传热对热布朗热泵性能的影响

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

本文建立了热布朗热泵的有限时间热力学模型.假设热源与黏性介质间服从牛顿传热规律,导出了供热率和供热系数的解析式.分析了传热对布朗热泵性能的影响,给出了布朗热泵的有效工作区域,并与宏观内可逆卡诺热泵的性能进行了比较.在总热导率一定的约束下,通过优化热导率分配得到了系统的最大供热率.结果显示新模型的供热率比非平衡热力学模型的供热率更小,且更接近实际.增强热源与黏性介质间的传热可以有效提升系统的性能.供热率关于热导率分配比存在极值,供热系数不受热导率的影响.当总热导率无穷大时,模型变为非平衡热力学模型.缩小热源间的温差可提高供热率,供热系数与热源温度无关.

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 heatexchanger 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.