Towards novel low temperature thermodynamic cycle: A critical review originated from organic Rankine cycle

As one of the most basic optimization factors of organic Rankine cycle, the working fluid greatly affects the development of organic Rankine cycle and even others low- and medium-temperature thermodynamic cycles. Towards novel thermodynamic cycle using low- and medium-grade energy, a critical review originated from the working fluid in organic Rankine cycle is presented. Three common-applied methods are presented firstly, namely trial method, analytical method and decoupling method. The recent progress of working fluid selection is classified, summarized and compared. Then, the dilemma of current research on thermodynamic cycle is critically analyzed and discussed, which could be summarized as three points: the restriction of limiting performance, the contradiction of working fluid selection and the misunderstanding on the application of zeotropic working fluid. What's more, the in-depth reason for the above issues from the traditional cycle structure is explored. Finally, from the viewpoints of fundamental research and linked methodology on novel thermodynamic cycle construction, several future development directions are put forward. The purpose of this paper is to summarize the research results, discuss the existing problems and provide suggestions for the future development. This review hopes to promote the development of novel thermodynamic cycle using low- and medium-grade energy.