层叠式高温相变蓄热系统传热特性的实验研究

Experimental Study on Heat Transfer Characteristics of Laminated High-Temperature Phase Change Heat Storage System

为研究层叠式高温相变蓄热系统的传热特性,采用二元熔盐Solar Salt(质量比NaNO3:KNO3=6:4)为相变材料,以空气为换热介质,记录不同风速下蓄热箱体内部的温度变化。通过层叠式高温相变蓄热系统的放热实验,分析蓄热箱体内部蓄热单元的传热特性,进而对蓄热箱体内部传热效率低的区域进行传热优化。通过在相变材料Solar Salt中添加不同质量分数的膨胀石墨,提高相变材料的导热系数,进而改善传热效率低的区域。实验表明:在蓄热箱体内部,靠近出风位置的蓄热单元A2降温到200℃所需时间分别比靠近进风位置的蓄热单元B2和C2多10.5%和37.4%。为解决靠近出风位置的A列蓄热单元传热效率低的问题,在A列蓄热单元的Solar Salt中添加膨胀石墨,可以显著改善蓄热箱体内部的传热情况,明显提高了系统的换热能力,且风速为1.53 m/s时相邻配比材料效率提升最大。

In order to study the heat transfer characteristics of the laminated high-temperature phase change heat storage system,Solar Salt(NaNO3∶KNO3=6∶4)is used as the phase change material and air as the heat transfer medium to record the temperature change inside the heat storage chamber at different wind speeds.Through the exothermic experiments of the laminated high-temperature phase change thermal storage system,the heat transfer characteristics of the thermal storage units inside the thermal storage chamber are analyzed,and the areas with low heat transfer efficiency inside the thermal storage chamber are optimized for heat transfer.By adding different mass fractions of expanded graphite to the phase change material Solar Salt,the thermal conductivity of the phase change material is improved,and the areas with low heat transfer efficiency are improved.The experiment results show that inside the thermal storage chamber,the time required for the thermal storage unit A2,which is closer to the outlet air position,to cool down to 200℃is 10.5%and 37.4%more than the thermal storage units B2 and C2,which are close to the inlet air position,respectively.In order to solve the problem of low heat transfer efficiency of the heat storage unit in column A near the air outlet position,the addition of expanded graphite in Solar Salt of the heat storage unit in column A can significantly improve the heat transfer inside the heat storage box and significantly increase the heat transfer capacity of the system,and the efficiency of adjacent proportional materials is increased the most when the wind speed is 1.53 m/s.