Melting and Solidification Heat Transfer Characteristics of a Phase-Change Material in a Latent Heat Storage Vessel: Effects of a Perforated Partition Plate and Metal Fiber

Today, latent heat storage technology has advanced to allow reuse of waste heat in the middle-temperature range. This paper describes an approach to develop a latent heat storage system using middle-temperature waste heat (~100oC - 200oC) from factories. Direct contact melting and solidification behavior between a heat-transfer fluid (oil) and a latent heat storage material mixture were observed. The mixture consisted of mannitol and erythritol (Cm = 70 mass %, Ce = 30 mass %) as a phase-change material (PCM). The weight of the PCM was 3.0 kg and the flow rate of the oil, foil, was 1.0, 1.5, or 2.0 kg/min. To decrease the solidified height of the PCM mixture during the solidification process, a perforated partition plate was installed in the PCM region in the heat storage vessel. PCM coated oil droplets were broken by the perforated partition plate, preventing the solidified height of the PCM from increasing. The solidification and melting processes were repeated using metal fiber. It was found that installing the metal fiber was more effective than installing the perforated partition plate to prevent the flow out problem of the PCM.

直驱式光伏电-热复合相变蓄热板热性能及其建筑供暖可行性探讨

太阳能光伏技术的发展为我国北方地区建筑冬季可再生能源供暖提供了可能,然而光伏组件系统不稳定的低压直流电力特性,与建筑电力能源系统稳定的交流电力特性不具匹配性,给光伏电力高效应用带来挑战。本文基于课题组提出的直驱式光伏电-热复合相变蓄热墙体设计理念,搭建了电-热复合相变蓄热板实验台,结合实验与理论分析方法,研究了墙板光伏电-热特性、相变蓄热及其传热特性;进一步搭建了1:8缩尺阳光房实验台,研究并把握该墙板应用于建筑供暖的可行性。实验结果表明,光伏组件系统日输入电量1.8 kW·h/d、室外环境温度18℃条件下,电-热复合相变热板蓄放热效率为93.3%、有效放热时间可达12 h;缩尺模型实验房间较对照房间空气温度平均提高3.6℃,夜间北壁体内表面温度提高7.2℃,北墙体夜间向室内供热量的72%由光伏电贡献。研究结果可为光伏电-热相变蓄热供暖技术在建筑领域的广泛应用提供重要参考。

石墨/铝合金复合导热板强化石蜡相变蓄热研究

本文对“三明治”结构的石墨/铝合金复合导热板强化石蜡的相变蓄热特性进行了数值研究,探究泡沫金属、平板翅片以及复合导热板三种传热结构对石蜡相变蓄热过程的影响。然后本文在石墨/铝合金复合导热板的结构基础上添加了二级翅片来强化传热。研究表明:石墨/铝合金复合导热板强化石蜡相变蓄热的性能明显优于其他传热结构,呈现出自导热板向垂直于板两侧方向递减的温度分布,使得腔体内融化最为均匀,芯片温升最小。添加二级肋片后热源温升减小了15.87%,有效工作时间延长64.68%。