镁-氢化镁热化学蓄热系统数值分析

蓄热系统是解决热量供需不匹配的有效方式之一。根据热量储存原理的不同,可以将系统分为显热、潜热和热化学蓄热三种类型,其中热化学蓄热有其独特的优点。基于镁-氢化镁热化学蓄热系统蓄放热时的物理化学过程,建立了系统的二维非稳态数学模型,考虑了不同边界条件对系统的影响,通过数值计算,获得了系统的温度、反应速率、反应进度分布及系统的对外放热功率。研究结果表明:系统的蓄热密度为0.85 kW·h·(kg Mg)^-1,热量的传递是影响系统蓄放热效率的关键因素之一,并且当边界对流传热系数保持一定时,存在一个最佳的外界流体温度,使系统的平均放热功率达到最大。在系统以定壁温为边界条件时,系统最大的平均放热功率/质量值为0.79 kW·(kg Mg)^-1。     

基于金属氢化物固态氢源的氢燃料电池动力系统特性的研究

以基于金属氢化物的固态储氢技术，与质子交换膜燃料电池(PEMFC)耦合，搭建了基于金属氢化物固态氢源的氢燃料电池动力系统试验台，测试了吸氢压力、放氢温度、氢流量等关键操作参数对氢燃料电池动力系统性能的影响。结果表明，当吸氢压力大于等于0.60 MPa时，固态储氢反应器放氢流量稳定的时间最长可达4500 s以上。当放氢温度大于60℃时，储氢反应器能完全释放氢气，且放氢时间基本相同。放氢流量越小，氢燃料电池动力系统稳定工作的时间越长。     

Conceptual design of ammonia‐based energy storage system: System design and time‐invariant performance

Chemicals‐based energy storage is promising for integrating intermittent renewables on the utility scale. High round‐trip efficiency, low cost, and considerable flexibility are desirable. To this end, an ammonia‐based energy storage system is proposed. It utilizes a pressurized reversible solid‐oxide fuel cell for power conversion, coupled with external ammonia synthesis and decomposition processes and a steam power cycle. A coupled refrigeration cycle is utilized to recycle nitrogen completely. Pure oxygen, produced as a side‐product in electrochemical water splitting, is used to drive the fuel cell. A first‐principle process model extended by detailed cost calculation is used for process optimization. In this work, the performance of a 100 MW system under time‐invariant operation is studied. The system can achieve a round‐trip efficiency as high as 72%. The lowest levelized cost of delivered energy is obtained at 0.24 $/kWh, which is comparable to that of pumped hydro and compressed air energy storage systems. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1620–1637, 2017     

基于分时电价的区域管网系统储能应用研究

区域供冷系统主要分为源、网、用户三部分，其中管网不仅可以作为能量输送环节，还可以实现能量的储存，因此可以利用管网的储能效应实现制冷站与电网的互动。以广东惠州某园区制冷站为例，基于Modelica语言在Dymola平台上搭建了区域供冷系统。基于分时电价，应用管网的储热与延迟特性，提出三种控制策略以探讨热网在电力响应中的应用。仿真结果显示，在案例中管网储热维持室温的效果为0.31 h，利用管网储热能够使供冷系统节省6.4%的电耗和6.7%的电费，可见管网的虚拟储能效应是制冷站参与电网需求响应的重要资源。     

考虑周期划分特性和储能电池生命周期费用的混合供电系统优化

在风/柴/储混合供电系统中,风力发电的不确定性和用户负载的波动性对混合供电系统及其储能电池系统的优化设计和运行具有重要影响。针对混合供电系统,采用k-均值周期划分法考虑风力发电和用户负载的波动性,建立了混合供电系统及其储能电池系统的优化模型。在优化模型中将储能电池生命周期费用作为惩罚函数,将循环次数作为约束,以标准化能源费用为目标对混合供电系统进行优化,分析了风力发电不确定性对混合供电系统优化设计的影响。以能量需求为793 kW·h·d^-1的风/柴/储混合供电系统为例,研究了混合供电系统优化设计方法。研究表明,考虑风力发电和用户负载的周期划分后,储能电池系统循环次数显著降低,有利于储能电池使用寿命的延长。按风速特性划分周期时,储能电池系统的年循环次数最少,混合供电系统的标准化能源费用最低。当储能电池在其生命周期内的最大循环次数由2000次提升到10000次时,混合供电系统的标准化能源费用降低幅度可达8.3%~16.6%。     

Graphite foams infiltrated with phase change materials as alternative materials for space and terrestrial thermal energy storage applications

In this work, a numerical study is proposed to investigate and predict the thermal performance of graphite foams infiltrated with phase change materials, PCMs, for space and terrestrial energy storage systems. The numerical model is based on a volume averaging technique while a finite volume method has been used to discretize the heat diffusion equation. A line-by-line solver based on tri-diagonal matrix algorithm has been used to iteratively solve the algebraic discretization equations. Because of the high thermal conductivity of graphite foams, the PCM-foam system thermal performance has been improved significantly. For space applications, the average value of the output power of the new energy storage system has been increased by more than eight times. While for terrestrial applications, the average output power using carbon foam of porosity 97% is about five times greater than that for using pure PCM.     

