炉烟干燥开式制粉系统的锅炉热平衡及烟气特性计算方法

在当前国内的锅炉相关标准及文献中,均未对炉烟干燥开式制粉系统锅炉的热平衡及热力计算方法予以介绍。本研究提出了开式制粉系统的3种炉烟干燥方案,并对应用这3种炉烟干燥方案的开式制粉系统锅炉的热平衡及烟气特性进行了深入分析,指出了其与传统闭式制粉系统锅炉的区别。继而,基于常规的燃煤收到基分析数据及低位发热量,提出了适用于炉烟干燥开式制粉系统锅炉的热平衡及烟气特性计算方法,据此可完成完整的开式制粉系统锅炉热力计算。该计算方法为炉烟干燥开式制粉系统锅炉的研究、应用及优化提供了理论基础。     

蒸汽凝结水闭式回用的难点分析

蒸汽凝结水的闭式回用是提高蒸汽供热系统热效率的重要措施。目前很多工厂企业都在采用这种技术,取代原有的开式回收系统,但有相当多的企业凝结水闭式回收系统并不成功,有的甚至由于闭式系统的投运,影响了蒸汽换热工艺。本文针对蒸汽凝结水闭式回收系统经常出现的问题,进行分析并提出解决方法。     

开式地表水源热泵系统工程实践若干问题探讨

地表水源热泵系统分为开式系统与闭式系统两种.与闭式系统相比,开式系统换热效率更高,应用更为广泛.城市污水源热泵系统是典型的开式水源热泵系统.本文以其为例介绍了开式地表水源热泵系统实际工程中存在的相关问题及其解决方法.从设备选型、管路设计、热水供应、大型系统应用等方面进行了较为详尽论述,达到了很好的总结及推动该项技术进步的效果.     

化学蓄热系统性能的数值研究

随着能源的日益消耗,对新能源的需求日益增大,因此新能源的利用成为研究的重点。热化学蓄热通过化学反应将太阳能或者工业废热等能量储存起来在需要时使用。文中使用Comsol软件来模拟热化学蓄热系统中的反应器,通过研究加热流体不同进口温度对反应器中温度及浓度的影响来研究加热流体温度对热化学蓄热的影响。     

柴油机曲轴箱强制通风系统的试验研究与开发

在玉柴某型柴油机上,通过装闭式循环强制通风油气分离器与开式循环油气分离器进行对比试验,研究闭式循环强制通风系统对发动机性能的影响.结果表明:加装闲式循环曲轴箱强制通风系统可调节发动机的曲轴箱压力在合理范围内变化;分离效率的高低直接影响到通入增压器压气机进气中含油量的高低.同时解决了开式循环曲轴箱通风系统中柴油机的含油废...     

开式水系统自动排气虹吸补偿应用

叙述引起闭式系统开式循环水虹吸破坏因素及现象，针对某燃气电厂机组运行期间闭式水温高，通过对相关现象和参数的分析，判断为开式水虹吸破坏导致闭式水换热器冷却面积不足，引起闭水温度高，进行了处理并提出了防范措施，通过查阅相关技术文章提出改进现有换热器排气结构，能够让正压管式换热器实现虹吸工作模式下排气，采用具备虹吸模式排气运行的换热器，节能改造有借鉴意义。     

气体机迷宫式油气分离器分离效率的试验研究

针对一款六缸天然气气体机新产品,进行了内置迷宫式油气分离器选型、设计和试验研究。在全负荷、标定转速工况下,油气分离器内部温降约为7℃,相同窜气量时闭式迷宫分离器内部的温度要比开式的低约5℃。分离器的内部压力随窜气量的增大而增大。分离效率随着窜气量的增大而增大,在180L/min时闭式和开式系统都达到约87%的分离效率,而流量小于180L/min时闭式分离系统的分离效率比开式分离系统最高可高出约10%。试验结果表明:分离器内部隔板和挡板结构尺寸和安装距离的优化组合、窜气量的大小、开式油气分离通风系统或闭式油气分离通风系统方案的选择都是影响油气分离器分离效率的关键因素。     

闭式循环柴油机性能的试验研究

在闭式循环柴油机开式运行和闭式运行时,通过改变超重力旋转床的水流量,对吸收器的吸收特性及其闭式循环柴油机性能的影响进行了分析.恒定柴油机负载,改变混合进气中氩气的含量,分析了进气混合气中氩气含量对闭式循环柴油机性能的影响.在闭式运行时进行负荷试验,并与开式对比,对开式运行和闭式运行的油耗、系统压力等参数及柴油机运行状况进行了对比分析.     

