Affiliation:
1. Department of Mechanical Engineering,Massachusetts Institute of Technology,Cambridge, MA 02139-4307
Abstract
Abstract
Proper evaluation of the Gibbs free energy and other properties of seawater and other aqueous solutions is essential in the analysis of desalination systems. Standard seawater has been studied extensively and property data are readily accessible. However, many aqueous solutions requiring desalination have significantly different compositions from seawater and seawater data are generally not accurate for these solutions. Experimental data for a given aqueous solution may be unavailable under the conditions of interest. Therefore, there is a need to model relevant physical properties from chemical thermodynamic principles. In particular, for solutions that are not ideal, the activity and fugacity coefficients must be considered. In this paper, the effect of nonidealities in sodium chloride (NaCl) solutions is considered through a parametric study of the least work of separation for a desalination system. This study is used to determine the conditions under which the ideal solution approximation is valid and also to determine when an NaCl solution is a good approximation to standard seawater. It is found that the ideal solution approximation is reasonable within ranges of salinities and recovery ratios typical of those found in the seawater desalination industry because many of the nonidealities cancel out, but not because the solution behaves ideally. Additionally, it is found that NaCl solutions closely approximate natural seawater only at salinities typically found in seawater and not for salinities found in typical brackish waters.
Subject
Geochemistry and Petrology,Mechanical Engineering,Energy Engineering and Power Technology,Fuel Technology,Renewable Energy, Sustainability and the Environment
Reference40 articles.
1. Cooper, J. R., 2008, “Release on the IAPWS Formulation 2008 for the Thermodynamic Properties of Seawater,” The International Association for the Properties of Water and Steam, September, pp. 1–19.
2. A Gibbs Function for Seawater Thermodynamics for −6 to 80 °C and Salinity up to 120 g kg−1;Deep-Sea Res., Part I,2008
3. The Practical Salinity Scale 1978: Conversion of Existing Data;Deep-Sea Res., Part I,1981
4. Thermophysical Properties of Seawater: A Review of Existing Correlations and Data;Desalination Water Treat.,2010
5. Thermodynamic Cycle Analysis for Capacitive Deionization;J. Colloid Interface Sci.,2009
Cited by
29 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献