بهینهسازی هندسی اجکتور فراصوتی برای بهبود عملکرد آن در سیستمهای تبرید

Abstract

Due to an increasing need for refrigeration systems and their growing electrical demand and greenhouse gases production, using ejector refrigeration systems would be a suitable substitution for conventional cooling systems. Main drawback of ejector refrigeration systems is their low coefficient of performance. The key component to improve the cycle performance is the ejector. Prerequisite of improving ejector performance is an accurate computational fluid dynamics simulation for predicting its entrainment ratio. In this study, a two dimensional, axisymmetric, steady state, compressible flow computational fluid dynamics simulation of a supersonic ejector is performed. In the second part of this study, geometrical optimization of the simulated ejector for two different objective functions is performed. The first objective function considered was the ejector entrainment ratio. The optimization with this objective function led to 53% relative improvement in the entrainment ratio with a negligible decrease in critical pressure. The second, objective function considered was the exergy efficiency in which the optimization showed 39.6% relative improvement. The exergy efficiency is used for the first time in the literature as the objective function for optimization of ejector geometry.