Modeling electrolyte solution in simscape

Hello,

I'd like to move a model that I've been working on to Simulink. It's a thermochemical model where the working fluid is an electrolyte solution (ex: lithium chloride and water). I was considering using the Simscape environment to take advantage of the existing library of heat exchangers, pumps, etc. but I don't see a clear way to model a solution where the concentration is variable.

The thermal liquid library does not seem quite right as it appears to base the fluid properties on pressure and temperature. For this electrolyte solution, I would define properties based on pressure, temperature, and concentration. Since the concentration of the fluid changes during the process, I would not want have to make many blocks for each different concentration. Are there any good ways to do this?

Thank you!

Answer 1

[Yifeng Tang]

Hi Jacob,

You are correct: the thermal liquid domain will not allow you to keep track of the concentration. Two potential solutions I can think of:

1. Use a physical signal on the side to keep track of the concentration. You may design the model so that a physical signal is there with every thermal liquid block. Some add/subtract/integrator blocks will allow you to simulate the change in the concentration due to flow or electrochemical processes. The down side may be (1) that it's clumsy; lots of signals flying around, and (2) can't model solution properties like viscosity as functions of the concentration (if that matters).
2. Build a new physical domain based on the thermal liquid domain. Add a new across variable for the concentration, and a through variable for the LiCl flow. It's going to take some work, but will be a more elegant solution for your "solution" :p. A potential challenge is that you will need to replace all fluid property look-ups in the TL domain to include another dimension for the concentration. Not sure if there is such infrastructure already. If you don't care about other fluid properties (like viscosity) change as a function of concentration, things may be easier.

I suggest that you reach out to MathWorks support or your sales person to get connected to more resources, if you haven't already done so.