Ejector selection made easy: A new way of mapping performance of two-phase ejectors

Ejector as a work recovery device offers potential for developing energy efficient heating and cooling systems based on vapor compression technology. For many applications, the operating conditions vary significantly, leading to considerable performance degradation when system is operated in off-design conditions. Therefore, the system designing warrants development of accurate ejector performance models for wide range of operating conditions. In this paper, a novel methodology for ejector performance maps is proposed using the ejector efficiency as performance parameter and the volumetric entrainment ratio as characterizing parameter. The proposed performance map is developed after conducting experiments to find appropriate performance representation where ejector driven flow can be characterized using ejector motive flow. The developed performance map can predict ejector pressure lift within an accuracy of 20% using an iterative solver. In a later part of the paper, a system design study is conducted to select optimum ejector for a given compressor using proposed ejector performance maps.