用于高温气冷堆发电设备的闭式循环氦气轮机装置

对HTGR-CT发电装置中的氦气轮机装置作了简要介绍．叙述其循环、工质以及影响循环效率的关键因素,并分析HTGR-CT发电装置布雷顿循环系统当前和近期的参数值。针对氦气轮机装置,论述了涡轮、压气机、热交换器、转子、轴承和热氦气管道等主要部件的设计和结构特点,并简要介绍了应用于氦气轮机的材料。最后指出在开发HTGR-CT发电设备中要重视两个关键技术问题：一是开发出用于大功率机组的安全、可靠的磁性轴承;二是免除放射性污染能进行安全运行和有效维护的问题。     

闭式氦气轮机循环建模及循环特性优化分析

氦气闭式布雷顿循环可用作高温气冷堆热电转换装置，能够有效降低传统核电机组复杂程度，提升热电转换效率。为详细研究氦气闭式布雷顿循环特性，指导工程样机设计，基于Refprop提供的真实气体模型建立了简单、间冷、回热以及间冷-回热四种闭式布雷顿循环数学模型；然后通过对比分析方法，揭示了关键参数变化对循环特性的影响，重点阐述了间冷、回热器对循环性能的作用机制：1)回热器能够有效回收涡轮出口氦气热量，大幅提升循环热效率，并且能够降低系统达到最佳循环效率所需压比；2)使用间冷器虽然能够降低压缩系统功耗，但受间冷器流道内压损影响，需综合考虑系统复杂度、研制成本及循环性能等因素确定系统是否需要间冷器。     

氦气涡轮一维特性预估方法研究

为探究以氦气作为闭式布雷顿循环动力系统工质的涡轮特性,基于氦气与空气的物性差异对损失模型进行修正,绘制涡轮特性曲线,构建一种特殊工质轴流透平一维特性快速预估方法,并通过三维仿真进行验证。研究表明：对损失模型进行修正后,一维预估得到的特性参数更加接近CFD计算结果;在设计点工况下,总温比的误差由0.53%降为0.42%,等熵效率的误差由7.8%降为0.23%;在非设计工况（50%,70%,100%设计转速）下,特性预估结果也较为准确。该方法可实现氦气涡轮特性快速预估,减少计算量。     

氦气轮机高温气冷堆(GT-HTGR)

氦气轮机高温气冷堆(GT-HTCR)就是在一回路直接采用氦气闭式循环燃气轮机(CT)的高温气冷核反应堆(HTGR)；氦气既是核反应堆的冷却剂，又是闭式循环燃气轮机的工质；这个闭式循环燃气轮机通常由高、低压压气机、涡轮、预冷器、间冷器、回热器组成，并采用电磁轴承。选择氦气为工质，是因为氦气具有很高的比热和导热系数，同时又是惰性气体。     

高温气冷反应堆核电站紧凑型热交换设备的设计和研究

正据《Теплоэнергетика》2013年7月刊报道,核电站的建造最优先考虑发电的高效率(约50%)。在这方面,配备氦气轮机装置和氦气载热介质高温反应堆的核装置很有前途。机械制造设计局的专家对高温气冷反应堆核电站紧凑型热交换设备进行了成功的设计和详细的研究。将高温气冷反应堆和氦气轮机装置一起组成一回路的核电站设计必须以利用氦气循环高效的热交换设备为先决条件。提供了最佳热交换表面选择的分析和计算-试验研究的结果。并分析研究了回热器、端部冷却器和中     

分层热物性测试在热泵工程的应用分析

以工程场地测试孔内岩土体垂直分布的热物性参数为研究对象。在传统热物性测试仪器中加入分布式光纤测温系统,进行岩土体初温测试和热物性测试,测定不同深度岩土体初温和加热试验中不同深度循环流体平均温度,并与传统测试结果进行对比分析。结果显示,分层热物性测试结果较为准确,可分析岩土体垂直方向温度分布,进而得出地埋管换热器在垂直方向上导热系数和传热系数。     

高温气冷堆氦气轮机性能的初步研究

结合了模块式高温气冷堆与气体透平循环技术的高温气冷堆氦气轮机循环是核电领域中的全新概念,为高核电的安全性和经济性提供了新思路,具有很强的竞争优势。首先对高温气冷堆氦气轮机进行了初步研究,表明氦气轮机叶片级数多,叶片高度低。然后应用商业软件NUM ECA对平面叶栅在相同的进出口条件下分别以氦气和空气为工质进行了二维数值模拟计算,并进行了流场分析,揭示了氦气轮机与燃气轮机的区别。     

