Research On Forward Permeability Performance And Parameter Optimization Based On Flow Field Analysis Of Membrane Surface

The concentration polarization phenomenon often appears in the forward osmosis process.It causes the problem about attenuation of flux and has a negative impact on the performance of osmosis.Combining numerical simulation with experimental method,the liquid velocity and pressure contours upon the membrane at the different inlet velocities and various spacer configurations were analyzed to improve the flow distribution and achieve the optimization procedure of forward osmosis process.First of all,the performance of forward osmosis process was researched when the osmotic pressure difference(ranging from 2 MPa to 8 MPa),hydraulic pressure(ranging from 0 MPa to 0.2 MPa)and flow pattern have been changed.The results show the flux can increase by a large margin with the increase of the osmotic pressure difference and hydraulic pressure.However,the latter is easier to produce the concentration polarization phenomenon.There exists a best performance in the forward osmosis when the osmotic pressure difference is no more than 5.36MPa.In addition,the flow pattern has a weak effect on performance of osmosis process.Furthermore,the liquid velocity and pressure contours upon the membrane at the different inlet velocities(0.23 m/s,0.31 m/s,0.40 m/s,0.55 m/s and 0.66 m/s)was analyzed combining numerical simulation with experimental method.As a consequence,small high-velocity area was present at low inlet velocity.It could cause the serious concentration polarization phenomenon.However,the higher inlet velocity causes extra consumption of energy in the forward osmosis process.The optimal inlet velocity was 0.55 m/s.In addition,the spacer configurations were studied by analyzing the flow distribution.As a result,spacers were evenly distributed in the channel and the optimum spacer configuration was existed when the spacers were 1 mm away from the membrane.It is beneficial to alleviate ECP in the osmosis process.