Numerical investigation of entraining performance and operational robustness of thermal vapor compressor having swirled motive steam inflow

Abstract

The importance of improving TVC's entraining ability in enhancing the efficiency of a multi-effect desalination (MED) system has been stressed for a long time. Moreover, the side effect detrimental to the system's operational stability when TVC is adopted for the MED plant has been frequently reported. In this study, an iterative CFD analysis was conducted to discover the TVC's shape that maximize its entraining performance, but we included a new design parameter of the motive flow's swirl intensity, which has never been previously considered as a TVC design parameter. Under the given reference operating pressures, the performance map was created in wide ranges of design parameters including the motive flow's swirl intensity. We tested whether the TVC will work in a stable double-choking range through an analysis of performance changing patterns for various operating conditions. Adopting the motive flow's swirl effect, a high entraining performance at reference condition as well as a good operational stability in wide operating ranges was achieved. This was impossible in the past when only the exteriorly geometrical parameters (like the mixing tube diameter and the primary nozzle exit diameter) were simply adjusted.