Controlling the reliability performance of a thermoelectric cooler under variable heat load

Abstract

The work is devoted to substantiation of possibility of reduction of failure rate of thermal mode support system when operating with variable load by control of reliability indicators of thermoelectric cooler. A mathematical model for evaluating the effect of variable thermal load on reliability indicators of a single-cascade thermoelectric cooler at a given temperature level of cooling, medium temperature, geometry of thermocouple branches for various current modes of operation is considered. The relationship between the cooler steady-state operation time and mass and heat capacity of the structure, relative operating current and temperature difference is presented. The results of thermal load relation with operating current, refrigerating factor, time to steady-state mode, energy input, heat dissipation capacity of the radiator, and relative failure rate are presented. Calculations have been made at a given cooling temperature level, medium temperature, temperature differential, and thermocouple branch geometry for various characteristic current operating modes. It is shown that with decreasing thermal load at a given design of thermoelectric cooler, the value of operating current decreases, thus increasing the probability of no-failure operation. The obtained relationship of thermal load with operating current and relative failure rate serves as primary information for design of thermoelectric system for providing thermal modes of thermally loaded elements with variable thermal load. Using the rate of change of temperature difference between the thermally loaded element and the cold electrode of the cooler as a control feature, it is possible to reduce the failure rate when the thermal load decreases, which contributes to increasing the average probability of no-failure operation.