Ausgleich der Volatilität der Erneuerbaren Energien mittels Wärmespeichern auf Salzbasis

To compensate for the volatility of renewable energies, solutions beyond fossil reserve power plants are needed. One approach is salt-based heat storage with phase change materials (PCM). In order to achieve economic efficiency, ambitious targets are required. A sensible and latent heat storage system for the temperature range around 400 °C based on salts and thermal oils with high development potential is presented.     

Design of a small solar-powered desalination system

A design is presented for a solar/thermal system configured to power a reverse osmosis (RO) desalination unit to produce 7000 gallons of fresh water in an eight hour period. A field of line-focus tracking solar collectors is used to heat a high pressure liquid-vapor water storage tank supplying two compound reciprocating steam engines, one direct-connected to the RO high-pressure pump and the other to an electric generator for auxiliary power. An auxiliary heating loop with an oil-fired boiler is also used to supply the steam engines.The system operates in either all-solar, all-oil, or mixed solar/oil modes. Primary operating mode is assumed to be a mixed solar/oil mode in which the oil-fired boiler is used only to prevent shutdown of the RO system during the course of a partly sunny day. In this mode, the RO system does not come on line in the morning until the solar collector field has brought the high-pressure storage tank to a point near maximum operating pressure. Thereafter, the oil-fired boiler comes on automatically whenever the storage tank is drawn down to a pressure near minimum full-power operation (due to inadequate or intermittent insolation) and remains on, supplying the steam engines, until the solar collectors have again brought the storage tank to the high-pressure cutoff.In the all-solar mode, the system continues to operate at reduced power as storage tank pressure drops below the point at which the oil-fired boiler would otherwise come on. A portion of the RO system is shut down to maintain pressure in the remainder.The all-oil mode is used whenever fresh water is required during non-sunny periods, or to increase fresh water production in sunny periods.     

太阳能热化学储能研究进展

太阳能热发电技术对缓解全球资源紧张和改善环境有广阔的应用前景,大规模高温无损储热是太阳能热发电系统的关键。本文通过对显热储能、潜热储能和热化学储能3种热能储存方式的比较,认为热化学储能方法由于储能密度高,且可长期在环境温度下无热损储存,因而为太阳能热发电中的高温热能储存提供了一种潜在的方法。并对热化学储能在太阳能热力发电的应用上进行了技术经济分析,综述了几种有前景的热化学储能体系的研究进展,总结了各种储能体系的现存问题。根据热化学储能方法在实用化过程中存在的技术经济问题,指出了热化学储能技术的未来研究方向是储能反应器的设计、能量储存/释放循环性能探究、储能体系的选择及热化学储能系统的中试放大研究等。     

Kinetics and flow of diallyl phthalate resins

The analysis of molding operations for thermosetting polymers requires knowledge of the rheology and reaction rates of the materials. The purpose of this research was to measure kinetic and rheological data on diallyl phthalate resins and to integrate these results into models describing the flow behavior. The chemical kinetics of the curing reactions were derived from calorimetric measurements taken with a differential scanning calorimeter. The rheological data were measured with a mechanical spectrometer equipped with eccentric rotating discs. A model based on the theory of ideal rubber elasticity was used to correlate the elastic storage modulus with reaction time and temperature. For the region below the gel point, the dynamic viscosity exhibited a power law dependence on angular frequency and an Arrhenius dependence on temperature.     

Hybrid energy storage system based on supercapacitors and Li-ion batteries

Energy storage systems (ESS) have a wide spectrum of functions. They must provide power quality, shaving of load change, coordination of distributed power systems, bulk energy storage, and end-user reliability, e.g., uninterrupted power supply. In present paper the configuration and design of experimental ESS based on both Li-ion batteries and supercapacitors have been proposed. Such a hybrid energy storage system (HESS) includes three main components: Li-ion batteries, supercapacitors, and grid interconnection consisting of two invertors and control and monitoring system. Energy storage capacity of developed HESS prototype is 100 kWh, nominal power—100 kW, peak power—200 kW. HESS was created and tested within the experimental facility also including 1.5 MW gas turbine power plant, 200 kW controllable active and reactive loads, and control and measurement system. Experimental results showed that HESS successfully provides the following advantages: (i) suppression of voltage, current, and frequency disturbances in the grid; (ii) compensation of reactive power in the circuit; and (iii) uninterrupted power supply. Cost analysis of proposed hybrid system has also been carried out. In comparison with battery ESS without supercapacitors, HESS showed longer life time, lower cost, and higher peak power.     

