Investigation of the effects of the jet nozzle geometry and location on the performance of supersonic fluid ejectors

Abstract

Supersonic Ejectors (SE) can be used to replace mechanical compressors in several industrial applications, including residential and commercial space heating/cooling and water heating, industrial distillation/desalination and drying systems, among others. Since SE are thermally driven, the SE-based systems can make direct use of many forms of thermal energy including waste heat, solar thermal, natural gas, or biogas, depending on emission targets, availability and cost. In this paper, Computational Fluid Dynamics (CFD) has been used to investigate the effects of different geometrical parameters and operating conditions on the ejector performance. The numerical simulations were validated against experimental measurements in terms of entrainment ratio and pressure distribution. The effects of the supersonic nozzle location and its dimensions have been investigated with respect to pressure distribution. The flow dynamics was also investigated for various geometry parameters with the purpose of identifying the mechanisms leading to higher ejector performance. The main conclusion is that under a given set of operating regimes, different geometric parameters should be simultaneously considered for an optimal performance of a supersonic ejector.