Macroscopic fluid flow conditions in spiral wound membrane elements: packed bed approach

The modelling of the reverse osmosis process is needed to fully evaluate it s potential and facilitate scale up. The definition of the flow regime in t he concentrate channel is of paramount importance. The present paper descri bes our experimental investigations on RTD and relates the RTD response cur ves to the regime of flow in the concentrate channel. Results demonstrate ( i) that dead zones are present; (ii) that both a Plug Flow with Dispersion (PFD) and Probabilistic Time Delay (PTD) model can be used to characterise the flow; and (iii) that PFD- and PTD-model parameters assume nearly consta nt Values for a given geometry which simplifies the prediction of the RTD f or any desired flow rate.