Wettability-Based Flow Splitters

The presented technique is suitable for use in microscale equipment, in which surface tension forces, rather than gravitational force, dominate. 

The wettability based separation of two immiscible liquids is explained in more detail for the membrane separator [72]. 

The pressure drop in the separator outlets should be identical because the two-fluid streams exit at the same ambient pressure (Equation 7.58). However, it is proposed that the design of the microseparator should be based on a worst case criteria where the pressure drop in dispersed phase outlet should be calculated on the total flow rate [72]. 

The pressure drop in the chaimel (connected to membrane) on the aqueous side of the separator devices is given by  

In most practical situations the pressure drop in the separator will be small compared to and can be neglected  

---

In order to separate the two phases online an in-house flow splitter was connected at the end of each test section (Fig. 3.6). The splitter had two side channels made of stainless steel and PTFE that have different wettabilities for the two liquids used. The internal diameter and the length of the side channels were chosen based on the pressure drop that was created on the flow splitter [similar to (Scheiff et al. 2011)]. With this configuration pure ionic liquid phase was obtained from the PTFE outlet and aqueous solution from the stainless steel outlet. However, at high mixture velocities the separation was not always 100 % efficient and a mixture of ionic liquid and aqueous solution was collected from the steel outlet. 

Figure 7.17 Schematics of different types of flow splitters for separation of liquid-liquid two-phase flow, (a) Geometrical modifications (e.g., Y-separator), (b) wettability based (e.g., membrane separator), and (c) gravity based separator (e.g., settler).

---