Non-ideal effects assessment on organic vapor compressions using small radial turbocompressors for heat pump-based systems

Radial turbocompressor-driven heat pumps are currently being fostered for their application in a wide range of novel energy systems. This encourages the development of small centrifugal compressors that use different organic vapors. The present work aims to analyze the dynamical similitude preservation when a given heat pump operates with two different organic vapors (propane and isobutane). Scaling is carried out through an upgraded version of a previously developed similarity-based and generalized flow turbomachinery scaling methodology. Numerical calculations are conducted to quantify the non-ideal effects on key performance indicators. Furthermore, the use and of new dimensionless numbers are discussed, and their influence on scaling is assessed under the conditions of this study. The results show a good degree of agreement between the analytical predictions and the numerical simulation in terms of velocity flow field, polytropic efficiency and total pressure ratio. The findings of this work lead to set out that scaling with a proper non-ideal effects characterization is achieved without any further correction. Finally, this study confirms the suitability of the proposed similarity-based method for small radial turbocompressor-based heat pumps in the analyzed thermodynamic window design space. • An updated version of a generalized flow turbomachinery formulation is proposed using a dynamic similarity methodology. • Non-ideal flow behavior across a small radial turbocompressor under heat pump conditions using propane and isobutane is numerically analyzed. • Accurate predictions in polytropic efficiency and, specially, total-to-total pressure ratio (±1%) are obtained. • Dynamical similarity of a small radial turbocompressor working with two non-ideal fluids in the thermodynamic design window suited to heat pumps is proven.