MATHEMATICAL MODEL OF PULSE-TUBE MICROCOOLERS

摘要

The absence of mechanical wear of moving parts and a low level of natural vibrations have made pulse-tube micro-coolers (PTM) highly competitive in the market of traditional cryogenic microsystems (CMS). At the same time, the lack of a generally accepted theory of the operating processes of PTMs complicates the design of CMSs of this class and necessitates a large amount of concomitant experimentation and research, which increases the designing costs. The computer models of a PTM and its individual elements, the pulse tube (PT) in particular, known from domestic and foreign publications provide a fairly general description of the operating processes, do not consider the hydraulic losses of the gas channel, and make a number of other assumptions that simplify the theoretical analysis. Those features substantially hinder the use of known computer models when designing PTMs and analyzing how the individual parameters of the cooler design affect its characteristics. Hence the urgent need to develop a PTM computer model that would make maximum allowance for the specific cooler design and satisfy the needs of developers and designers for a computer tool for designing PTMs of this class. The model is based on computer simulation of the processes whereby the working gas moves in the main elements of the PTM during the operating cycle and the attendant displacement of thermodynamic effects, including compression-expansion, heat input and removal in heat exchangers, and the hydraulic losses in the gas channel.