Optimum Control Program for Helium Recovery System Based on Thermal Equation

Abstract

Nowadays, liquid helium is one of essential resource for modern civilization in which it is utilized to cool down the superconducting magnet devices in various fields, such as magnetic resonance image (MRI), nuclear magnetic resonance (NMR) spectroscopy, and research on nuclear fusion reactor, etc. However, unfortunately, the helium resource is very limited on Earth. Therefore, one has been looking for the way to minimize loss and consumption of helium in those application. As an idea, a system is suggested to trap the evaporating helium gas and liquefy liquid helium, so called helium recovery system or helium recovery plant. A couple of companies have manufactured helium recovery system for laboratory/hospital and helium recovery plant for the large facility. The helium recovery system liquefies using the 4K cryocooler so that it can be operated in the relatively small space. However, its conventional operation needs constant cooling down with the cryocooler, which causes high maintenance cost about $30,000 in a year. Thus, new control method is required to reduce cost of the maintenance of the helium recovery system. We designed IoT (Internet of Things) based program to extend effective lifetime of the cryocooler. The program optimizes operation time of the cryocooler using thermal equations of the liquefaction system. In addition, it displays real-time status of the cryocooler. Eventually we demonstrate to extend the lifetime of cryocooler up to 300%.