共查询到18条相似文献,搜索用时 271 毫秒
1.
熔融盐由于具有工作温度高、蒸气压力低、热稳定性良好等优势,在集中式太阳能热发电系统中可作为传热和蓄热工质。工作温度对熔盐的传热蓄热性能具有显著影响。本文利用分子动力学模拟方法研究了温度对二元混合碳酸盐(K2CO3:Li2CO3=38.0:62.0,摩尔分数)热导率、黏度、比热容及热扩散系数的影响。结果表明,随着温度升高,熔盐的热导率和黏度均降低,比热容和热扩散系数均增加。进一步分析径向分布函数发现,温度升高导致离子间距变小,熔盐结构变得更为紧凑,使得热导率和黏度均下降。温度越高,离子间碰撞越剧烈,因而能传输更多的热量导致热扩散系数增大。本文对高温熔盐热物性的研究可为光热发电蓄热技术发展提供指导。 相似文献
2.
3.
为了满足规模化太阳能热发电高温传热蓄热和工业余热回收利用的要求,分析并设计了NaCl-CaCl_2-MgCl_2三元熔盐体系作为传热蓄热介质。在已有的二元相图的基础上通过共形离子溶液(conformal ionic solution,CIS)模型模拟计算获得计算相图,根据计算相图所预测的低共熔点配比制样,采用热重差热联用分析仪(TG-DSC)对样品的熔点、相变潜热进行了表征,采用高温静态法对熔盐的稳定性进行了初步分析。结果表明:计算相图预测的低共熔点(424℃)与测试结果(428.5℃)基本一致,该熔盐相变潜热高达到191.7 J/g,熔盐在低于600℃下较稳定,适合作为高温潜热蓄热材料。研究为氯化物熔盐相图和热物性提供了宝贵的数据。 相似文献
4.
5.
熔融盐以其优良的性能在太阳能热发电站中常被用作储热和蓄热介质,然而由于蓄热的熔融盐工作温度高达500?600℃,这就使得熔融盐对蓄热系统材料的腐蚀成为一个关键问题。本文以美国新月沙丘塔式熔盐太阳能热电站为原型,针对其运行情况,自主设计并搭建旋转式高温NaNO3/KNO3二元熔盐腐蚀特性模拟实验系统,探究了304不锈钢在特定温度、不同流速、不同时间协同作用下的腐蚀动力学特性,并利用SEM、EDX、XRD等分析测试技术探索材料表面的微观腐蚀形貌和腐蚀产物形态及元素组成,揭示了304不锈钢在高温流动熔融盐中的腐蚀行为规律和腐蚀机理。 相似文献
6.
7.
8.
9.
10.
11.
12.
在回顾和总结强脉冲电子束表面改性实验的基础上, 利用有限元数值计算方法对强脉冲电子束辐照铝和304不锈钢产生的温度场进行模拟, 给出了靶的近表面区域流体状态存在的特征尺度和特征时间, 并对不同材料特性下熔坑的产生原因进行了讨论. 采用两相流模型, 通过水平集方法和有限元方法结合的计算流体力学模拟了熔坑和表面突起形貌在表面处于熔融状态下的运动特征, 通过和实验数据相对比, 验证了对于高黏度, 高表面张力的高熔点金属, 表面处于流体状态下的张力驱动效应是熔坑等表面形貌演化的重要原因. 相似文献
13.
有机朗肯循环发电技术是基于有机朗肯循环(Organic Rankine Cycle, ORC),利用低沸点有机工质,将低品位的余热资源转换为高品位的电能的先进技术,能够有效提高能源的利用率,减少能源损失。针对工业过程中大量中低温余热受到各种限制难以回收利用难题,全面综述了有机工质朗肯循环低温余热发电技术现状和进展,具体包括循环工质、关键设备、系统优化以及产业应用等。分析表明,该技术可广泛用于地热能、生物质能、太阳热能等领域的低品位热能开发与利用,其产业化推广将有效提高普遍存在的低温余热利用效率。 相似文献
14.
