石蜡基复合相变储热材料的导热性能

Paraffin based composite phase change materials for thermal energy storage: Thermal conductivity enhancement

为提高石蜡作为固-液相变储热材料的导热性能,在石蜡(PW)中掺加高导热系数的碳纳米管(CNTs),制备了碳纳米管-石蜡复合相变材料(PW-CNTs)。为进一步增强PW-CNTs的传热性能,通过内置金属网结构,利用金属网的高导热性,加快PW-CNTs作为相变材料的充放热速率。测试了PW-CNTs的熔点和相变潜热、导热系数以及置入金属网前后的充放热时间。结果显示,PW-CNTs的导热系数较石蜡得到显著提高,其中掺加10%(质量分数)CNTs的复合材料的固态、液态导热系数平均分别提高31.4%、40.2%。置入金属网结构后,PW-CNTs的充放热时间至少分别缩短了40.3%和30.2%。此外,碳纳米管在石蜡中易发生团聚沉积,针对这一特点,对PW-CNTs进行了多次热循环,研究了热循环对PW-CNTs导热系数的影响。

Paraffin wax (PW) has been widely used as a phase change material for thermal energy storage due to relatively high thermal energy storage density and other desirable properties. However, it has a low thermal conductivity (TC), leading to a long charging and discharging time. To address the issue, carbon nanotubes (CNTs) were mixed with PW to form PW-CNTs composites. As CNTs are highly thermally conductive, the use of such a material is expected to give a good level of thermal conductivity enhancement. To further enhance the heat transfer process, metal meshes were placed in the interior of the PW-CNTs composites. Experimental results show that the addition of 10% CNTs by mass leads to a thermal conductivity enhancement of 31.4% and 40.2% respectively in the solid and liquid states. The results also show that the use of metal meshes shortens the charging and discharging durations by at least 40.3% and 30.2%, respectively. Heating and cooling cycling tests have also been carried on the PW-CNTs composites and the results show a large decrease in the thermal conductivity after a few cycles due to severe aggregation of CNTs in PW-CNTs composites.