安徽安庆电厂发电机与励磁机冷却用水节能改造方案探讨

安庆电厂一期工程2台320MW机组,设计时发电机氢冷器与励磁机空冷器用开式水冷却,经过4年多的运行发现开式水存在弊端。将发电机氢冷器与励磁机空冷器由开式水冷却改为闭式水冷却后,一方面可以提高安全性,另一方面可利用闭式水的废热在冬季提供给集控采暖用与加热补给水等,并就闭式水系统的两种方案进行了技术经济性比较。     

基于海底黑烟囱的海洋温差发电热力循环系统研究

与传统的海洋温差发电系统不同,海底黑烟囱海洋温差发电系统是以海洋地热为热源,以深海冷水为冷源的发电系统。文章分别分析和计算了以水蒸气为工质的开式系统和以纯氨为工质的闭式系统的循环热效率、换热器负荷、泵耗以及循环净功等相关参数。结果表明,与以纯氨为工质的闭式系统相比,开式系统的热水泵功耗过大,降低高温海水的温度和提高闪蒸压力对开式系统是不利的;以水蒸气为动力循环工质有利于降低换热器的负荷,这对换热器的设计是十分有利的。     

Performance analysis of high-capacity thermal energy storage using solid-gas thermochemical sorption Principle

储能技术是提高能源利用效率的一种有效手段,可有效调配能量供给与需求在时间,空间和强度上的匹配关系,传统显热储存技术和相变潜热储存技术的储热密度一般在100~200 kJ/kg,储热能力较低不利于规模化应用.本工作提出一种基于固-气化学反应的大容量热化学吸附储热方法,利用吸附工质对在化学反应过程中热能与化学吸附势能的相关转化实现热量的储存和释放,具有高效储热的显著优点.采用4种典型温区的吸附储热工质对为例进行了热化学吸附储热热力循环特性及工作性能的理论研究,在此基础上对不同温区吸附储热工质对(50~280 ℃)的热化学物性参数,储热温度,储热密度进行了分析比较,以期实现不同温度品位的热量储存.结果表明:热化学吸附储热技术的反应盐储热密度高达2000 kJ/kg以上,其储能密度约为传统显热储存技术和相变潜热储存技术的10~20倍,是一种具有发展潜力的大容量,高性能储热方法,该新技术可为规模化工业储热应用及太阳能等可再生能源的高效利用提供技术支撑.     

EXERGY ANALYSIS OF AMMONIA-BASED SOLAR THERMOCHEMICAL POWER SYSTEMS

The reversible dissociation of ammonia is one of the candidate reactions for use in closed loop solar thermochemical energy storage systems. The major determinant of achievable performance for such a system is the degree of thermodynamic irreversibility associated with the heat recovery process. Exergy analysis of a semi realistic 30 MPa isobaric system has revealed that the major irreversibilities occur within the exothermic reactor and the counterflow heat exchanger between ingoing and outgoing reactants. In this study, optimum reactor control yielded exergetic efficiencies up to 71%, which should translate to overall solar to electric conversion efficiencies of around 20%.     

Five Solar-Energy Desalination Systems

This paper gives an overview of the Solar Energy Storage Program at the Solar Energy Research Institute. The program provides research, systems analyses, and economic assessments of thermal and thermochemical energy storage and transport. Current activities include experimental research into very high temperature (above 800^°C) thermal energy storage and assessment of novel thermochemical energy storage and transport systems.

The applications for such high-temperature storage are thermochemical processes, solar thermal-electric power generation, regeneration of heat and electricity, industrial process heat, and thermally regenerative electrochemical systems.

The research results for five high-temperatuTe thermal energy storage technologies and two thermochemical systems are described.     

Thermodynamic limits on the performance of a solar thermochemical energy storage system

Use of closed-loop thermochemical energy storage systems for the storage of solar energy places fundamental limits on the amount of work which can be extracted from the recovered energy. These arise because of thermodynamic irreversibilities associated with the storage system itself and because of the need to degrade collected solar energy to the characteristic temperature of the reaction system chosen. General expressions for the exergetic and work recovery efficiencies of thermochemical storage systems have been developed by assuming that the reaction process is the only source irreversibility within the closed-loop system. These have been used to plot contours of constant efficiency for the ammonia-based thermochemical system. The effect of spontaneous separation of mixtures due to the preferential condensation of ammonia has been examined analytically and graphically. The analysis presented represents a necessary prerequisite for the optimization of system efficiencies by reactor design.     