平抑电耗波动的热泵蓄热-供热系统优化

针对办公建筑物昼夜热负荷需求存在差异,从而导致热泵供热系统一天内电力供给需求波动较大的问题,本文构建了平抑电能消耗波动的热泵蓄热-供热系统,并提出了对应的优化运行策略。以热泵蓄热-供热系统耗电功率稳定及耗电成本最低作为优化目标函数,对蓄热和供热参数进行了优化分析。基于天津地区气象参数,根据某9000m²办公楼能耗,对所构建的可平抑电耗的热泵蓄热-供热系统进行了优化分析,结果表明：采用热泵蓄热并对运行参数进行优化控制后,系统的谷电电耗增加,峰电负荷降低,实现了供热系统日耗电功率恒定,典型日高峰时段系统耗电功率最大降低50.29%,日间平均耗电功率降低28.10%,全天耗电功率稳定于53.54kW;与无蓄热常规热泵供热系统相比,整个供热期的电耗波动大幅下降,总运行费用降低。     

De- and rehydration of Ca(OH)2 in a reactor with direct heat transfer for thermo-chemical heat storage. Part A: Experimental results

Heat storage technologies are used to improve energy efficiency of power plants and recovery of process heat. Storing thermal energy by reversible thermo-chemical reactions offers a promising option for high storage capacities especially at high temperatures. Due to its low material cost the use of the reversible reaction Ca(OH)₂ ? CaO + H₂O has been suggested. This paper reports on the thermal behavior of a reactor with direct heat transfer between the gaseous reactant and the solid material. Cycling stability is confirmed and the impact of the most significant parameters such as the maximum possible enthalpy difference of the heat transfer fluid between inlet and outlet, the heat transfer, the particle reaction rate and the mass transport is derived. In the test system the particle reaction rate could be identified as the main limiting parameter.     

De- and rehydration of Ca(OH)2 in a reactor with direct heat transfer for thermo-chemical heat storage. Part B: Validation of model

Heat storage technologies are used to improve energy efficiency of power plants and recovery of process heat. Storing thermal energy by reversible thermo-chemical reactions offers a promising option for high storage capacities especially at high temperatures. Due to its low material cost the use of the gas–solid reaction Ca(OH)₂ ? CaO + H₂O has been suggested. In Part A of this work the thermal behavior of a reactor with direct heat transfer was experimentally investigated. In this part a two-dimensional model is applied for the specified system. The experimental and simulated results during the exothermic hydration are discussed in order to confirm the validity of the model. The model is validated regarding heat transfer, integral reaction rate and maximum temperatures. In addition, an adaptation of the kinetic equation is proposed in order to take into account rate-limiting effects due to agglomeration in the powder bed.     

新能源化工技术

发展新能源是实现“碳中和”战略目标的必由之路。本文首先勾画出可再生能源转换利用基本途径,指出新能源化工技术研究的理论基础是电化学工程、光化学工程、生物化学工程、分子化学工程、系统工程和人工智能等;其次,以可再生能源制氢、燃料电池发电与化学品共生、太阳能转换过程为例,阐明可再生能源资源转换中的化工问题;第三,通过对锂离子电池和钠离子电池中多元过渡金属氧化物正极材料及其电极制备过程开发,揭示电化学储能材料与器件制造过程工程特性;第四,介绍了化工系统工程和人工智能在电池状态预测模型构建、综合能源系统管理、光-储-充系统集成与优化运行中的应用。最后,根据各种案例分析,归纳出新能源化工研究的本质是将新能源转换与储存中涉及的“生物/光/电化学反应”,从实验室放大到规模化生产装置,阐明反应中的传质、传热和传荷机理及其反应工程特性。对未来新能源化工技术研发,从“共性科学问题”和“关键技术”两个层面提出了若干研究方向以供参考。     

Modeling a Reversible Solid Oxide Fuel Cell as a Storage Device Within AC Power Networks