操作参数对熔融盐高温斜温层蓄热性能的影响 总被引:1,自引:0,他引:1
首先提出了一种新型熔融盐高温斜温层耦合蓄热单罐系统,然后基于多孔介质局部热平衡理论,建立了熔融盐高温斜温层蓄热的局部热平衡数值模拟模型,研究了熔融盐进口流速、进口温度及工作温差等操作参数对斜温层蓄热单罐热性能的影响,并在熔融盐传热-蓄热实验平台上进行了试验研究。发现:当进口速度为0 001 m/s级及降低工作温差等有利于降低斜温层厚度,模拟得到的蓄热单罐轴向温度分布变化与实验结果趋于一致。因此,合理选取这些参数对蓄热单罐的正常运行是非常必要的,结果可以用于指导蓄热单罐的设计。 相似文献
15.
On account of excellent thermal physical properties, molten nitrates/nitrites salt has been widely employed in heat transfer and thermal storage industry, especially in concentrated solar power system. The thermal stability study of molten nitrate/nitrite salt is of great importance for this system, and the decomposition mechanism is the most complicated part of it. The oxide species O22- and O2- were considered as intermediates in molten KNO3-NaNO3 while hard to been detected in high temperature molten salt due to their trace concentration and low stability. In this work, the homemade in situ high temperature UVVis instrument and a commercial electron paramagnetic resonance were utilized to supply evidence for the formation of superoxide during a slow decomposition process of heat transfer salt (HTS, 53 wt% KNO3/40 wt% NaNO2/7 wt% NaNO3). It is found that the superoxide is more easily generated from molten NaNO2 compared to NaNO3, and it has an absorption band at 420-440 nm in HTS which red shifts as temperature increases. The band is assigned to charge-transfer transition in NaO2 or KO2, responsible for the yellow color of the molten nitrate/nitrite salt. Furthermore, the UV absorption bands of molten NaNO2 and NaNO3 are also obtained and compared with that of HTS. 相似文献
16.
María Jos Montes Jos Ignacio Linares Rubn Barbero Beatriz Yolanda Moratilla 《Entropy (Basel, Switzerland)》2020,22(8)
One of the ways to make cost-competitive electricity, from concentrated solar thermal energy, is increasing the thermoelectric conversion efficiency. To achieve this objective, the most promising scheme is a molten salt central receiver, coupled to a supercritical carbon dioxide cycle. A key element to be developed in this scheme is the molten salt-to-CO2 heat exchanger. This paper presents a heat exchanger design that avoids the molten salt plugging and the mechanical stress due to the high pressure of the CO2, while improving the heat transfer of the supercritical phase, due to its compactness with a high heat transfer area. This design is based on a honeycomb-like configuration, in which a thermal unit consists of a circular channel for the molten salt surrounded by six smaller trapezoidal ducts for the CO2. Further, an optimization based on the exergy destruction minimization has been accomplished, obtained the best working conditions of this heat exchanger: a temperature approach of 50 °C between both streams and a CO2 pressure drop of 2.7 bar. 相似文献
17.
18.
A.E. Gheribi D. Corradini L. Dewan P. Chartrand C. Simon P.A. Madden 《Molecular physics》2014,112(9-10):1305-1312
Molten fluorides are known to show favourable thermophysical properties which make them good candidate coolants for nuclear fission reactors. Here we investigate the special case of mixtures of lithium fluoride and thorium fluoride, which act both as coolant and as fuel in the molten salt fast reactor concept. By using ab initio parameterised polarisable force fields, we show that it is possible to calculate the whole set of properties (density, thermal expansion, heat capacity, viscosity and thermal conductivity) which are necessary for assessing the heat transfer performance of the melt over the whole range of compositions and temperatures. We then deduce from our calculations several figures of merit which are important in helping the optimisation of the design of molten salt fast reactors. 相似文献