Return Flow Ion Concentration Polarization System
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electrodialysis and ion concentration polarization (ICP) desalination systems face challenges with high energy consumption due to chaotic electroconvection in dilute streams and salt propagation from concentrate streams, leading to inefficient salt removal and increased energy dissipation.
Innovation Solution
The implementation of a return flow ICP desalination system, which incorporates a porous membrane to create a flow barrier that suppresses chaotic electroconvection and prevents salt propagation, allowing for cross-current flow and increased dwell time of the feed stream, thereby enhancing energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional electrodialysis or ICP desalination systems are used, then salt removal can be achieved, but chaotic electroconvection occurs in the dilute stream and salt propagates from the concentrate stream, leading to high energy consumption
Solution Approach 1:
A porous membrane is introduced as an intermediary flow barrier between the dilute and concentrate streams. This membrane allows ions to pass through while restricting chaotic fluid mixing, thereby maintaining salt removal efficiency while reducing energy consumption associated with electroconvection and salt back-propagation
Solution Approach 2:
The patent employs a porous membrane with specific pore structures that enable selective flow control. The porous structure allows ionic transport while creating a physical barrier that suppresses chaotic electroconvection in the dilute stream and prevents enriched salt from propagating back into the dilute stream, thus resolving the energy efficiency contradiction
2Manufacturing precision
If high current density is applied to achieve highly desalted and concentrated water streams, then salt removal ratio increases, but chaotic electroconvection and salt propagation occur, increasing energy consumption
Solution Approach 1:
The porous membrane acts as a mediator that enables the system to operate at high current densities without the adverse effects of chaotic electroconvection and salt back-diffusion. By introducing this intermediary structure, the patent achieves high salt removal ratios while avoiding the energy penalties that would normally accompany high current operation
Solution Approach 2:
The patent changes the flow regime parameters by introducing the porous membrane, which fundamentally alters how the dilute and concentrate streams interact. This parameter change allows the system to operate in a regime where high current density can be applied without triggering chaotic electroconvection, thus achieving high salt removal with lower energy consumption
3Device complexity
If the dilute and concentrate streams are on the same channel component without restrictions, then system complexity is reduced, but the streams can affect each other, causing decline in salt removal efficiency
Solution Approach 1:
The porous membrane serves as a subtle intermediary that maintains stream separation without requiring complex alternating membrane structures. This single-component barrier prevents stream interaction and maintains salt removal efficiency while keeping the channel structure relatively simple
Solution Approach 2:
Rather than changing the entire channel structure, the patent applies a localized modification by introducing a porous membrane at specific locations where stream interaction would be most problematic. This local quality change achieves reliable salt removal without substantially increasing overall device complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces energy consumption by minimizing chaotic flow mixing and salt propagation, improving salt removal efficiency and increasing the effectiveness of desalination processes for a wide range of brine and contaminated streams.
Implementation Method 1
The porous membrane allows fluid to flow partially by a pressure difference but also allows ions to freely pass through
Implementation Method 2
The porous membrane allows fluid to flow partially by a pressure difference but also allows ions to freely pass through
Implementation Method 3
The return flow channel is configured within the primary channel to allow a feed stream to enter the channel through an inlet, flow along the primary channel to the distal end of the channel, and at least a portion of the feed stream to flow into the return flow channel and back towards the inlet end of the channel
Implementation Method 4
Ion concentration polarization (ICP) desalination systems have been described... in ICP desalination, both dilute and concentrate streams are separately acquired between two identical ion exchange membranes (IEM)
Data Source
AI summary
A device for purifying and/or concentrating a first water stream containing ionic impurities includes a first and second ion exchange membrane and a first porous membrane. The ion exchange membranes have the same charge, and a channel into which the first water stream can be directed is defined between the first and second ion exchange membranes. The channel has an inlet end and a return flow end and comprises a first and second outlet. The inlet and at least the first outlet are located on the inlet end of the channel and are separated by the first porous membrane that traverses the length of the channel between the ion exchange membranes and terminates at a return flow zone that is at least partially closed. At least part of the first water stream flows through the first porous membrane, joining a first return flow stream.