Theoretical and experimental investigations of different area ratios of a supersonic ejector driven by compressed air

Abstract

Ejectors have some advantages such as being simple, reliable and no moving parts. They can be used in air-conditioning and refrigeration applications. This paper presents a comparison of ejector performance, primary pressure (Pp), back pressure (Pb) and area ratios of ejectors (A2/At) predictions by an analytical model and a computational fluid dynamics model for different operating conditions. Six different area ratios of ejector using air as working fluid in this study were proposed and tested experimentally. The variable area ratios of ejectors (A2/At) were used with a range from 10.68 to 30.62. Two sets of ejectors (A and C) are studied and examined depend on the kind of nozzle. The aim of this study was to investigate these ejectors under variation of primary pressure (Pp) (1.5-6.0 bar) and adjustable spindle position (0 to -25 mm). Two groups of ejectors (A and C) were categorized based on the type of nozzle. The experimental results validate the solutions of the main parameters of ejectors using air as working fluid. The results show that group A is more appropriate for higher values of back pressure, while group C is more suitable for high performance of the ejector. Finally, the main parameters were carried out on six different ejectors to find the best combination based on various nozzles and constant area sections.