Investigating hydrothermal mass transfer in an extremely low-pressure drop passive mixer: A three-dimensional simulation study

Abstract

Static mixers with low-pressure drops have been used for mixing in many biomedical and chemical applications. This study evaluates fluid flow with hydrothermal mass transfer in two types of vortex generators in a rectangular channel. The pressure drops in this new three-dimensional model were meager for Reynolds numbers of 50, 100, and 150. The extremely low-pressure drop passive mixer (ELPD) is a rectangular duct 400 mm in length and 20 × 20 mm in height and width. To improve the static mixer's thermal and mass transfer performance, five conical barriers and four longitudinal twisted tapes, sized at 3, 6, and 9 mm, were utilized, which were used as vortex generators. The vorticities and chaotic flow resulting from these vortices cause improved mixing by elongating and folding the fluid particles responsible for mixing in laminar flow. The simulation used water as the principal fluid and a red dye as a tracer. The results of this analysis are summarized in terms of a very low-pressure drop with a high mixing index for different heights and different Reynolds numbers. The study found that utilizing an ELPD with a bar height of 9 mm resulted in significantly enhanced mixing performance across the tested range of Reynolds numbers. This improvement was as high as 94%, and the associated pressure drop was the lowest among all tested configurations. Conversely, the research revealed that the 6 mm twisted tape height performed poorly in terms of both mixing improvement and heat transfer compared to the 3 mm and 9 mm heights. Considering these findings, utilizing an ELPD with a 9 mm bar height is recommended for optimal mixing performance.