Study on Latent Heat Storage by Using Paraffin Wax-Water Emulsion

石蜡-水乳液潜热蓄热研究

• 批准号: 03650765
• 负责人: NISHIMURA Makoto
• 金额: $ 0.96万
• 依托单位: Gifu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03650765/
• 关键词: Heat Storage; Latent Heat Storage; Paraffin Wax; Emulsion; Shell-and-Tube Heat Storager

In order to use solar thermal energy and low-quality energy effectively, a means of energy storage is required. One method under study involves heat storage in the latent heat of solid-liquid phase change. It is known that paraffin waxes exhibit desirable characteristics as a phase change material for heat storage. On the other hand, paraffin waxes have some undesirable proper-ties such as: 1) low thermal conductivity, 2) relatively large volume change in phase change due to the high solubility of air in the liquid phase. Both give rise to the low heat transfer rate in charging and discharging processes. To improve this problem, it has been proposed to utilize metallic fillers, fins, and capsules. However, these techniques are not always effective.In the present study, we considered to use paraffin wax-water emulsion as a new heat storage material, which has fluidity in solid phase and relatively high thermal conductivity and fusion heat. The experiments of charging and discharging for two kinds of emulsion and water as a reference were performed by using a shell-and tube type heat storager. Time-changes of temperature of heat storage material and working fluid were measured under varied conditions of flow direction, mass flow rate, and inlet temperature of working fluid. Enthalpies charged and discharged were evaluated and compared. As a result, it was found that emulsion is a suitable and effective heat storage material to enhance heat transfer. Effects of operation condition on characteristics of charging and discharging were made clear.

为了有效利用太阳能热能和劣质能源，需要一种储能手段。正在研究的一种方法涉及固-液相变潜热中的储热。众所周知，石蜡作为相变储热材料表现出理想的特性。另一方面，石蜡具有一些不理想的性质，如：1)导热系数低；2)由于空气在液体中的高溶解度，相变体积变化较大。两者都会导致充放电过程中的换热效率较低。为了改善这一问题，已提出使用金属填充物、翅片和胶囊。然而，这些技术并不总是有效的。在本研究中，我们考虑使用石蜡-水乳液作为一种新型的储热材料，它在固相中具有较高的导热系数和熔融热，具有较高的流动性。利用管壳式蓄热器对两种乳化液和水进行了充放电实验。测量了不同流动方向、不同质量流量、不同工质入口温度条件下蓄热材料和工质温度的时间变化。对充电和放电的热焓进行了评估和比较。结果表明，乳化液是一种适合于强化换热的有效蓄热材料。明确了操作条件对充放电特性的影响。