Modelling, Simulation and Control of Cryocooler/Cryo-systems

Abstract

Cryogenics is the experimental application of cryogenic principles to freeze and preserve recently deceased humans. The hope is that they may be revived in the future through new as yet undiscovered, medical technologies. Cryocooler are used in military for surveillance and missile guidance to cool down or maintain the temperature of the sensor. Cryocoolers offer reliable and maintenance free operation. No Cryogen requirement. The cost of cryogen is increasing, whereas the cost of cryocooler is decreasing. Cryocooler in space application is used to cool the focal point of the lens used for viewing the celestial objects which gets to a very high temperature due to the direct radiation from the space objects. There is a scope for new technology which would advance development towards invisible cryogenics.

In this project, it is proposed to first understand the working of all Cryocoolers. Next, to develop a mathematical model of specific Stirling Cryocooler based on ideal Stirling cycle. Mathematical model also includes dynamics of regenerator and linear compressor. The developed model on MATLAB/SIMULINK Platform is to be validated and tuned with the data from actual working laboratory setup of cryocooler. Temperature of the cold tip (source) is the primary target to be controlled in the cryocooler, for that the strategy to manipulate the stroke length of the compression piston is to be developed e.g. Conventional PID and some advance control scheme. The model simulator and control strategy is to be validated with the help of available experimental data. It is also proposed to develop a vibration model of stirling cryocooler to analyse the effect of harmonics on cold tip temperature.