通孔金属泡沫强化蓄冰实验研究
Experimental Study on Enhanced Ice Storage in Open？？Cell Metal Foams

为了研究通孔金属泡沫内嵌相变材料凝固过程特性及泡沫材料孔结构参数对凝固过程的影响,搭建了固液相变传热可视化测量系统,利用该系统就通孔铜泡沫强化蓄冰过程开展了实验研究。实时观测了凝固相界面的瞬态移动过程,测量了金属骨架表面和内嵌相变介质的实时温度,研究结果表明:铜泡沫可有效改善蓄冰后期传热恶化现象,大幅减少蓄冰时间,加入铜泡沫后,结冰所需时间与纯水工况相比减少为48.86％(孔密度为1 181 m-1,孔隙率为0.90)和60.97％(孔密度为1 181 m-1,孔隙率为0.97);铜泡沫的孔隙率对结冰过程影响较大,孔隙率为0.90的铜泡沫比孔隙率为0.97的铜泡沫中水完全凝固时间减少20％,而孔密度对结冰过程影响可忽略不计。可视化结果表明,未凝固相局部自然对流导致凝固相界面发生倾斜,呈现下部略快于上部的凝固界面。
To explore the heat and mass transfer characteristics during the phase change in metal foams, a test rig with solid/liquid phase change heat transfer visualization device was designed and established. The effects of pore structure parameters on solidification process were measured. Results show that the involvement of open？？cells in metal foam can significantly enhance the solidification process. The deterioration of phase change heat transfer can be compensated by the enhanced heat conduction with metal foam. The full solidification time can be reduced by 48？？86％ (pore density of 1 181 m-1 and porosity of 0.90) and 60.97％ (pore density of 1 181 m-1 and porosity of 0.97), respectively, in comparison with the case of pure water. Porosity plays a vital role in solidification process but the influence of pore density upon solidification can be neglected. The full solidification time can be further reduced by 20％ when the porosity decreases from 0.97 to 0.90. The visualization demonstrated an inclined solidification front, which indicated the contribution of local natural convection in the fluid phase. Local thermal equilibrium between metallic ligaments and the saturating PCM (distilled water) was experimentally observed