Performance prediction of a long crossflow reverse osmosis membrane channel

Song, Lianfa; Tay, Kwee Guan

doi:10.1016/j.memsci.2006.03.026

Cited by 29 publications

(19 citation statements)

References 11 publications

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“…In addition to DNS results, we validate the present model against the experimental data of Song and Tay [26]. In their experimental study, a system of commercial RO elements (ESPA-2540) was investigated.…”

Section: Comparison To Experimental Datamentioning

confidence: 63%

Modeling reverse osmosis element design using superposition and an analogy to convective heat transfer

Rohlfs

Thiel

Lienhard

2016

Journal of Membrane Science

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Accurate models for concentration polarization (CP), the buildup of solutes at the membrane-solution interface in reverse osmosis (RO) channels, are critical for predicting system performance. Despite its empirical success, many modeling approximations employed in the derivation of the oft-used stagnant film model seem to limit the model's applicability to real systems. In addition, many existing models for CP use an average mass transfer coefficient with a local mass transfer driving force, which leads to incorrect predictions for the osmotic pressure at the membranechannel interface. In this work, we reduce the Zydney-transformed governing equations for solute mass transfer to an analogous convective heat transfer problem. We then apply the principle of superposition to fit solutions from the heat transfer problem to the RO channel boundary conditions, yielding a solution that correctly and consistently combines a local transport coefficient with a local mass transfer driving force. The resulting expression for RO element sizing and rating shows good agreement with experimental data and provides a theoretical basis for CP modeling that captures the characteristic growth of the mass transfer boundary layer not accounted for by many existing, more empirical models. The model has important consequences for the design of RO systems with high permeability membranes, as the decrease in membrane resistance in these systems leads to a relative increase in the importance of CP in system performance.

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Section: Comparison To Experimental Datamentioning

confidence: 63%

Modeling reverse osmosis element design using superposition and an analogy to convective heat transfer

Rohlfs

Thiel

Lienhard

2016

Journal of Membrane Science

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“…In order to validate the present work, we compare the numerical model results to experimental data collected by [33,[50][51][52]. In these experiments, a solution of sodium chloride is used as the feed solution.…”

Section: Comparison To Literature Datamentioning

confidence: 97%

“…It is apparent that the model predicts some data sets better than others. The data for which the model shows good agreement are: Van Wagner et al [50], who used NaCl and coupon sized membranes; Song et al [33], who used NaCl and spiral wound RO modules; and the low salt passage data from Prabhakar et al [51] data, who used NaCl and two different cellulose acetate membranes one of which had low salt passage (SP) (~10%) and another which had high SP (~50%). Salt passage is defined as the ratio of the module outlet product salinity to the inlet feed salinity.…”

Section: Comparison To Literature Datamentioning

confidence: 99%

“…Much research has been conducted on the physics of the solution-diffusion model [7,18,[20][21][22] and many numerical studies have been applied to account for the more complex effects of concentration polarization, salt diffusion, and fouling [23][24][25][26][27]. Other studies have applied the solution-diffusion model for the design of RO modules such as spiral wound, hollow fiber, and crossflow long channels [25,[28][29][30][31][32][33]. The solution-diffusion model has also been used together with relevant conservation laws to optimize the operation of RO systems and minimize the specific power consumption and cost of a plant [34][35][36][37][38][39][40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

“…Song and Tay [33] developed an analytical model of an RO exchanger based on the solution-diffusion model for transport across the membrane and conservation laws for a crossflow configuration; osmotic pressure was linearized, zero salt passage assumed, and hydraulic losses were neglected. They found good agreement with experiments that they performed as well.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effectiveness-mass transfer units (ε-MTU) model of a reverse osmosis membrane mass exchanger

Banchik

Sharqawy

Lienhard

2014

Journal of Membrane Science

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A strong analogy exists between heat exchangers and osmotic mass exchangers. The effectiveness -number of transfer units (-NTU) method is well-known for the sizing and rating of heat exchangers. A similar method, called the effectiveness -mass transfer units (ε-MTU) method, is developed for reverse osmosis (RO) mass exchangers. Governing equations for an RO mass exchanger are nondimensionalized assuming ideal membrane characteristics and a linearized form of the osmotic pressure function for seawater. A closed form solution is found which relates three dimensionless groups: the number of mass transfer units, which is an effective size of the exchanger; a pressure ratio, which relates osmotic and hydraulic pressures; and the recovery ratio, which is the ratio of permeate to inlet feed flow rates. A novel performance parameter, the effectiveness of an RO exchanger, is defined as a ratio of the recovery ratio to the maximum recovery ratio. A one-dimensional numerical model is developed to correct for the effects of feed-side external concentration polarization and nonlinearities in osmotic pressure as a function of salinity. A comparison of model results to experimental data found in the literature resulted in an average error of less than 7.8%. The analytical ε-MTU model can be used for design or performance evaluation of RO membrane mass exchangers. Keywords

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Reverse Osmosis

Song¹,

Liu²,

Liang³

2013

Encyclopedia of Membrane Science and Technology

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Recent theoretical progresses in the reverse osmosis (RO) desalination process were reviewed. The long RO channel as commonly used in desalination applications was modeled as a heterogeneous system in which the permeate velocity, crossflow velocity, and salt concentration are all variables along the membrane channel. Concentration polarization and energy consumptions in such a heterogeneous RO channel were rigorously quantified and analyzed. Examples were provided for the demonstrations or illustrations of the theoretical developments.

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Performance prediction of a long crossflow reverse osmosis membrane channel

Cited by 29 publications

References 11 publications

Modeling reverse osmosis element design using superposition and an analogy to convective heat transfer

Modeling reverse osmosis element design using superposition and an analogy to convective heat transfer

Effectiveness-mass transfer units (ε-MTU) model of a reverse osmosis membrane mass exchanger

Reverse Osmosis

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