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介绍了贮热装置的主要相变材料(52#精石蜡)和主要传热元件(重力式热管),讨论了这种贮热装置总贮热量和换热能力的实验测试,探讨了贮热室相变材料的温度对贮热效率的影响。 相似文献
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发展了一种用于测量相变贮热材料及其构件贮热能力的单水浴法。这种方法使用一个其中盛有一定量水的恒温水浴,将水温从T1均匀加热到T2,利用热流片测出通过水浴各壁面的热损,用消耗的电能扣除热损后即得到加热水所消耗的电能Qw;之后将待测相变材料或其构件浸没在水中,将水浴温度调到T1,并从该温度均匀加热到T2,同时利用热流片测出通过水浴各壁面的热损,消耗的总电能扣除相应的热损后即得加热水和相变材料或其构件所消耗的电能Qw+pom;Qw+pom减去Qw即为相奕材料或其构件从温度T1升高到T2所吸收的热能,即相变材料或其构件在温度区间[T1,T2]上的贮热能力。利用该方法对一种定形相变材料的贮热能力的测试结果与DSC分析的结果相差不到2%,还利用该方法对颗粒状定形相变材料与混凝土共混成型的贮热构件的贮热能力进行了测试。 相似文献
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本文在总结作者前期相关研究工作的基础上,应用有限差分法对组合式相变材料贮能系统进行了数值模拟,重点探讨了相变温度分布对系统相变时间的影响。结果表明:①在忽略显热条件下导出的最佳线性相变温度分布与组合式相变材料的最佳相变温度分布相同;②与传统单一相变材料贮能系统相比,通过合理布置相变温度分布,组合式相变材料的贮能系统蓄能-释能速率可提高25 ̄40%。 相似文献
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脂肪酸二元体系相变贮热性能的研究 总被引:1,自引:0,他引:1
用差示扫描量热法研究了月桂酸-棕酸和月桂酸-硬脂酸两个二元体系的固-液相变,发现它们都具有良好的贮热性能,因而是一类有前途的相变贮热材料。 相似文献
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本文建立了变温相变材料(PCM)贮能的一维传导模型,分析了恒温相变、线性相变温度分布和抛物线相变温度分布对PCM相变时间的影响,在忽略显热条件下导出了相变率与相变时间的关系式并获得了最佳线性和最佳抛物线性相变温度分布。结果表明,具有特定相变温度分布的PCM在贮能系统中的应用能够显著提高蓄能、释能速度。 相似文献
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相变贮热材料的DSC研究 总被引:29,自引:7,他引:29
用DSC法研究了多元醇,层状钙钛矿等几种相变材料的热物理性能,它们都是有希望的贮热材料,实验所得数据是评价和选择这些材料的主要依据。 相似文献
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A solar adsorption cooling system which can be switched between a system with heat storage and a system without heat storage was designed. In the system with heat storage, a heat storage water tank was employed as the link between the solar collector circulation and the hot water circulation for the adsorption chillers. However, the heat storage water tank was isolated in the system without heat storage, and the hot water was directly circulated between the solar collector arrays and the adsorption chillers. It was found that the inlet and outlet temperatures for the solar collector arrays and the adsorption chillers in the system without heat storage were more fluctuant than those of the system with heat storage. Also found was that the system with heat storage operated stably because of the regulating effect by the heat storage water tank. However, under otherwise similar conditions, the cooling effect of the system without heat storage was similar to that of the system with heat storage. Compared with the system with heat storage, the system without heat storage has the advantages of higher solar collecting efficiency as well as higher electrical COP. 相似文献
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《Applied Thermal Engineering》2014,62(1):293-301
Considering the high-temperature thermal utilization of solar energy as the research background in this paper and focussing on the heat storage process, a kind of hybrid thermocline heat storage method in multi-scale structure and relevant experimental systems are designed by using the mixed molten nitrate salt as the heat storage medium and two representative porous materials, i.e. zirconium ball and silicon carbide (SiC) foam, as the heat storage fillers. The fluid flow and heat storage performance of molten salt in multi-scale structure are experimentally investigated. The results show that the theoretical heat storage efficiencies amongst the three experimental heat storage manners are less than 80% because of the existence of thermocline layers. Comparing to the single-phase molten salt heat storage, the two hybrid thermocline heat storage manners with porous fillers lead to a certain decrease in the effective heat storage capacity. The presence of porous fillers can also help to maintain the molten salt fluid as ideal gravity flow or piston flow and partially replace expensive molten salt. Therefore, it requires a combination of heat storage capacity and economical consideration for optimization design when similar spherical particles or foam ceramics are employed as the porous fillers. 相似文献
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The cascaded thermal storage technique has emerged as an important solution for efficient conversion and utilization of thermal energies. In this paper, an exergy optimization was performed for cascaded latent cold/heat storage using multi-stage heat engine model. The optimization solution for both heat storage and cold storage systems was obtained, which was used for guiding the selection of PCMs with two examples presented. Cascaded thermal storage with increased stage number can not only extend temperature band for multi-grade thermal energy, but also reduce the exergy of the outlet HTF. It was found that heat transfer enhancement (improving NTU) is very necessary for a cascaded thermal storage system. The COP of cold energy may be greater than 1, which is also higher than that of heat for the same temperature difference in a cascaded thermal storage system. The increased environment temperature improves the COP of the cascaded cold storage (from 0.54 to 0.68) but reduces that of the cascaded heat storage (from 0.42 to 0.366). In the practical design of the cascaded thermal storage system, the stage number should be determined by balancing economics and system complexity. 相似文献
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为改善潜热填充床的储/释热性能,提出了一种优化的双向变粒径球形储热单元填充结构,并基于实验室搭建的中高温相变储热实验系统,模拟分析了该结构相较于传统结构对填充床储/释热效率和时间的影响。结果表明,在保证相同储热量下,双向变粒径结构能够有效的提升储/释热效率,延长有效热流输出的时间。其中20:30:20(体积比1:1:1)的双向变粒径结构输出有效热流的时间为6685 s,放热功率为846.1 W,相对于其他的填充结构,综合热性能最好。该研究能够为进一步实现储热系统能量的高效稳定与梯度利用做铺垫。 相似文献
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S. C. Kaushik 《国际能源研究杂志》1982,6(3):253-269
This paper presents a brief review of the available latent heat storage systems for solar energy utilization. A new concept of latent heat storage of solar energy via the refrigerant-absorbent mass storage in absorption cycle heat pump systems used for solar space heating/cooling has been proposed and assessed thermodynamically. A computer modelling and numerical simulation study shows that the concept of refrigerant storage is fundamentally sound, technically feasible and yields the following advantages over other storage methods: (i) the storage capacity per unit volume is high as the latent heat of vaporization of the refrigerant is high; (ii) the heat loss from the storage to the surroundings is minimum as the storage temperature is near the ambient; (iii) prolonged energy storage is possible with no degradation in system performance and hence suitable for combined solar heating and airconditioning. The effects of operating parameters on the energy storage concentration and storage efficiency have been studied in detail. 相似文献
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This study makes an evaluation of the performances of heat storage systems destined for power plants with a discontinuous power source such as nuclear fusion. Two classes of heat storage systems are investigated: heat storage systems based on first sensible heat storage and second latent heat storage. Both classes of heat storage systems are evaluated both from a thermodynamic point of view, inquiring whether the irreversibility of the system stays limited or not, and from an economic point of view, examining whether the system makes proper use of the heat storage capacity present. It is shown that an unambiguous conclusion that one is superior to the other is not possible and that the operating conditions and the configuration of the phase‐changing materials play an important role. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献