How to approach Carnot cycle via zeotropic working fluid: Research methodology and case study

Zeotropic mixture, which commonly consists of two or more pure working fluids, has flexibility in thermos-physical properties with a possible potential to enhance the cycle performance. The effects of thermos-physical properties of zeotropic mixture should be considered when determining the cycle structure and the design of components. This paper presents a novel construction method of thermodynamic cycle based on the zeotropic mixture. By adding the thermodynamic coordinate of working fluid, a 3D cycle diagram based on the traditional temperature and entropy cycle diagram is applied for performance analysis of cycle. According the proposed construction method, a baseline cycle, composed by ORC sub-system and compositions regulating sub-system, is put forward and available compositions regulating techniques for such cycle are discussed as well. Finally, a representative case is described briefly and the features are summarized. This work provides a new methodology view to guide researchers in energy-efficient design of thermodynamic cycles.