Modelling and optimization of two-phase ejectors for cooling systems

A one-dimensional compressible flow model, which is based on the control volume approach, has been formulated to model and optimize one and two-phase ejectors in steady-state operation with particular reference to their deployment in a jet cooling system. The working fluid can be both single-component (NH3) and two-component (NH3–H2O). The developed model takes into account the duct effectiveness, wall friction, momentum loss, ejector geometry, shock waves as well as the acceleration of the induced flow in the conical part of the mixing section. Neither the usual assumption of mixing at constant pressure over the mixing chamber cross section nor that of a constant mixing chamber cross section were made. A comparison with other computation methods as well as with available experimental data from the literature is presented. The performance is significantly influenced by the ejector geometry.