Two-phase radial ejector for transcritical CO₂ refrigeration.

This article focuses on the numerical investigation of a novel radial-flow ejector geometry designed for transcritical carbon dioxide (CO₂) refrigeration and air-conditioning (RAC) systems. Unlike traditional axial-flow ejectors, the radial ejector enables substantially higher mass flow rates—up to 16 times greater—while maintaining comparable entrainment ratios (ER) under similar pressure lifts, due to its larger motive throat area and reduced obstruction to the high-pressure motive flow. The study employs a homogeneous equilibrium model (HEM) with real-gas CO₂ properties to simulate two-phase transcritical flow, analyzing the effects of motive throat spacing, discharge pressure (compression ratio), and section lengths on ejector performance. Results indicate that an optimal motive throat spacing of 0.6 mm maximizes the operable range of compression ratios and mass flow rates, while the addition of a diffuser section enhances entrainment; overall, the radial ejector shows promise for compact, efficient designs in large-capacity CO₂ RAC applications.