Recent progress in experimental studies of Organic Rankine Cycle

Energy shortages and environmental pollution problems are crises in the development of humanity. The utilisation of sustainable energy is an effective solution to relief the crises. As a promising technology, Organic Rankine Cycle (ORC) can convert sustainable energy, such as solar energy, geothermal energy, biomass energy and waste heat, in to electrical and mechanical energy. The ORC system has the same system configurations as steam Rankine cycle but uses organic working fluids with low boiling points and has the characteristics of a simple structure, high stability, wide suitability and easy construction. In the past few decades, a large amount of research on the ORC has been carried out including the selection of working fluids, the design and manufacture of expanders, the optimisation of whole system and the dynamic simulation and control of ORC system. In terms of methodology, these studies can be divided into three categories, namely the theoretical analysis, the software simulation and the experimental study. An overview of the experimental studies of ORC system is presented in this paper; the methodology of the research is introduced including data collection, data arrangement and data analysis. The results of comparisons between existing experimental studies using thermodynamic perfectiveness and the analysis of various types of expander are then presented. Lastly, based on the analysis of experimental studies of small-scale ORC systems, the key problems existing in the current ORC and the development trend of ORC systems are discussed to provide some references for a wide range of uses of the ORC system.