三元混合碳酸熔盐热物性实验研究

为满足超临界二氧化碳太阳能光热发电系统高温传热储热的要求,对3种不同比例的高温混合碳酸熔盐的热物性进行研究.实验结果表明,1号、2号、3号混合碳酸熔盐的熔点分别为388.7、337.9、391.3℃;初晶点分别为454.9、639.7、535.4℃;1号、3号混合碳酸熔盐的分解温度分别为916.2、920.4℃.通过分...     

熔盐物性对熔盐泵内部流动及圆盘损失特性影响

以太阳能热发电高温熔盐泵为研究对象,对不同介质条件下熔盐泵内部流动特性和圆盘损失进行分析.对比清水试验和数值计算结果,验证数值计算的可行性,通过对清水、300℃熔盐、565℃熔盐条件下熔盐泵流场进行计算,获得首级泵段内清水和不同温度下熔盐在熔盐泵内的速度、压力分布,分析了介质物性对泄漏量、圆盘损失以及盖板剪切应力分布产...     

KNO3-NaNO2-KNO2三元系相图筛选及物性测试

为研发出与太阳能热发电技术相匹配的新型传/蓄热熔盐材料,选取KNO₃、NaNO₂和KNO₂作为研究对象,基于亚正规溶液模型对KNO₃-NaNO₂-KNO₂三元系相图展开热力学理论计算,同时采用相图软件FactSage 8.2对该体系相图进行模拟,结合试验确定体系共晶点,并对优选熔盐的储热能力进行研究。结果表明,采用亚正规溶液模型计算的三元熔盐的共晶点数据具有较高的准确性。优选出的混合熔盐的组成为42.0% KNO₃-48.5% NaNO₂-9.5% KNO₂（百分数为物质的量分数）,实测熔点为139.8 ℃,熔化终止点为146.3 ℃,熔化热为71.1 J/g,分解温度为652.0 ℃,平均液态比热容约为1.48 J/（g∙K）。     

新型低熔点混合熔盐储热材料的开发

硝酸盐作为储热介质具有使用温度高、传热性能好、比热容大等优势,开发新型多元低熔点熔盐储热材料可以解决传统二元盐存在的储能效率低和管道冻堵等问题.本文基于相图热力学计算CALPHAD方法,利用PANDAT软件开展NaNO3-NaNO2-KNO2三元体系相图热力学计算并获得该三元体系的共晶点成分配比,经测试实验结果和理论结...     

Li2CO3-Na2CO3-K2CO3相图的理论预测

熔盐是一种重要的聚光太阳能系统传热流体,多元熔盐混合是满足实际需求的有效方法,而熔盐混合物的相图是其筛选的主要因素之一.该文基于热力学原理及吉布斯自由能对Li2CO3-Na2CO3-K2CO3的相图进行预测与计算,结果显示:该熔盐混合物的共晶点为421.2℃,Li2CO3、Na2CO3和K2CO3的质量分数分别为25....     

NaNO_3-KNO_3-NaNO_2三元混合相变熔盐结构与物性的分子动力学模拟CSCD

相变熔盐目前是太阳能热发电的重要传蓄热介质,其结构和性质之间的定量关系是相变熔盐研究的热点。本文采用分子动力学方法,利用Buckingham势函数,对NaNO_3-KNO_3-NaNO_2三元混合熔盐的结构和性质进行了研究。计算了混合熔盐在不同温度下的径向分布函数、配位数、角分布函数等结构信息,以及密度、剪切黏度、热导率、比热容等性质。结果表明,计算得到的各项性质与文献值吻合较好,验证了势函数和计算方法的可靠性,为计算机模拟指导熔盐配方、熔盐构效关系定量研究奠定了基础。     

NaCl-MgCl2-CaCl2相图计算方法研究

为满足规模化太阳能热发电中对传热蓄热的要求,针对储能材料开展探究。以熔融盐热物性及经济性作为筛选条件,选定来源广泛、价格低廉、工作温度范围宽、黏度低、相变潜热大的NaCl、MgCl₂和CaCl₂三元熔盐体系开展深入研究。应用修正的准化学溶液模型,在子二元系基础上推导计算三元混合熔盐NaCl-MgCl₂-CaCl₂相图。结果表明,该熔盐混合物共晶点温度为412.45 ℃,NaCl、MgCl₂和CaCl₂的摩尔分数分别为50.99%、22.78%和26.23%,与已有文献数据相比,误差在3%以内,验证了方法的准确性,为构建熔盐氯化物相图数据库奠定了部分基础。     

