硅胶孔径对吸附剂吸湿性能及制冷特性的影响

为开发出一种适用于吸附制冷的高性能吸附剂,选择了3种不同孔径的商用硅胶,孔径分别是2～3、4～7、8～10 nm,利用浸泡的方法将氯化钙嵌入硅胶微孔内来制备复合吸附剂,并对吸附剂的吸附性能进行了实验测试.测试结果表明:对于2～3 nm的硅胶,由于孔径较小,氯化钙的浸入堵塞或者部分堵塞了水进入硅胶的传质通道,导致复合吸附剂不论是吸附量还是吸附速率与纯硅胶相比都没有提高;而对于4～7 nm和8～10 nm的硅胶,其复合吸附剂不论是吸附量还是吸附速率都较其相应的纯硅胶有大幅提高.复合吸附剂在20%湿度下吸附20 min和2 h的吸附量分别是8.08 g/100 g和15.7 g/100 g,在同等工况下,纯硅胶的吸附量分别是1.96 g/100 g和2.0 g/100 g.用制备的复合吸附剂制作了一台小型吸附制冷机并进行了测试,当热源温度为90℃,冷却水温度为35℃时,在整个循环周期内(15 min),制冷功率为1.03 kW,单位质量吸附剂的制冷功率(SCP)为128.3 W/kg,性能系数(COP)为0.27.

空气取水用硅胶/MgCl_(2)复合吸附剂吸附性能研究

通过浸渍法合成了一种硅胶/MgCl_(2)新型复合材料。探究了球型硅胶孔径和粒径、MgCl_(2)溶液浓度、吸附环境温湿度对硅胶/MgCl_(2)复合吸附剂吸附性能的影响。实验表明,复合吸附剂的吸附能力与硅胶孔径成正比,与硅胶粒径成反比。在25℃、50%RH下,SG-A/M20、SG-B/M20、SG-C/M20的平衡吸附量分别为0.25,0.37,0.39 g/g;在25℃、35%RH下,SG-D/M20、SG-A/M20、SG-E/M20的平衡吸附量分别为0.21,0.16,0.14 g/g。RH为35%~80%时,复合吸附剂的吸附量随RH增大而增大,温度为25~35℃时,复合吸附剂的吸附量随温度升高先增大后减小。在25℃、RH 80%下,SG-B/M20取得最大吸附量0.58 g/g。复合吸附剂在110℃下脱附90 min水蒸气脱附率>98%。SG-B/M20、SG-C/M20具有良好的循环稳定性,经8次吸附-脱附循环后吸附量减小量<0.03 g/g。硅胶/MgCl_(2)复合吸附剂的水蒸气吸附性能探究,为硅胶基复合材料在空气取水领域的应用提供数据参考。

INVESTIGATION OF THE INTERACTIONS BETWEEN WATER AND MODIFIED SILICA GEL BY IGC AND TPD

In this work, the thermodynamic parameters for the adsorption of water vapor on untreated silica gel and silica gel treated with hygroscopic salts and silane coupling agent were determined by lnverse Gas Chromatography （IGC） in the infinite dilution region. The desorption activation energies of the water vapor on virgin and modified silica gels were estimated by using the Temperature Programmed Desorption （TPD） technique. The interactions between the water and the virgin and modified silica gels were discussed. Results showed that the thermodynamic parameters and desorption activation energy of water vapour on the silica gels increase with decreasing pore size and increasing the surface hydrophilic properties. The desorption activation energy of virgin and modified silica gels was found to increase with increasing the thermodynamic parameters. The larger the adsorption parameters and the desorption activation energy were, the interactions between water and virgin and modified silica gels were.