小型离心式压气机压缩氦气闭式循环的初步研究

介绍了小型离心式压气机闭式循环实验台的组成,并在此实验台上进行了压缩氦气和压缩空气闭式循环的实验,针对实验所得数据进行整理和理论分析,得到了压气机压缩氦气的特性线,并且利用压缩空气和压缩氦气的对比实验结果,初步分析了同一压气机压缩不同工质的相似现象。     

回热器孔隙率对VM循环热泵性能的影响分析

孔隙率是表征回热器结构和效率的重要参数,影响整个系统的流动和传热特性。以热驱动斯特林循环的VM(Vuilleumier,维勒米尔)循环热泵为研究对象,建立了其内部回热器的模型,研究了在不同的热源温度、系统压力、转速、容积比和工质的情况下,孔隙率对整个热泵系统性能的影响。结果表明：随着孔隙率的增加,系统性能系数先增加后减小,在0.6左右达到最佳。在相同孔隙率的情况下,系统性能系数随着热源温度、系统平均压力、容积比、转速的增加而分别增大,并且增加的幅度是越来越小的。对于工质而言,氦气和氢气的性能较优,而氮气的性能较差。综合考虑安全等因素,宜选氦气作为工质。     

基于He-N2混合工质的闭式Brayton循环系统及设备的优化设计

对以He-N_2混合气体为工质的闭式Brayton循环系统进行了优化分析,获得循环最高效率下系统各组成设备的性能参数。以此优化结果为目标,设计了轮机和换热器的初步方案。以纯氦气工质时轮机和换热器的成本为基准,利用设备成本与几何参数之间的近似关系,获得不同氦气摩尔分数下轮机和换热器的相对成本。通过Brayton循环中轮机与换热器的成本权重分配,得到不同氦气摩尔分数下Brayton循环的相对总成本。结果表明:当氦气摩尔分数为50%～60%时,存在一个相对总成本的最小值,与纯氦气时相比,其相对总成本降低了12%左右,这对于闭式Brayton循环系统工质的选择具有一定的指导意义。     

Food thermophysical property models

The design engineer must predict the thermophysical properties of foods in order to design food storage and refrigeration equipment and estimate process times for refrigerating, freezing, heating or drying of foods. Since the thermophysical properties of foods are strongly dependent upon chemical composition and temperature, composition based models provide a means of estimating these properties. Numerous models of this type have been proposed and the designer of food processing equipment is thus faced with the challenge of selecting appropriate models from the plethora of those available. This paper describes selected food thermophysical property models and evaluates their performance by comparing their results to experimental thermophysical property data. The results given in this paper will be of value to the design engineer in the selection of appropriate food thermophysical property models.     

利用Delphi和Access实现对溴化锂水溶液热物性数据的可视化查询

通过对Access2003数据库基本结构的分析,介绍了利用Delphi访问建立在Ac-cess2003上的物性数据库的方法,并实现了对溴化锂水溶液热物性数据的可视化查询。     

Natural convection due to horizontal temperature and concentration gradients—1. Variable thermophysical property effects

Typically for single component fluids, the variation of thermophysical properties is negligible except in the presence of large temperature differences, and, therefore, has no appreciable effect on the heat transfer. In contradistinction, thermophysical properties can vary significantly due to concentration differences which affect the heat and mass transfer. This work examines the effects of thermophysical property variation on the heat and mass transfer in a cavity due to natural convection driven by combined thermal and solutal buoyancy forces. Results indicate that thermophysical property variations can appreciably influence heat and mass transfer and velocity distribution.     

Experimental investigation on subcooling of liquid hydrogen by helium gas injection through evacuation

Subcooling is the process of bringing down the temperature of liquids lower than that of the boiling point of the corresponding vapor pressure. The performance of subcooling of cryogenic liquids mainly depends on the heat-inleak of the system, the helium injection mass flow rate, helium injection temperature, and helium injection nozzle pattern. This paper presents an alternative method, by making use of the least heat in the leakage of the liquid hydrogen storage container, which is quite possible because containers with excellent thermal insulation are commercially available nowadays. The process involved is rapid evacuation through gas ejectors, thus reducing the effect of temperature. The advantage and the process of evacuation leading to subcooling in a unique manner are the objective of this article. The experimental results are discussed in comparison with the thermophysical process involved in the subcooling operation. A comparative study is also carried out with the theoretical heat exchange process in which helium is used as a medium for the economy of the stated process. It is stated that the current process of subcooling through evacuation is superior to the conventional heat exchange process.     

