混合溶劑除濕液之熱物性質密度、黏度 及蒸氣壓量測

Vapor Pressures, Densities and Viscosities of Mixed-Solvent Desiccants

蔡志源(Chih-Yuan Tsai)

指導教授 ： 李夢輝

中原大學/工學院/化學工程研究所/碩士(2004年)

https://doi.org/10.6840/cycu200400387

摘要

液體除濕液已被廣泛的運用在移除空氣中的水氣，而液體除濕劑主要可分為無機鹽類與有機醇類水溶液，直到最近混合溶劑除濕液才被廣泛的討論。本研究為量測(LiCl or LiBr) / (PG or TEG) / H2O之密度、黏度及蒸氣壓，濃度範圍為鹽類(4-25 mass %)有機醇類為(50-80 mass %)，溫度為30到70℃。
對於醇類水溶液之密度與黏度採用Redlich-Kister equations 之過剩體積及過剩動黏度之模式來計算，而混合溶劑部分則是結合了鹽類濃度與溶劑在salt-free的情況下所延伸出的關係式來描述，而計算的結果是令人滿意的。在蒸氣壓部分，採用平均圓球近似法理論為基礎來描述溶液的蒸氣壓，並得到令人滿意的結果。
研究結果發現，鹽類的加入能有效的降低溶液的蒸氣壓，但卻造成黏度增加的問題，所以基於這兩種因素的考量，在此發現LiCl/PG/H2O為一較理想的除濕液組成。而本研究所得之密度、黏度及蒸氣壓數據更可作為設計除濕設備之基礎參考數據。

關鍵字

密度 ； 平均圓球近似法 ； 蒸氣壓 ； 黏度

並列摘要

The liquid desiccants are commonly used for absorbing moisture from air. Conventionally used liquid desiccants are aqueous solutions of either inorganic salts or organic compounds. The aqueous-organic with salt systems have been recently considered as potential absorbents for liquid desiccants. The thermodynamic properties such as density, viscosity, and vapor pressure of (LiCl or LiBr) / (propylene glycol or triethylene glycol) / H2O systems for temperatures ranging from 30 to 70 ℃ have been measured in this study. For each ternary system, four systems of which ( 4 - 25 mass % ) salt mixed with various glycols ( 50 - 80 mass % ) were studied.
The Redlich-Kister equations for the excess volume and the excess kinematic viscosity were used to model the measured density and viscosity of aqueous glycols. For the salt/glycol/H2O systems, an equation expressed as function of the molality of salt to calculate the difference between the property of the solution and the property of the salt-free aqueous glycol was developed. The results of the calculations of density and viscosity for salt/glycol/H2O systems are satisfactory. Incorporated with the pseudo-solvent approach, a vapor pressure model based on the mean spherical approximation for aqueous electrolyte solutions was used to represent the measured vapor pressure of salt/glycol/H2O systems. Satisfactory results were obtained for the vapor pressure calculations for salt/glycol/H2O systems.
When compared to the vapor pressures of conventionally used liquid desiccants, the vapor pressures of the aqueous-organic systems with salt yields smaller values of vapor pressures. On the other hand, the viscosity of salt/glycol/H2O is generally increasing with the molality of the salt. When consider both the vapor pressure and the viscosity of the solution, the LiCl/PG/H2O was found to be the best desiccant among four systems tested. The thermodynamics properties measured in this study can be used as the data base for design dehumidifier process using mixed-solvent desiccants as absorbents.

並列關鍵字

viscosity ； vapor pressure ； mean spherical approximation ； density

參考文獻

林麒峰，除濕劑新配方之蒸氣壓量測研究，中原大學化學工程研究所，2002年。

陳儷方，混合溶劑除濕液之蒸氣壓量測研究，中原大學化學工程研究所，2003年。

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