This book presents a collection of key contributions from the fifth edition of the NICFD conference, organized by the ERCOFTAC Special Interest Group on Non-Ideal Compressible Fluid Dynamics (SIG-49). The book is intended to provide insight on the latest research findings in the field of NICFD that are relevant to a number of engineering applications related to the conversion of renewable and waste energy sources, like, e.g., organic Rankine cycles, super-critical CO2 cycle power plants, combustors operating with supercritical fluids, and heat-pumps. The various chapters of the book document research encompassing theoretical, computational, and experimental aspects of the gas-dynamics of non-ideal reactive and non-reactive flows and their impact for the design of internal-flow components (turbomachinery, heat exchangers, combustors). Since the accurate calculation of fluid thermo- physical properties is of great concern in NICFD, all the chapters address this problem by describing state-of-the-art models for the characterization of the properties of pure fluids and mixtures.