Details

Autor(en) / Beteiligte

• Reimund, Kevin K.
• McCutcheon, Jeffrey R.
• Wilson, Aaron D.

Titel

Thermodynamic analysis of energy density in pressure retarded osmosis: The impact of solution volumes and costs

Ist Teil von

• Journal of membrane science, 2015-08, Vol.487 (C), p.240-248

Ort / Verlag

United States: Elsevier B.V

Erscheinungsjahr

2015

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• A general method was developed for estimating the volumetric energy efficiency of pressure retarded osmosis via pressure-volume analysis of a membrane process. The resulting model requires only the osmotic pressure, π, and mass fraction, w, of water in the concentrated and dilute feed solutions to estimate the maximum achievable specific energy density, u, as a function of operating pressure. The model is independent of any membrane or module properties. This method utilizes equilibrium analysis to specify the volumetric mixing fraction of concentrated and dilute solution as a function of operating pressure, and provides results for the total volumetric energy density of similar order to more complex models for the mixing of seawater and riverwater. Within the framework of this analysis, the total volumetric energy density is maximized, for an idealized case, when the operating pressure is π/(1+w−1), which is lower than the maximum power density operating pressure, Δπ/2, derived elsewhere, and is a function of the solute osmotic pressure at a given mass fraction. It was also found that a minimum 1.45kmol of ideal solute is required to produce 1kWh of energy while a system operating at “maximum power density operating pressure” requires at least 2.9kmol. Utilizing this methodology, it is possible to examine the effects of volumetric solution cost, operation of a module at various pressure, and operation of a constant pressure module with various feed. •Thermodynamic model based on initial states of the concentrated and dilute solutions.•Alternative expression of minimum energy for desalination and osmotic energy generation.•Minimum kmol of ideal solute per kWh in an osmotic energy generation.•Maximum total volumetric energy density and cost for idealized conditions.