A THERMODYNAMIC MODEL FOR THE EFFECT OF THERMAL BOUNDARY RESISTANCE ON MULTISTAGE THERMOELECTRIC CRYOGENIC REFRIGERATORS

摘要

New efforts are underway to develop thermoelectric materials for cooling of infrared detectors at cryogenic temperatures. In this study, a control thermodynamic model of multistage Thermoelectric (TE) cryocoolers is developed that includes the effect of heat transfer between the cryocooler and the thermal reservoirs as well as thermal resistance between the stages. It is assumed that a reservoir at 80 K is available and a cooling load at about 35 K, typical of the second stage of conventional cryocoolers, is desired. It is shown that under the assumption of availability of TE materials with a reasonably high figure of merit, a multistage TE cryocooler is required. As an example, a control thermodynamic model of a four-stage TE cryogenic refrigerator is developed. The effect of thermal conductance of the heat exchangers at the hot and cold sides of the refrigerator, the thermal resistance between the stages and the effect of the figure of merit of the TE material on the cooling capacity and efficiency of the multistage TE cryocooler is presented. The thermal design challenges of the development of multistage TE cryocoolers with high efficiency for cryogenic applications including the effect of heat leak are discussed.