Optimization design of steam ejector primary nozzle for MED-TVC desalination system

Abstract

The paper proposes a mathematical model and efficient optimization design method for ejector primary nozzle to deal with the coupled ejector configuration parameters. A primary nozzle of steam ejector for multi-effect distillation with thermal vapor compression (MED-TVC) desalination system based on the proposed method is devised and then the designed nozzle ejector performance is numerically investigated under various conditions. The performance results show that at fixed primary pressure, the entrainment ratio (ER) at critical mode and critical back pressure (CBP) increase almost linearly with the ascending secondary pressure and the individual linear regression empirical formula is attained, respectively. The normal shock position can serve as the indicator of the ER at critical mode and CBP. Altering the secondary or back pressure causes the axial movement of the normal shock wave within the ejector, changing the ejector performance. The proposed design method can improve the overall ejector efficiency by 14.41% compared with conventional methods.