A novel steam ejector with pressure regulation to dredge the blocked entrained flow for performance improvement in MED-TVC desalination system

Steam ejectors are regarded as a promising energy-saving technology, it is thus crucial to enhance its working performance for broader application horizons. In this study, a detailed simulation is made of a design steam ejector used in MED-TVC desalination system. The results discloses that there is actually a large entrained flow blocked region downstream the entraining entrance and significant low-pressure potentials inside the throat and diffuser whose pressure are far lower than that of the blocked region. Based on this finding, a so-called pressure regulation technology is proposed to use these existing pressure differences to dredge the blocked entrained flow, and thus more entrained steam could be drawn into the ejector. Then the feasibility verifications of different pressure regulation schemes are carried out, and a systematic analysis and investigation of their influences on the entrainment performance has been implemented systematically from the mass flow rate and pressure field. The results reveal that there is an optimum combination of pressure regulation schemes to dredge the blocked entrained flow effectively, by which a maximum and considerable entrainment ratio improvement could be achieved, as large as 26.85% in the covered simulations, and with 3.31% even under the design condition. To be specific, the throat-entraining entrance downstream pressure regulation should be adopted if the ejector operates under the design condition, otherwise, the combined-entraining entrance downstream pressure regulation is the best choice.