A reversible solid oxide fuel cell (RSOFC) system, consisting of a RSOFC stack, heat store, and electrical inverters to convert DC to AC power, is shown by computer modeling to have the potential to efficiently store electrical energy. This paper describes the modeling of a single RSOFC, based on a proposed cell geometry, empirical data on the resistivities of the components, and calculation of activation and diffusion polarization resistances from electrochemical theory. Data from ac impedance spectroscopy measurements on symmetrical cells are used to model RSOFC impedance. A RSOFC stack is modeled by electrically linking the individual cells inside a pressurized vessel. A phase change heat store is added to improve energy storage efficiency. The model is implemented in MATLAB®/Simulink®. Two competing inverter control schemes are compared, trading off DC bus ripple against AC power quality. It is found that selection of appropriate DC bus capacitance is important in certain scenarios, with potential system cost implications. It is shown that the system can store electrical energy at an efficiency of 64% over a single discharge–charge cycle, i.e., hydrogen to electricity and heat to hydrogen.     

智能算法与自寻优在中储式制粉系统中的应用

球磨机是中储式制粉系统的重要设备,它具有运行可靠、维护简单、对煤种适应性广等诸多优点。但由于中储式球磨机制粉系统是一个典型的多变量、强耦合、非线性、大时滞系统,常规的PID控制很难取得满意的效果。本文介绍基于智能算法与自寻优算法相结合的控制策略在动力厂制粉系统中的应用情况。     

钙基热化学储能体系装备与系统研究进展

近年来,由于可持续发展的需要,太阳能等清洁可再生能源的大规模应用被提上日程。为解决太阳能受天气、昼夜等因素影响造成的不能持续稳定供能的问题,许多学者提出将储能系统整合至太阳能发电中,将太阳能热量以某种方式存储起来,需要时释放,从而使系统能持续运转。其中,热化学储能由于能量密度高,材料能够长期稳定储存与运输等优势,成为储能领域中新兴的研究热点。在众多的热化学储能材料中,基于CaCO₃/CaO与Ca(OH)₂/CaO体系的钙基热化学储能系统材料安全性高,成本较低且易于获得,十分具有发展潜力。本文对这两种钙基热化学储能体系的原理与材料进行了简单介绍,综述了该领域先进反应器设计与系统集成控制方面的国内外发展状况,探讨了目前研究面临的挑战与机遇,提出了钙基热化学储能技术的今后研究与发展方向的建议。     

为强化石油回采捕集CO2的全周期评估

The development and deployment of Carbon dioxide Capture and Storage （CCS） technology is a cornerstone of the Norwegian government＇s climate strategy. A number of projects are currently evaluated/planned along the Norwegian West Coast, one at Tjeldbergodden. COe from this project will be utilized in part for enhanced oil recovery in the Halten oil field, in the Norwegian Sea. We study a potential design of such a system. A combined cycle power plant with a gross power output of 832 MW is combined with CO2 capture plant based on a post-combustion capture using amines as a solvent. The captured CO2 is used for enhanced oil recovery （EOR）. We employ a hybrid life-cycle assessment （LCA） method to assess the environmental impacts of the system. The study focuses on the modifications and operations of the platform during EOR. We allocate the impacts connected to the capture of CO2 to electricity production, and the impacts connected to the transport and storage of CO2 to the oil produced. Our study shows a substantial reduction of the greenhouse gas emissions from power production by 80% to 75 g·（kW·h）^-1. It also indicates a reduction of the emissions associated with oil production per unit oil produced, mostly due to the increased oil production. Reductions are especially significant if the additional power demand due to EOR leads to power supply from the land.     

垃圾焚烧发电耦合电转气制备合成天然气工艺集成与优化

垃圾焚烧发电耦合电转气技术制备合成天然气工艺可同时实现温室气体减排和大规模储能。由于垃圾发电效率低和甲烷化反应热利用效率不高,此工艺能效偏低。为了提升工艺能效,本文采用Aspen Plus软件对垃圾焚烧发电耦合电转气制备合成天然气过程进行了全流程模拟,基于能量平衡分析,提出了一种利用甲烷化反应热优化垃圾焚烧发电过程的工艺集成方法。针对这个优化过程,设计了一套由一级绝热固定床反应器和一级低温流化床反应器串联组成的甲烷化工艺。借助绝热固定床反应器出口高温气体提升主蒸汽参数、优化蒸汽循环过程,可将发电效率从22.05%提升至31.72%。流化床反应器低温操作有利于提升合成天然气品质,其内置换热管束作为补充蒸发受热面。此外,还考察了垃圾焚烧炉烟气再循环方式对整体工艺的影响,结果表明采用烟气干循环工艺时能效较高。以上结果对于提升工艺经济性和竞争力具有一定指导意义。