Mixed Refrigerant Joule-Thomson (MRJT) cryocooler for medical applications

Mixed Refrigerant Joule-Thomson (MRJT) cryocooler have shown great potential for cooling temperature above 80 K after the introduction of refrigerant mixtures in JT cryocoolers. These make them suitable for various medical cooling applications, where biological samples are to be stored below -80 °C. MRJT cryocoolers use conventional refrigeration and air conditioning components and have no moving parts at the cold end making them simple compared to other cryocoolers. At temperature above 150 K, MRJT cryocoolers are a great alternative to Stirling and Pulse Tube cryocooler due to their simplicity and cost effectiveness. In the present work, keeping in mind the medical industry, MRJT cryocooler for -100 °C and -130 °C applications are developed. The working fluid is a refrigerant mixture consisting of common hydrocarbons in an optimized proportion. Based on the studies, it is found that a no load temperatures of -110 °C and -133 °C are obtained using two different refrigerant mixtures, Mix 1 and Mix 2. In addition to this, cooling effect of 50 W is obtained at -100 °C and -130 °C using refrigerants Mix 1 and Mix 2 respectively. Furthermore, by increasing the charging pressure of Mix 1, no load temperature reduced to -120 °C while 50 W of cooling effect was obtained at -107 °C.