Department of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea.
Department of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea.
Water Res. 2021 Apr 1;193:116882. doi: 10.1016/j.watres.2021.116882. Epub 2021 Jan 28.
Hydrate-based desalination (HBD), a type of freezing-based desalination, can concentrate salts of saline water and produce fresh water via hydrate crystal formation. In this study, the thermodynamic stability, crystallographic information, and kinetic growth behavior of HFC-152a hydrate were investigated to estimate the desalination efficiency of HBD. The phase equilibria revealed that the HFC-152a hydrate could be formed at a higher temperature in the presence of NaCl (0 wt%, 3.5 wt%, and 8.0 wt%) than the HFC-134a hydrate at 0.3 MPa. The hydration number of the HFC-152a hydrate (sI) was found to be 7.74 through the Rietveld refinement of the powder X-ray diffraction patterns, and it was also used to determine the dissociation enthalpy of the HFC-152a hydrate. The Hu-Lee-Sum correlation was employed to predict the equilibrium shift and hydrate depression temperature of both HFC-152a and HFC-134a hydrates in the presence of NaCl. Faster hydrate growth kinetics and higher hydrate conversion were observed for the HFC-152a hydrate in saline solutions despite the smaller initial driving force at 0.3 MPa and the subcooling temperature of 3 K. Additionally, to quantify the desalination efficiency of the HFC-152a HBD, the maximum achievable salinity and maximum water yield were examined using the HLS correlation. The salt-enrichment efficiency decreased with an increase in the initial salinity and increased with increasing the subcooling. The overall results indicate that HFC-152a is, potentially, a superior candidate for HBD. The novel approach examined in this study will be useful for assessing the desalination efficiency of the HBD process.
水合基淡化（HBD）是一种基于冷冻的淡化方法，可通过水合晶体形成浓缩盐水的盐分并生产淡水。在这项研究中，研究了 HFC-152a 水合物的热力学稳定性、晶体学信息和动力学生长行为，以估算 HBD 的脱盐效率。相平衡表明，在 0.3 MPa 下，存在 NaCl（0wt%、3.5wt%和 8.0wt%）时，HFC-152a 水合物可以在较高温度下形成，而 HFC-134a 水合物则不能。通过粉末 X 射线衍射图谱的 Rietveld 精修，确定了 HFC-152a 水合物（sI）的水合数为 7.74，并利用其确定了 HFC-152a 水合物的离解焓。采用 Hu-Lee-Sum 关联式预测了 NaCl 存在下 HFC-152a 和 HFC-134a 水合物的平衡位移和水合物降压温度。尽管在 0.3 MPa 和 3 K 的过冷温度下初始驱动力较小，但在盐溶液中 HFC-152a 水合物的水合动力学更快，水合物转化率更高。此外，为了量化 HFC-152a HBD 的脱盐效率，使用 HLS 关联式考察了最大可达盐度和最大产水量。盐浓缩效率随着初始盐度的增加而降低，随着过冷度的增加而增加。总体结果表明，HFC-152a 可能是 HBD 的理想候选物质。本研究中考察的新方法将有助于评估 HBD 工艺的脱盐效率。
