关键词: 低耗散热机/
热转移律/
权衡判据/
热机效率
English Abstract
Trade-off optimization for low-dissipation heat engine with generic heat transfer process
Lu Can-Can,Bai Long
1.School of Physics, China University of Mining and Technology, Xuzhou 221116, China
Fund Project:Project supported by the Fundamental Research Funds for the Central Universities (Grant No. 2015XKMS082).Received Date:17 August 2016
Accepted Date:27 September 2016
Published Online:05 February 2017
Abstract:The heat transfer process inevitably occurs in the operation of real heat engine. In this article, a low-dissipation heat engine with generic heat transfer process is proposed based on the low-dissipation Carnot model. The formulas for the power and the efficiency of heat engine with generic heat transfer law are derived, and the low-dissipation heat engine performance is also optimized by the trade-off optimization method, which offers a unified scheme to understand the behaviors of heat engines with generic heat transfer processes. Furthermore, the characteristics of the power as well as the efficiencies for thermal engines with the different heat transfer processes are discussed in detail, and it is found that the power and the efficiency without heat transfer process are independent of heat leak, but are related to contact time, heat dissipation and Carnot efficiency. The power output of heat engine monotonically increases as Carnot efficiency increases, but the large contact time ratio and the large dissipation ratio make it difficult to provide the big power output. When the heat leak is absent and () is fixed, the efficiency of heat engine decreases (increases) with the increase of (). It is noted that the heat transfer process greatly influences the performance of heat engine, and /C versus displays the similar properties under three heat transfer laws. It is clearly shown that /C versus shows the transition from the monotonic decrease to monotonic increase with increasing, but /C versus is opposite to the former, and the maximum value of /C also shifts rightwards with the increase of . Additionally, the corresponding efficiency of heat engine diminishes significantly as m decreases and n increases. When heat engines are dominated by different heat transfer laws, the curves of versus C are consistent as C is relatively large or small, but it is observed that there exist the evident differences among three characteristic curves in the middle regime. The relatively large or small will also lead to the reduction of the working regime where heat engine can function normally. Our results are very helpful in understanding the design principle and the optimization mechanism for actual thermal engines and refrigerators.
Keywords: low-dissipation heat engines/
heat transfer laws/
trade-off criterion/
efficiency of the heat engine
