Application of hydrocarbon mixtures in small refrigerating and cryogenic machines

Application of an ejector in autocascade refrigeration cycle for the performance improvement

“…HFC candidates like R32, R134a, R152a, and R23 can be a choice in a range of temperature. Naer and Rozhentsev (2002) investigated the application of hydrocarbon mixtures in small refrigerating and cryogenic machines, one of which employed the autocascade refrigeration cycle with one liquid phase separator. Their research results demonstrate that small, single stage, sealed, lubricated compressors can be applied to microcoolers for the temperature range of À73 C to À183 C. Kim and Kim (2002) investigated the performance of an autocascade refrigeration system using zeotropic refrigerant mixtures of R744/R134a and R744/R290.…”

First and second law analysis of an ejector expansion Joule-Thomson cryogenic refrigeration cycle

“…Kornhauser [10] has studied the thermodynamic performance of the ejector expansion refrigeration cycle using R-12 with a constant mixing pressure model, showing a COP improvement of as high as 21% over the standard cycle under standard operating conditions. On the other hand, vibrating-free Joule-Thomson (JT) cryocoolers have been largely used for astronautical applications, infrared detectors, cryosurgical probes, cryo-preservation, gas chiller or liquefaction and water vapor cryo-trapping owing to their quick 'cool down' characteristics, simple structure and applicability in a range of 70-200 K. Experimental investigations with JT micro-coolers in the range of 90-200 K were conducted by Naer and Rozhentsev [11] for hydrocarbon mixtures. Yu [12] proposed a new refrigeration cycle for improving the performance of a small JT cryocooler by applying an additional ejector instead of throttling valve and capillary tube, showing that the performance can be significantly improved based on the presented ejector expansion Joule-Thomson (EJT) cycle.…”

Investigation of the starting modes of the low-temperature refrigerating machines working on the mixtures of refrigerants

“…The modern compressors of this type have well-known limitations on the maximum discharge pressure of about 25 bar, compression ratio of (12, ., 15) and compressor capacity. Under these limitations the conventional MR J-T refrigerating systems are of modest cooling capacity, small-sized and the working temperature tends to range within (À80, ., À100) C for the systems operating by the Linde cycle and down to À200 C for the Kleemenko cycle (Alexeev, 2002;Boiarski et al, 1998;Boiarski et al, 2001;Naer and Rozhentsev, 2002;Weckemann and Oellrich, 2003). Despite the low temperatures, steady-state operating pressure and the compression ratio of the refrigerant in a well-designed MR refrigerating machine still meet the hydraulic requirements of the hermetic compressor thus increasing the system reliability and operating life (Gurudath Nayak et al, 2007).…”