共查询到15条相似文献,搜索用时 140 毫秒
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本文面向电蓄热采暖应用设计了一种新型内嵌式热管,通过可视化和传热实验研究了充液率在5%至70%之间变化时热管内部的流型演化规律和传热特性。根据流型演化过程可以将充液率分为小、中、大三个类别。小充液率时,热管内部出现间歇剧烈沸腾过程;中等充液率时,热管内部出现持续沸腾现象,冷凝段受到搅混流的周期性冲刷;大充液率时,气液混合工质在绝热段往复振荡,冷凝段始终存在液态工质。对于充液高度小于加热段高度和充液高度大于加热段高度两种情况,随着充液率的增大,热阻均先降低后升高,但充液高度大于加热段高度时的热阻普遍大于充液高度小于加热段高度时的热阻。10%充液率时热阻最小,80 W加热功率时约为0.017℃/W,此时蒸发段为持续薄液膜蒸发传热,冷凝段为周期性扰动冷凝和强制对流耦合传热。 相似文献
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以R600A为工质的分离式热管的实验研究 总被引:1,自引:0,他引:1
对分离式热管的整体热量传递特性进行了实验研究。以蛇形翅片管作为冷凝段和蒸发段进行热管实验,探讨了蒸发器进风面风温及分离式热管蒸发器与冷凝器之间高度差、工质充注量对分离式热管的影响。实验表明,随着蒸发器进风温度的升高,蒸发器与冷凝器换热系数都是呈现先增大后减小的趋势。在冷凝端进风温度恒定为16.55℃、蒸发端进风温度低于60℃时,以R600A为工质的分离式热管的传热量曲线近似于二次曲线,蒸发端进风温度高于60℃时,其传热量曲线近似于一条直线。加大充液率及增加蒸发器与冷凝器的高度差,分离式热管的传热能力均会得到提高。 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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An experimental energy storage system has been designed using a new type flat micro heat pipe heat exchanger that incorporates a moderate-temperature phase change material paraffin with a melting point of 58°C. The basic structure, working principles, and design concept are discussed. The heat transfer process during the charging and discharging of the heat exchanger under various operating conditions has been experimentally investigated. Results show that the performance of the new type flat micro heat pipe was steady and efficient during charging and discharging. The average thermal storage power and absorption efficiency have been determined to be approximately 537 W and 92.5%, respectively. 相似文献
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《Heat Recovery Systems and CHP》1990,10(5-6):509-517
The present paper is concerned with studying the effects of storage medium properties on the thermal behaviour of packed beds during charging. A transient one-dimensional two-phase model is used to describe the temperature fields in the air and solid media constituting the bed. The numerical solution of the resulting two-coupled partial differential equations is obtained, and the variation of thermal energy stored with time is computed. Solutions are obtained for a wide range of storage media (the solid phase) properties, namely density, thermal conductivity and specific heat. The results show that increasing either the density or specific heat increases the rate and capacity of energy storage, and decreases the rate of temperature rise throughout the storage medium. On the other hand, increasing the thermal conductivity is found to markedly increase the rate of temperature rise and energy stored inside the bed up to a certain time during charging, beyond which this trend completely reverses. In addition, the thermal storage properties of aluminum, steel and rock-packed beds are computed and compared. 相似文献
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分离式热管换热器传热特性的实验研究 总被引:1,自引:0,他引:1
本文在自行设计分离式热管实验装置的基础上,对其传热特性进行了实验研究。其工作温度为170~250℃,热流密度为25~50 kW/m~2。蒸发段和冷凝段构成相同,均是由7根直径30 mm的无缝钢管短管束组成,管长为160 mm,带有紧套的钢帛环形肋片结构尺寸为:外径45 mm、厚1 mm、片间距4 mm。实验结果表明,在本实验条件下,分离式热管的最佳充液率按管束总容量计为18%~38%。根据实验结果拟合了最佳充液率(24%)下蒸发段内部平均沸腾换热系数和冷凝段内部凝结换热努塞尔数综合关系式。 相似文献