Flow Battery

From Cell to Stack to System

Flow batteries separate the storage of electrical energy from the charge/discharge process; power and energy can be scaled independently of each other to meet the needs of many different applications. Very few technologies are realistically applicable to utility-scale electrical energy storage (EES); flow batteries are in an elite category. But they are also scalable to home and building applications for peak shaving or peak shifting, or for emergency backup power.

In a flow battery, energy storage is accomplished in arbitrarily large tanks full of electrolytes, while separate stacks of cells convert electricity into and out of different electrochemical (redox) states of those electrolytes. The tank on the left contains the catholyte, and the tank on the right contains the anolyte.


By Nick B, benboy00 - https://commons.wikimedia.org/wiki/File%3ARedox_Flow_Zelle_Deutsch_Farbverlauf.png, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=35143999

Of course, the single cell in the above diagram is actually a stack of about 14-19 cells in a real battery, a few of which are shown expanded below with both the membrane (typically DuPont NafionTM 117) and the porous graphite fiber electrode pads visible.

The charge collector plates also contain a serpertine "flow field" in the picture below, which is used to assure uniform distribution of electrolyte within the cell for minimum overpotential and reduced pumping losses.

There are many such plates in a stack, and many stacks are then plumbed in parallel in a battery. Time scales within a cell are on the order of fractions of a second, but any simulation of a flow battery must cover many days of charge/discharge scenarios.

This means that the complexities of modeling a realistic flow battery involve more than just combining fluid flow, thermal energy, electrical networks, and electrochemical treatment of redox reactions. They must also involve handling multiple time and distance scales simultaneously: you need to be able to zoom in on the fast time-scale multiphysics within a cell, while at the same time zooming out to the full system as it moves through its daily operational cycle.

Vanadium Redox Flow Batteries (VRFB) represent the current state-of-the-art, with 20+ years of reliable and safe operation demonstrated. Many research projects are underway to find alternate electrochemistries or membranes, or to reduce the cost and increase the performance of VRFBs.

Or just enjoy the diurnal variations of temperature gradients within a single cell of a 17-cell stack in a 6-stack battery over the course of a typical day:

 

Click here to fetch the VRFB case study on our User Forum

 

FloCAD online training

Class times: May 2 & 4 from 10am to 2pm MT

Cost: $425

This online class will provide an introduction to fluid modeling components within FloCAD. The class will be held over a 2-day period, with daily sessions running approximately 4 hours each. The class uses a mixture of lecture, demonstrations, and self-paced tutorials to allow attendees to practice building fluid system models and interpreting results. The presentations will comprise 2 - 3 hours of each session, and the instructor will be available during the remainder of the time for questions during tutorials. Attendees must have basic working knowledge of SINDA and Thermal Desktop as these topics will not be covered but their usage is required for FloCAD.

Register here

Thermal Desktop, RadCAD, and TD Direct in-class training

Date: April 25-28, 2017, 8:00 a.m. to 5:00 p.m., daily
Location: Lakewood, CO

CRTech will be hosting introductory training for Thermal Desktop, RadCAD and TD Direct. Lecture and hands-on tutorials introduce attendees to basic Thermal Desktop and RadCAD usage and allow practice building models and interpreting results. The class will also introduce students to SpaceClaim direct modeling CAD interface and advanced meshing tools in TD Direct.

Daily Schedule

Day 1 and 2: Introduction to SINDA and Thermal Desktop
Day 3: Introduction to RadCAD
Day 4: Introduction to TD Direct
 

To learn more about this class and to register, visit our Training Page.

Anode and cathode of a flow battery

Using Sinaps? It is not too soon to get started with TD/FloCAD!

This webinar describes the process for converting from Sinaps to Thermal Desktop (TD) and FloCAD. This process includes using an exporter which works with Version 6.0 of the CRTech tool suite (expected to be released in May of 2017).

Come learn about the basics of TD/FloCAD, including many compelling features not available in Sinaps. The webinar will also cover how to manage the transition period, during which you may be using both programs simultaneously. This is also a chance to ask questions. 

If you missed this webinar, please contact us for the presentation material and recording.