of a plethora of energy storage technologies available on the large‐scale complimented with their capabilities conducted by a thorough literature survey. According to the capability graphs generated, thermal energy storage, flow batteries, lithium ion, sodium sulphur, compressed air energy storage, and pumped hydro storage are suitable for large‐scale storage in the order of 10's to 100's of MWh; metal air batteries have a high theoretical energy density equivalent to that of gasoline along with being cost efficient; compressed air energy storage has the lowest capital energy cost in comparison to other energy storage technologies; flywheels, super conducting magnetic storage, super capacitors, capacitors, and pumped hydro storage have very low energy density; compressed air energy storage, cryogenic energy storage, thermal energy storage, and batteries have relatively high energy density; high efficiencyin tandem with high energy density results in a cost efficient storage system; and power density pitted against energy density provides a clear demarcation between power and energy applications. This paper also provides a mathematical model for thermal energy storage as a battery. Furthermore, a comprehensive techno‐economic evaluation of the various energy storage technologies would assist in the development of an energy storage technology roadmap. Copyright © 2015 John Wiley & Sons, Ltd.     

Energy storage in the UK electrical network: Estimation of the scale and review of technology options

This paper aims to clarify the difference between stores of energy in the form of non-rechargeable stores of energy such as fossil-fuels, and the storage of electricity by devices that are rechargeable. The existing scale of these two distinct types of storage is considered in the UK context, followed by a review of rechargeable technology options. The storage is found to be overwhelmingly contained within the fossil-fuel stores of conventional generators, but their scale is thought to be determined by the risks associated with long supply chains and price variability. The paper also aims to add to the debate regarding the need to have more flexible supply and demand available within the UK electrical network in order to balance the expected increase of wind derived generation. We conclude that the decarbonisation challenge facing the UK electricity sector should be seen not only as a supply and demand challenge but also as a storage challenge.     

虚实耦合动态货位实施方法

为了解决定置定位库位管理方式库位利用率较低的问题,对动态货位管理方式进行了研究,建立了虚实耦合动态货位模型。实施结果表明,虚实耦合动态库位不仅能够提升库位利用率,还能避免传统动态库位对系统的高依赖性,规避断电风险。     

Potential analysis of hydrogen storage systems in aircraft design

The substitution of fossil fuels with renewable energy sources such as hydrogen is a decisive factor in making aviation environmentally compatible. A key parameter for the use of hydrogen is the storage system. In the design of a flight-capable storage system, not only the mass but especially the volume of the hydrogen has to be considered. Therefore, in this paper different techniques are compared and evaluated from the point of view of their application in aircraft design. The analyses are performed on two reference aircraft, the Airbus A320 and the Embraer E 190, in the short- and medium-haul range. Simplified, it is assumed that the respective max. Take-off mass (MTOM) remains constant. The change of the necessary periphery has no influence on the MTOM. A tank concept could be designed, which can find applications in today's conventional aircraft design.     

关于中国石油储备体系

第二次世界大战以来,石油取代煤炭成为基础能源,目前,已占全球能源消费量的50％以上,这种特殊商品影响着世界的方方面面。一个国家的石油安全涉及这个国家石油资源的拥有量及勘探能力,开采及加工能力,运输及保障能力,安全储备能力等诸多因素。其中,建立科学完备的石油储备体系是保障石油安全的核心环节和重要步骤。     

大规模储能系统发展现状及示范应用综述简

介绍了储能技术分类及其在电力系统的作用,比较全面地阐述了机械储能、化学储能、电磁储能和相变储能分别在电力系统中的应用研究现状和目前的主要示范应用,论述了储能技术未来发展趋势。     

Industrial scale modelling of the thermochemical energy storage system based on CO2 + 2NH3 ↔ NH2COONH4 equilibrium

The thermochemical storage of energy by the system carbon dioxide, ammonia and ammonium carbamate is studied in detail. In particular, the kinetics and the thermodynamics of the reversible reaction is studied. We give two industrial models for the operation of this system. In the first, the separation of the gases NH₃ and CO₂ is achieved by compression and liquefaction of NH₃. In the second, a method of separation of the gases is proposed which is based on the solubility of NH₃ in ethanol while CO₂ is practically insoluble. The operation of this system is examined both in closed form and in the case in which CO₂ is rejected in the atmosphere, and it is taken from alcoholic fermentation or from the combustion gases of power plants burning lignite. The mass and energy balance is given, for each case, and the amount of energy losses by the use of this storage system is calculated. Finally, we give some estimates for the area of solar collectors and the amount of chemicals which are required in order to cover the energy needs of a community.     

Direct contact PCM–water cold storage

Comfort cooling demand continues to increase throughout the world. Conventional cooling production results in high demand for electrical power during peak hours, leading to high emissions for producing cooling, and potential power shortages in electric grids. With a cold storage, the peak power demand is effectively managed and enables free-cooling. This paper examines one concept using phase change materials (PCM) for storing of cold, where the cold carrier (water) is in direct contact with the PCM. This is in order to enable high power for charging and discharging while providing a high storage capacity. A theoretical model highlights important design parameters for reaching large storage and power capacity. The capacity increases with the Packing Factor and temperature difference across the storage. For high power, the flow rate, temperature difference, and drop size is important parameters which is also verified in an experimental evaluation. The obtainable power is between 30 and 80 kW/m³ storage. Practical limitations of this concept are shown to be PCM–water bed expansion and non-uniform channeling due to asymmetric and unstable PCM shells.     

储能技术发展概况研究

我国能源建设面临的主要问题有人均能源储备量少,能源开发利用设备和技术落后,环境污染严重等。因此,研究价值高、应用前景广阔的储能技术,已受到科技界和企业界的密切关注,成为国际能源界研究的热点之一。储能方式主要有物理储能、化学储能、电磁储能和相变储能四大类型,其中物理储能包括抽水蓄能、压缩空气储能、飞轮储能及高温熔岩等;化学储能包括铅酸、锂离子、钠硫和液流等电池储能;电磁储能包括超级电容储能、超导储能和超级电池;相变储能包括蓄热和蓄冷储能等。对储能技术进行分类介绍,对其工作原理、技术现状、发展前景及优缺点进行了讨论,为进一步研究储能技术提供参考。