A novel planar module design for improved direct contact membrane distillation: Experimental and computational fluid dynamics insights

• Novel DCMD design boosts flux by 84% vs. conventional modules. • CFD confirms dead zones reduce traditional designs’ performance. • New design achieves 35 kg/m²·hr flux at 70°C feed temperature. • Spacers cut performance gap to 28%, due to enhancing turbulence. • Optimized flow dynamics drive gains, not temperature differences. Despite the simplicity of direct contact membrane distillation (DCMD) systems, their performance has not yet met high expectations. While significant research has been conducted at the lab scale to enhance DCMD efficiency, the effects of entry and exit flow have largely been overlooked. This study introduces a novel DCMD cell design, which was experimentally tested and compared to the traditional design commonly used in membrane research. Both designs were evaluated under identical conditions, including flow velocity, feed and permeate inlet temperatures, membrane cell dimensions, and the effective membrane surface area. The experimental results demonstrated that the proposed topology outperformed the traditional one by 47% - 84%, considering the operating conditions. Additionally, when net spacers were used, the performance difference between the two designs decreased to 17% - 32% depending on the operating temperature condition, with the new design consistently showing higher productivity. To further explore these differences, the CFD analysis revealed that dead and wake zones in conventional design were key factors contributing to low flux, while the proposed design exhibited improved heat convection, resulting in higher thermal performance and overall system efficiency.