Long Rui, Liu Wei
School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Apr;91(4):042127. doi: 10.1103/PhysRevE.91.042127. Epub 2015 Apr 22.
An analysis of the efficiency and coefficient of performance (COP) for general heat engines and refrigerators with nonisothermal processes is conducted under the trade-off criterion. The specific heat of the working medium has significant impacts on the optimal configurations of heat devices. For cycles with constant specific heat, the bounds of the efficiency and COP are found to be the same as those obtained through the endoreversible Carnot ones. However, they are independent of the cycle time durations. For cycles with nonconstant specific heat, whose dimensionless contact time approaches infinity, the general alternative upper and lower bounds of the efficiency and COP under the trade-off criteria have been proposed under the asymmetric limits. Furthermore, when the dimensionless contact time approaches zero, the endoreversible Carnot model is recovered. In addition, the efficiency and COP bounds of different kinds of actual heat engines and refrigerators have also been analyzed. This paper may provide practical insight for designing and operating actual heat engines and refrigerators.
在权衡准则下，对具有非等温过程的通用热机和制冷机的效率和性能系数（COP）进行了分析。工作介质的比热容对热设备的最优配置有显著影响。对于定比热容的循环，发现效率和COP的界限与通过内可逆卡诺循环得到的界限相同。然而，它们与循环持续时间无关。对于无量纲接触时间趋于无穷大的变比热容循环，在非对称极限下提出了权衡准则下效率和COP的一般交替上下界。此外，当无量纲接触时间趋于零时，恢复到内可逆卡诺模型。此外，还分析了不同类型实际热机和制冷机的效率和COP界限。本文可为实际热机和制冷机的设计与运行提供实际见解。
