共查询到19条相似文献,搜索用时 203 毫秒
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相变材料微胶囊流体相变过程对储热蓄热影响 总被引:1,自引:0,他引:1
用石蜡混合物(以C_(19)H_(40)为主体,相变温度:25~38℃,比热容极大值出现在31.5℃左右)作芯材,树脂材料作囊壁,与水混合制备成微纳米胶囊流体,将其填充在矩形密闭容器内,在下表面加热,其余各表面绝热条件下,对相变材料相变化过程的储热蓄热特性进行分析。结果表明,相变材料相变化过程提前了自然对流的启动时间,加强了换热强度;在蓄热温度超过35℃之前,相变化的促进作用随温度增加而逐渐增强,超过35℃以后,相变化的促进作用开始减弱. 相似文献
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印刷电路板换热器是超高温气冷堆等高温能量利用与回收领域中极具潜力的备选强化传热技术之一,本文通过数值模拟方法对典型Z字形印刷电路板(PCHE)传热通道的传热和阻力特性开展了相关研究。计算结果表明:层流模型可以较好地获得Z字形PCHE通道的阻力和传热性能,Z字形PCHE通道的阻力系数大于半圆管直通道的阻力系数;当热侧和冷侧通道流体入口温度均不发生改变时,增加两侧流体的质量流量,通道内的阻力系数随之减小,传热效率也稍微减小;当两侧流量及冷侧入口温度均不发生改变时,提高热侧通道入口温度,通道内阻力系数成线性增大,传热效率也随之提高。 相似文献
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热管式相变蓄热换热器储/放能过程中传热特性的实验研究 总被引:1,自引:0,他引:1
将热管作为换热元件应用于相变蓄热系统中,研制了一套热管式相变蓄热换热器。采用石蜡作为蓄热材料,对其储、放能过程即内部石蜡的融化与凝固过程进行了实验研究。测定了储、放能过程中不同时刻换热器内石蜡的温度分布; 改变供、取热流体参数,分析了供/取热流体的入口温度与流量对换热器储/放能过程的影响;分析了储、放能过程中能量随时间的变化情况。结果表明,热管在本换热器内极好地发挥了换热元件的作用,换热器运行状况良好,各项功能均能较好地实现。 相似文献
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M. K. Rathod 《实验传热》2013,26(1):40-55
Thermal performance of a latent heat storage unit is evaluated experimentally. The latent heat thermal energy storage system analyzed in this work is a shell-and-tube type of heat exchanger using paraffin wax (melting point between 58°C and 60°C) as the phase change material. The temperature distribution in the phase change material is measured with time. The influence of mass flow rate and inlet temperature of the heat transfer fluid on heat fraction is examined for both the melting and solidification processes. The mass flow rate of heat transfer fluid (water) is varied in the range of 0.0167 kg/s to 0.0833 kg/s (1 kg/min to 5 kg/min), and the fluid inlet temperature is varied between 75°C and 85°C. The experimental results indicate that the total melting time of the phase change material increases as the mass flow rate and inlet temperature of heat transfer fluid decrease. The fluid inlet temperature influences the heat fraction considerably as compared to the mass flow rate of heat transfer fluid during the melting process of the phase change material. 相似文献
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In this study, beeswax as a new energy storage material and its composite with expanded graphite were prepared and characterized for their surface and thermal properties. Surface characterization showed no chemical interaction between beeswax and expanded graphite. The thermal conductivity of the composite was improved with 117% enhancement. The thermal performance of beeswax and its composite as a heat storage material was studied in a rectangular shell-and-tube thermal storage unit. The melting point of the composite remained almost same as that of beeswax; however, the melting time was reduced considerably, from 540 to 360 min with inlet water at 80°C and a 2-lpm flow rate. 相似文献
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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
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In this paper thermal performance of graphite-based sensible heat storage system with embedded helical coil in rectangular shell was studied. Plain water at four flow rates (0.25 LPM–1.0 LPM) and four inlet temperatures (60°C–90°C) was passed through the graphite bed and charging time was measured. Expanded graphite/water suspension and Al2O3/water nanofluid were also used to study charging behavior of graphite. Results showed that charging time of packed bed was reduced with increase in flow rate and inlet temperature of heat transfer fluid. Charging time using expanded graphite/water solution and nanofluid was 14.2% and 21.2% lesser than water.Abbreviations: hi: internal heat transfer coefficient (W m?2 K?1); HTF: Heat transfer fluid; ho: External heat transfer coefficient (W m?2 K?1); LPM: liter per minute; k: thermal conductivity (W m?1 K?1); TSU: Thermal storage unit 相似文献
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在5 GPa压力下对铝青铜进行750℃、保温15 min的高压热处理,对高压热处理前后铝青铜的电导率以及25~600℃温度范围内的热扩散系数、热容和热导率进行测试,结合显微组织的观察结果,探讨了高压热处理对铝青铜热物理性能的影响。研究表明:高压热处理能增大铝青铜的热扩散系数,减小热容;对热导率而言,温度低于400℃时高压热处理能增大铝青铜的热导率,而温度高于400℃时高压热处理能减小铝青铜的热导率。分析认为,产生变化的主要原因是高压热处理使铝青铜的微观组织发生了变化。 相似文献
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