多孔通道内CO_(2)水合物生成特性实验研究

Experimental Study on the Formation Characteristics of CO_(2) Hydrate in Porous Media

CO_(2)水合物因在常低温条件下可以达到500 kJ/kg的高潜热值被认为是未来最具有前景的蓄冷材料之一,然而其生成的平衡压力较高,形成动力学缓慢且导热系数较低而限制了其应用。本文通过引入热力学促进剂四氢呋喃(THF)发现其对降低CO_(2)水合物的生成压力有着显著作用,当THF质量分数为0.32时可以实现CO_(2)水合物在环境温度为-3℃,压力0.6MPa以下合成。通过将高导热支撑型多孔介质骨架与CO_(2)水合物进行复合,研究发现,与无泡沫铜的情况相比,泡沫铜孔密度为20 PPI、50 PPI和90 PPI时的平均耗气量分别提升了17.7%、28.7%和111.08%。提升泡沫铜孔密度一方面可以增加CO_(2)水合物的生成量,提升材料蓄冷能力;另一方面会延长合成时间,增加蓄冷循环的准备时间,间接增大系统空间体积和重量。

CO_(2) hydrate is considered as one of the most promising cold storage materials in the future due to its high latent heat value of 500 kJ/kg at constant low temperature.However,its high equilibrium pressure,slow formation kinetics and low thermal conductivity limit its application.In this paper,by introducing the thermodynamic accelerator tetrahydrofuran(THF),a significant effect on reducing the formation pressure of CO_(2) hydrate is found.When the mass fraction of THF is 0.32,the synthesis of CO_(2) hydrate can be achieved under temperature of-3°C and pressure of 0.6 MPa.In addition,supporting porous media with high thermal conductivity is combined with CO_(2) hydrate,and results show that compared with the condition without copper foam,the average gas consumption at 20 PPI,50 PPI and 90 PPI increases by 17.7%,28.7%and 111.08%,respectively.On the one hand,increasing the pore density of copper foam can increase the production rate of CO_(2) hydrate and improve the normalized cold storage density of materials.On the other hand,the synthesis time can be prolonged,increasing the preparation time of the cold storage cycle,which will indirectly increase the space volume and weight of the cold storage system.