低熔点多元混合熔盐的制备及其性能研究

为了获得聚光型太阳能热发电用的更低熔点熔融盐储热传热材料,采用材料掺杂改性方法,在Li NO3-KNO3-Ca(NO3)2三元低熔点共晶混合盐中加入Na Cl,制备了Li NO3-KNO3-Ca(NO3)2-Na Cl新混合熔盐。对新混合熔盐分别进行了DSC熔点测定、TG动态热稳定测定、48 h静态热稳定测试和熔盐液态密度测定。DSC实验结果表明,新混合熔盐的熔点为109.3℃,比原三元混合熔盐的熔点(117.2℃)降低了7.9℃,对应的相变潜热为48.6 J/g;TG动态热稳定和静态热稳定实验表明,新混合熔盐的热稳定温度为500℃,比原三元混合熔盐的热稳定温度(450℃)高50℃;液态密度实验发现,该混合熔盐在180~500℃时的液态密度为1.7~1.9g/cm3。     

熔融盐热物性的测量方法

一前言太阳能热发电作为一种可再生能源发电技术,与传统发电方式的区别在于传统发电方式能量来源于燃烧的煤、石油或者其他化学能源产生的能量,而太阳能热发电是利用聚光装置将能量热流密度低的太阳能转化为能量密度高的能量,利用传热介质吸热,并在换热器内与水进行换热,最后进入传统     

镍基高温合金热物性参数计算及测量

利用热力学软件Thermo-Calc描述了某种镍基高温合金在不同温度下共存相的平衡摩尔分数以及体积分数,计算了密度、比热、线膨胀系数等合金热物性参数,并与实验测量值进行比较,计算值与实验测量值符合的很好。     

A study of the operating characteristics of an experimental absorption cooler using ternary systems

An alternative to the use of the traditional lithium-bromide/water system for absorption cooling is discussed. An experimental study is presented on the use of salt mixtures of lithium-bromide/zinc-bromide and lithium-bromide/lithium-iodide as absorbents for water. It is shown that the higher solubilities of the ternary systems allows operation at higher absorber and generator temperatures without the risk of crystallization and with low enough evaporator temperatures for practical cooling applications.     

Hydrogen storage in binary and ternary Mg-based alloys: A comprehensive experimental study

This study focused on hydrogen sorption properties of 1.5 μm thick Mg-based films with Al, Fe and Ti as alloying elements. The binary alloys are used to establish as baseline case for the ternary Mg–Al–Ti, Mg–Fe–Ti and Mg–Al–Fe compositions. We show that the ternary alloys in particular display remarkable sorption behavior: at 200 °C the films are capable of absorbing 4–6 wt% hydrogen in seconds, and desorbing in minutes. Furthermore, this sorption behavior is stable over cycling for the Mg–Al–Ti and Mg–Fe–Ti alloys. Even after 100 absorption/desorption cycles, no degradation in capacity or kinetics is observed. For Mg–Al–Fe, the properties are clearly worse compared to the other ternary combinations. These differences are explained by considering the properties of all the different phases present during cycling in terms of their hydrogen affinity and catalytic activity. Based on these considerations, some general design principles for Mg-based hydrogen storage alloys are suggested.     

Energy consumption patterns in the Canadian and world economies The use of a ternary primary energy diagram

A new method is presented for showing the distribution of primary energy forms by use of the ternary diagram. An arbitrary division of energy sources into oil, other exhaustibles, and inexhaustibles (renewables sources and uranium) is made, but other choices may be made if desired. The ternary primary energy diagram is an effective means of showing important changes and characteristics of the energy system, both in terms of the historical record and to illustrate the routes available to reduce, for instance, petroleum dependence. Trends in the pattern of Canada's energy consumption are identified, and with the help of the ternary diagram, some options for energy policy are evaluated.     

The application and experimental validation of a heat and mass transfer analogy model for the prediction of mass transfer in solar distillation systems

In the present investigation efforts have been made for the validation of a new theoretical model, allowing the prediction of mass transport in the barometric enclosure of solar distillation systems. It appears that this model which is based on the Chilton–Colburn analogy being applicable for a broad range of Prandtl and Schmidt dimensionless numbers, can potentially be employed at a wide range of operating conditions and may turn out to become an accurate, more universal alternative to the widely known Dunkle's theoretical model. The comparative validation is carried out employing a set of field experimental measurements which were derived in a passive solar still under favorable climatic conditions during mid summer, aiming validation at higher operating temperature conditions. It is derived that the model is impressively accurate for predictions of the derived measurements in a wide range of average operating temperatures higher than about 70 °C and up to about 0.2 gr/m² s yields.     

