Effect of heat transfer on the performance of thermal Brownian heat pump

Abstract

<p indent="0mm">A finite-time thermodynamic model of the thermal Brownian heat pump is established in this paper. The heat transfer between a reservoir and viscous medium is assumed to obey Newton’s law. The expressions for the heating load and coefficient of performance (COP) are derived. The effects of heat transfer on thermal Brownian heat pump performance are analyzed, and the valid working region of a thermal Brownian heat pump is obtained. The performance characteristics of the Brownian heat pump are compared with those of the macro endoreversible Carnot heat pump. For a fixed total heat-exchanger inventory, the distribution of heat-exchanger inventory is optimized for maximizing the heating load. The results indicate that the new model with thermal resistance delivers less heating load than the nonequilibrium thermodynamic model, and the new performance characteristics are closer to reality. The system performance can be improved by enhancing the heat transfer between the reservoir and the heat pump. An optimal heat-exchanger inventory ratio exists for maximizing the heating load, and the COP is irrelevant to the heat-exchanger inventory. When the total heat-exchanger inventory is infinite, the model becomes a nonequilibrium thermodynamic one. The heating load can be improved by reducing the reservoir temperature difference, and the COP is not affected by the reservoir temperatures.