Simulating isentropic expansion in MATLAB

[Erik]

Hi all,

I'd like to simulate isentropic expansion in the MATLAB version of Cantera. I want to expand the gas isentropically from the exhaust valve of an internal combustion engine piston to ambient conditions. I'm a little confused on which reactor and flow device combination to use to achieve this. The model I have now simulates an ideal gas in a piston where gas properties change over time every cycle, but I want to then take that gas and expand it to ambient conditions. Would it be better to use two reactors in a ReactorNetwork, or to run the piston simulation, extract the data, then run a separate expansion simulation?

Thank you,

Erik

[Bryan Weber]

Hi Erik

Are you assuming this is a quasi-equilibrium expansion or do you need to model the kinetics throughout? If the former, you can simply use the Solution object and set the entropy and another state property (T, P, rho) in a process that models the expansion. If the latter, you'll need to set up a Reactor with customized governing equations to solve the relevant set of ODEs, there's not a model built-in to Cantera which can do that.