移动蓄热系统蓄热器的加肋强化换热试验研究

Experimental Study on Heat Transfer Enhancement of Heat Exchanger in Indirect Mobilized Thermal Energy Storage System with Fins

为解决工业废热与分布用户的地域差异,设计以赤藻糖醇为相变材料的移动蓄热系统,所用双直肋式翅片管不仅增大换热面积,并且在蓄热熔化和放热凝固过程中加大自然对流扰动区域,起到了强化换热作用。通过试验研究其充放热特点和效率,并分析传热介质流量对充放热过程的影响。试验结果表明,蓄热相变过程,材料温度变化不大;释热过程,蓄热器具有较快的冷却速度,使得赤藻糖醇凝固过程表现出过冷现象;传热介质流量对充放热过程影响不明显。在所设定试验工况下充热需210 min,放热需120 min,在用户侧能将0.115 m3的水从10℃加热到55℃,热回收效率达84%。直肋翅片管相变蓄热装置具有良好的蓄、放热性能,为移动蓄热车在工业废热利用等领域的工程应用提供了可能。

To recover waste heat for the distributed users, an indirect mobilized thermal energy storage（M-TES） system is designed incorporating a medium temperature phase change material（PCM） erythritol. Because the low thermal conductivity of the PCM, the copper tube that with double straight fins is chosen to help enhance the heat exchange. The thermal characteristics in the system are analyzed using temperature time curves. The investigation shows that the temperature of the PCM rises rapidly in the solid sensible heat stage in the heat storage process, but there is almost no temperature change in the latent heat stage. The natural convection can make the PCM melt faster. The melt process of the PCM takes 210 rain. The temperature of the heat source has influence on the charging time and the temperature gradient of the PCM. In the heat release process, the PCM shows sub-cooling phenomenon. The investigationalso shows that 16 790 kJ of heat is released in the initial 120 rain of discharging process that accounts for 84 % of heat capacity of the M-TES container, which can heats 0.115 m3 of water om 10 ℃ up to 55 ℃. The system shows a good performance in energy storage process： It makes the mobile energy storage car can be truly used for recover industrial waste heat.