Enhancement of Entraining Performance on Thermal Vapor Compressor for Multi-Effect Desalination Plants by Swirl Effects of Motive Steam

Abstract

Efficiency of a multi-effect desalination (MED) system with a thermal vapor compressor (TVC) is highly affected by the entraining performance of TVC. TVC's high entraining ability makes it possible to reduce the heat transfer area in evaporators or keep the top brine temperature (first effect cell-side temperature) lower. Therefore, to achieve a higher entrainment ratio of TVC, we investigate the cases in which the motive steam flows into the primary nozzle with a swirl component. The compressible, axisymmetric, and swirled flow is numerically solved for various swirl-to-axial component ratios. The Mach number, isobars, radial velocities, and shock patterns are compared to evaluate the effect of the swirled motive steam inflow on the entrainment ratio. This numerical study revealed that there exists an optimum swirl angle that maximizes the entrainment ratio.