Zhang Haiquan, Yuan Yanping, Sun Qingrong, Cao Xiaoling, Sun Liangliang
School of Mechanical Engineering, Southwest Jiaotong University, 610031 Chengdu, China.
Sci Rep. 2016 Sep 29;6:34115. doi: 10.1038/srep34115.
Green CaCl-based chemical sorbent has been widely used in sorption refrigeration, air purification and air desiccation. Methods to improve the sorption rate have been extensively investigated, but the corresponding theoretical formulations have not been reported. In this paper, a sorption system of solid-liquid coexistence is established based on the hypothesis of steady-state sorption. The combination of theoretical analysis and experimental results indicates that the system can be described by steady-state sorption process. The steady-state sorption equation, μ = (η - γ) , was obtained in consideration of humidity, temperature and the surface area. Based on engineering applications and this equation, two methods including an increase of specific surface area and adjustment of the critical relative humidity (γ) for chemical sorbents, have been proposed to increase the sorption rate. The results indicate that the CaCl/CNTs composite with a large specific surface area can be obtained by coating CaCl powder on the surface of carbon nanotubes (CNTs). The composite reached sorption equilibrium within only 4 h, and the sorption capacity was improved by 75% compared with pure CaCl powder. Furthermore, the addition of NaCl powder to saturated CaCl solution could significantly lower the solution's γ. The sorption rate was improved by 30% under the same environment.
基于氯化钙的绿色化学吸附剂已广泛应用于吸附式制冷、空气净化和空气干燥领域。人们对提高吸附速率的方法进行了广泛研究，但尚未报道相应的理论公式。本文基于稳态吸附假设建立了固液共存的吸附体系。理论分析与实验结果相结合表明，该体系可用稳态吸附过程来描述。考虑到湿度、温度和表面积，得到了稳态吸附方程μ = (η - γ)。基于工程应用和该方程，提出了两种提高吸附速率的方法，即增加化学吸附剂的比表面积和调整临界相对湿度(γ)。结果表明，通过在碳纳米管(CNTs)表面包覆氯化钙粉末，可以得到具有大比表面积的CaCl/CNTs复合材料。该复合材料仅在4小时内就达到了吸附平衡，与纯氯化钙粉末相比，吸附容量提高了75%。此外，向饱和氯化钙溶液中添加氯化钠粉末可显著降低溶液的γ。在相同环境下，吸附速率提高了30%。