Effects of superheat and temperature-dependent thermophysical properties on evaporating thin liquid films in microchannels

A model based on the augmented Young–Laplace equation and the Clausius–Clapeyron equation was developed to describe the extended evaporating meniscus in a microchannel. The effects of the adsorbed film thickness, channel height and temperature-dependent thermophysical properties of the fluid are included in the model at wall superheats up to 50 K. The liquid flow is coupled with the vapor flow to obtain the mass transport across the liquid–vapor interface. The results show that the constant thermophysical property model greatly overestimates the liquid pressure difference and the total thin film heat transfer rate at higher superheats compared with the variable thermophysical property model. The adsorbed film thickness, which is controlled by the disjoining pressure limit, reaches a minimum near about 20 K superheat for water. The maximum film curvature and liquid pressure difference then decrease at superheats larger than 20 K. The effects of the capillary pressure limit produced by the channel height can be reduced by increasing the superheat.     

Thermophysical Properties of a New Environment Friendly Alternative—Trifluoroiodomethane

Trifluoroiodomethane (CF₃I) is considered as a promising refrigerant alternative, especially as a component in mixtures, to replace CFC-12. But reliable thermophysical property data for CF₃I are still limited. The investigations on thermophysical properties of CF₃I developed by us are summarized in this paper. Experimental data of critical parameters, and the correlations of saturated liquid and vapor density, enthalpy of vaporization, vapor pressure, PVT properties, second virial coefficient, ideal-gas heat capacity, surface tension, viscosity and thermal conductivity are given in the present paper.     

变物性对有凸出热源通道换热计算的影响

本文基于一侧含有三个均匀分布的凸出热源竖壁、另一侧为绝热竖壁的二维垂直换热通道,研究了物性变化相比于常物性和Boussinesq假设对通道内最大温度和平均Nu数的影响。通过网格无关性验证,证实了计算程序的有效性,并修正了无量纲最大温度的公式为幂函数形式。计算结果验证了,在Gr〉7．5×10。时,变物性对非对称通道换热的必要性。     

Convective heat transfer and second law analysis of non-Newtonian fluid flows with variable thermophysical properties in circular channels

This study presents an analytical solution, for fully developed non-Newtonian fluid flows in circular channels under isoflux thermal boundary conditions based on perturbation techniques. Since the physical properties are generally a function of temperature and may not be assumed constant under certain circumstances, the change in viscosity and thermal conductivity with temperature was taken into account. Viscous dissipation term was also included in the performed analysis. In this study, first closed form expressions for velocity, temperature distributions, and Nusselt numbers corresponding to constant thermophysical properties were given in terms of governing parameters. Then, numerical calculation was performed to obtain the values of Nusselt number and global entropy generation for variable thermophysical properties. The results revealed that neglecting the property variation significantly affects heat transfer characteristics and entropy generation, in which the deviation from the constant physical property assumption may reach up to about 32.6%.     

Influence of variable property effects on natural convection flows in asymmetrically-heated vertical channels

The influence of variable property effects on the laminar air flow induced by natural convection in a vertical, asymmetrically-heated channel is investigated. A full-elliptic model that accounts for variations of viscosity and thermal conductivity with temperature and determines the density from the state equation, has been solved numerically for cases for which variable property effects are important, particularly for conditions for which flow reversals may appear. The corresponding numerical results are compared with those obtained from an alternative model in which all thermophysical properties are assumed to be constant and the Boussinesq approximation is used. It has been found that variable property effects have a strong influence, not reported in previous works, on the recirculation patterns, and may produce, for certain ranges of parameters that roughly coincide with those for which flow reversals exist, an increase in the mass flow rate induced in the channel.     

Analytical prediction of heat capacity of molten AgCl and CuCl with application to thermochemical Cu-Cl cycle for hydrogen production

To sustain our power-dependent world, there is a need for technological innovation in all aspects of science and engineering. Many times, thermophysical and material properties are not well defined for the specific application, which leads to implementing assumptions and approximations from the published data. In the thermochemical copper-chlorine (Cu-Cl) cycle for hydrogen (H₂) production, heat is recovered from cuprous chloride (CuCl) molten salt and it is then reacted with hydrochloric acid (HCl) in stoichiometric proportions to produce the anolyte for the H₂ production step of the cycle. However, the lack of precise thermophysical properties on CuCl heavily hinders the detailed investigations of heat recovery from the molten salt as it cools from 450 °C to 90 °C. In this paper a new method is developed to determine the thermophysical property of CuCl and silver chloride (AgCl) as the molten salts are changing phases to solid. This is achieved by correlating electrochemistry data with thermal data. A model that predicts the specific heat capacity during phase change process is developed based on the existing electromotive force (EMF) and thermal data from literature. Developed model shows the EMF derived specific heat capacity values of AgCl and CuCl are similar with a slight offset since they have similar EMF's at higher temperatures.