The steady-state solidification scenario of ternary systems: Exact analytical solution of nonlinear model

A mathematical model describing the steady-state solidification of ternary systems with mushy layers (primary and cotectic) is formulated: solidification along a liquidus surface is characterized by a primary mushy layer, and solidification along a cotectic line is characterized by a secondary (cotectic) mushy layer. Exact analytical solutions of the model under consideration are found in a parametric form (thicknesses of mushy layers, growth rate of their boundaries, temperature and composition fields, solid fractions are determined in an explicit form). The velocity of solidification is completely determined by temperature gradients in the solid and liquid phases. This velocity coincides with similar expressions describing binary melt solidification with a planar front or a mushy layer. It is shown that the liquid composition of the main component decreases in the cotectic and primary layers, whereas the second (cotectic) composition increases in the cotectic layer, attains a maximum point and decreases in the primary layer.     

Thermodynamic methodology of energy-flow framework diagram for technical energy systems

This paper presents a novel thermodynamic analysis tool, the energy-flow framework diagram (EFD), and proposes a new method called the EFD graphic analysis method. It is a visual method of energy analysis and integration and is fairly convenient to analyze variety of complicated information, with the aim at bring forward a creative energy-saving system. It is proved that the new method is effective and useful through an application study on a 560 kt/a methanol synthesis process by means of the EFD and the revelatory criteria.     

Numerical prediction of heat pump dynamic behaviour using ternary non-azeotropic refrigerant mixtures

A lumped parameter model presented in this paper, to predict the dynamic behaviour, is an extension of binary modelling of heat pumps with non-azeotropic refrigerant mixtures. The mathematical formulation of this model is based on mass, momentum, and energy balances. Several constitutive relationships are adopted in this model to describe the different phenomena encountered during heat pump operation with special emphasis on newly developed correlations to predict heat and mass transfer. In addition, the proposed model includes the consequent effect of different refrigerant flow regimes and slip between the two phases. Extensive simulations showed that the present model predicts fairly the heat pump dynamic response using ternary non-azeotropic refrigerant mixtures, and compress well with experimental data under various geometries and conditions.     

Multi‐fault detection and diagnosis of HVAC systems: an experimental study

The objective of this study is to detect faults due to multiple element failures in HVAC systems occurring concurrently. To classify and detect single as well as multiple faults, measurements were made of supply air temperature, OA‐damper position, supply fan pressure, indoor temperature and airflow rate in a variable air volume heating ventilating and air conditioning test facility. Experimental results show that three types of patterns emerge in the analysis of multi‐fault problems. To solve the multi‐fault problem, a new strategy based on pattern classification and the use of residual ratios is presented. It is shown that the residual ratio can be used to diagnose and accurately identify and detect multiple‐faults occurring in HVAC systems. Copyright © 2005 John Wiley & Sons, Ltd.     

An experimental study of two-phase closed thermosyphons for compact solar domestic hot-water systems

This paper focuses on the experimental analysis of the thermal behavior of two-phase closed thermosyphons with an unusual geometry characterized by a semicircular condenser and a straight evaporator. All the tests were done in an experimental indoor setup that uses electrical skin heaters to simulate the solar radiation. Different evaporator length, fill ratio of working fluid, cooling temperature and slope of the evaporator were tested for different heat fluxes, and the effects of these parameters on the overall thermal resistance were verified. An analysis of the transient results and the steady state performance was conducted in order to provide information for the design of a compact solar domestic hot-water system.     

Determination of phase diagrams of binary and ternary organic semiconductor blends for organic photovoltaic devices

Ternary blends were recently suggested as a sound approach to increase the short circuit current density of organic solar cells by sensitizing the bulk heterojunction (BHJ) with a further absorber, i.e., a low band gap polymer. Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b´]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT) is a suitable candidate as low band gap polymer for ternary blends with poly(3-hexylthiophene) (P3HT) and [6,6]-pheny-C₆₁-butyric acid methyl ester ([60]PCBM) due to its ideal energy level and charge carrier properties. Phase diagrams are common in polymer science to visualize the mixing behavior of multicomponent systems as a function of temperature. In this study, we have used differential scanning calorimetry (DSC) to extract phase diagrams for binary and ternary organic semiconductor blends, and built the corresponding solar cells to analyze correlations between the thermal and the electrical properties of such semiconductor blends.