Experimental and numerical analysis of seasonal solar‐energy storage in buildings

This paper presents seasonal‐energy storage of solar energy for the heating of buildings. We distinguish several types of seasonal storage, such as latent, sensible, and chemical storage, among which the thermochemical storage is used and analysed in this research. In the first part, a laboratory heat‐storage tank, which was made in the laboratory for heating, sanitary, and solar technology and air conditioning from the Faculty of Mechanical Engineering, University of Ljubljana, Slovenia, was presented. The experimental model was tested for charging and discharging mode. Two types of numerical models for sorption thermal‐energy storage exist, which are microscale and macroscale (integral). For microscale analysis, the analysis system (ANSYS) model can be used to simulate the behaviour in the adsorption reactor. On macroscale or integral scale, TRaNsient SYStem (TRNSYS) model was used to perform the operation of the storages on the yearly basis. In the second part the simulation of the underfloor heating system operation with a built‐in storage tank was carried out for two locations, Ljubljana and Portoro?. Furthermore, the comparison between a thermochemical and sensible‐heat storage was performed with TRNSYS and Excel software. In this comparison, the focus was on the surface parameters of the SCs and volume of the thermal‐storage tank for the coverage of the energy demand for selected building. With this analysis, we would like to show the advantage of the thermochemical storage system, to provide greater coverage of the energy demand for the operation of the building, compared with the seasonal sensible‐heat storage (SSHS). Such a heat‐storage technology could, in the future, be a key contributor to the more environmentally friendly and more sustainable way of delivering energy needs for buildings.     

The efficiencies of thermochemical energy transfer

A general thermodynamic study of thermochemical energy transfer and work production processes is presented. Both gaseous systems in which the effluent of each reactor is not separated into the reactant and product species, and liquid/gas systems in which the effluent separates spontaneously into liquid and gas phases, are treated. the study extends to consideration of non-isothermal reactors, to the individual roles of reactor and heat exchanger in the work production processes and to the significance of the intrinsic work of phase separation. the overall system efficiency is derived as the product of two efficiencies: the energy storage efficiency which defines the fraction of the input energy passed in chemical form to storage and the work recovery efficiency which defines the fraction of this stored energy available as output work. the fundamental thermodynamic processes underlying the derivation of these efficiencies are examined from the point of view of optimization of the design and operation of individual system components. In particular, it is shown that the available work from a thermochemical energy transfer system approaches the maximum value given by the Gibbs' free energy change when the temperature profile of the exothermic reactor is suitably tailored. The work of separation has formed the basis of the analysis of specific system components and has given a useful insight into the understanding of energy storage efficiency. Work recovery efficiencies are calculated for the ammonia/hydrogen-nitrogen system and the paper concludes with a discussion of some practical considerations relating to the recovery of work and the performance that one might ultimately expect from this system.     

太阳能热化学能量贮存与转化研究

分析了以氨为工质对闭式循环工况下太阳能量收集、贮存、恢复转化过程,建立了闭式太阳能热化学反应热力循环过程二维均质催化反应传热传质数学模型,并对模型计算中相关参数的选择进行了分析说明.太阳能可逆化学反应能量贮存与转化过程可有效地结合到太阳能热力发电及空调制冷之中,解决太阳能量传输受气候间隙性的影响.     

Solar-heated rotary kiln for thermochemical energy storage

Thermal energy storage (TES) will improve the efficiency and output of solar power plants. TES based on thermochemical cycles is an interesting option as thermochemical cycles can provide high energy storage densities and allow longer heat storage time. The use of multivalent solid oxide reduction–oxidation (REDOX) reactions for thermochemical heat storage is a promising option. Several concepts are feasible for coupling solar energy to the redox reaction. Among those a directly irradiated rotary kiln is one of the most interesting because it is able to provide high mass flow rates and high amounts of active material. A solar-heated rotary kiln was set-up and operated in the solar furnace of DLR for thermal reduction and oxidation of cobalt oxide. The redox material was fed into the reactor batch wise and reduced on-sun at temperatures of about 900 °C and re-oxidized off-sun in the same rotary kiln. Both steps were carried out in an air atmosphere. Thirty cycles were performed with one batch showing no evident degradation of the material. The results confirm that the rotary kiln is a feasible reactor set-up for the solar reduction of metal oxides and, hence, for thermochemical energy storage.     

Thermal performance of a two-phase thermosyphon energy storage system

This article presents an energy storage system, which can be readily integrated with the building structure. It stores heat supplied by solar energy via the two-phase closed loop thermosyphon to storage tank and releases stored heat in energy storage material via two-phase closed thermosyphon to the heat exchanger through the flow of transport fluid. The functions of such energy storage system have three operating modes, i.e., heat charge, heat discharge, and simultaneous charge and discharge. The thermal performance of the system with alcohol and water as working fluid is experimentally investigated. The results show that the storage system employing alcohol as working fluid in the loop thermosyphon provides better performance; the system gives optimum heat charge and discharge performance under 35–40% fill ratio, regardless whether the working fluid is water or alcohol. The system displays optimum charge efficiency of 73% and optimum discharge efficiency of 85% with alcohol as working fluid.