MATLAB Simulations of the Helium Liquefier in the FREIA Laboratory

TL;DR

This paper presents MATLAB-based simulations of a helium liquefier system, modeling components with matrices and thermodynamic properties with CoolProp, achieving accurate yield predictions.

Contribution

It introduces a matrix-based simulation approach for the helium liquefier, incorporating non-linear Joule-Thomson valve modeling and realistic thermodynamic data.

Findings

Simulation matches observed helium yield

Effective modeling of heat exchangers and valves

Rapid solution convergence

Abstract

We describe simulations that track a state vector with pressure, temperature, and gas flow through the helium liquefier in the FREIA laboratory. Most components, including threeway heat exchangers, are represented by matrices that allow us to track the state through the system. The only non-linear element is the Joule-Thomson valve, which is represented by a non-linear map for the state variables. Realistic properties for the enthalpy and other thermodynamic quantities are taken into account with the help of the CoolProp library. The resulting system of equations is rapidly solved by iteration and shows good agreement with the observed LHe yield with and without liquid nitrogen pre-cooling.