Optimal Ecological Performance of Three-Heat-Reservoir Thermal Brownian Heat Transformer
A finite-time thermodynamic model of three-heat-reservoir thermal Brownian heat trans-former with heat transfer loss is established,and the heat flow balance equations,heating load,coefficient of performance(COP)and ecological function are derived.The ecological performance characteristics of the cycle are studied by numerical calculation,and the advantages of ecological function as optimization objective are explained.The results show that external heat transfer can only reduce the cycle performance quantitatively,but not change the performance qualitatively.The system performance can be improved effectively by increasing the total thermal conductance of heat exchangers.The three-heat-reservoir thermal Brownian heat transformer can work under max-imal ecological function by adjusting the thermal conductance distributions and internal parameters properly.When the heat loading is substituted by ecological function as optimization objective,the heating load decreases less,but the corresponding COP increases more.