Mathematical Modelling and Design Software for Pulse Tube Cryocoolers

Abstract

Pulse tube refrigerators are increasingly become popular because of its higher reliability,absence of any moving parts at its cold end,easy design and fabrication technique, less maintenance,less wear and tear etc.However its design is quite complicated because of the complex heat and mass transfer process occurring inside it,so it is a challenging problem to the scientists and engineers pursuing this field to design pulse tube cryocoolers in order to achieve the desired performance.The work presented in this thesis is directed towards the detailed mathematical analysis of regenerator,a critical component of not only pulse tube cryocoolers but also all other types of regenerative cryocoolers.Based on the mathematical analysis,a software package has been developed for simulation of regenerator and validated with the experimental results available in the literature.Also,a parametric study has been performed to identify the effect of essential parameters that affect the cooling performance of the regenerator for cryogenic based applications.Detailed mathematical analysis of pulse tube refrigerator has been carried out for both Stirling and Gifford Mc-Mohan type pulse tube refrigerators of various geometrical configurations including different losses in various components that affect its performance.Based on the mathematical analysis,a general purpose simulation software package has been developed to design pulse tube refrigerators and validated with the numerical results available in previous results.Also,CFD analysis of inertance type pulse tube refrigerator has been carried out not only to visualise the inside fluid flow and heat transfer processes,but also to identify the essential changes that happen due to increase in operating frequency.The effect of various losses,those explained theoretically by various scientists,has been illustrated graphically in the present work.