Thermal Brownian refrigerator with external and internal irreversibilities

Abstract

In this paper, a new model of irreversible thermal Brownian refrigerators considering external and internal irreversibilities is established by using finite time thermodynamics. The analytical formulas of cooling load and coefficient of performance (COP) are derived with Newtonian heat transfer law. The operating temperatures of the refrigerator are obtained by solving equations, and the basic performance characteristics and valid working areas are studied. The optimal performance is achieved by optimizing the design parameters and the heat transfer process. The effects of key parameters, temperature ratio and irreversible factors on optimal performance are investigated. The new model performance is compared with that of previous models. Results show that the new model provides a unified description for thermal Brownian refrigerators. The cooling load and COP exist maximal values about thermal conductance ratio between the two heat exchangers. When the thermal conductance ratio and other design parameters are optimal, the corresponding operating temperatures of the thermal Brownian refrigerator reach the optimal values. The results are universal, and it contains the results of previous models with different irreversible factors.