Application of Computational Fluid Dynamics to the Optimization of Heat and Momentum Transfer in an Industrial Air Blast-Freezing Tunnel

Serpentine micromixers are simple in design, have a high mixing performance, and thus are preferable among passive micromixers. Conventional geometries such as square-wave, circular, and zigzag have widely been investigated by researchers. High-pressure loss diminishes the cost-effectiveness of micromixers. To mitigate the pressure loss and maintain high mixing efficiency, a novel 3D square-wave serpentine micromixer with misaligned inflow is introduced. The design integrates the concept of nonaligned inlets and a highly effective square-wave cross section inside a serpentine micromixer. Flow analysis was done for Reynolds numbers 5 to 50 and a mixing efficiency above 90% was achieved. The design amalgamates two square-wave cross section with lateral misalignments thereby producing a vortex flow at each mixing junction (chamber). The results suggest strong vortex mixing along with cross-flow phenomenon (vortex propagation and intensification) inside the mixing chamber. The core vortex region was also analyzed. For Reynolds number 30, a mixing index of 0.92 is observed with pressure loss around 5 kPa and a mixing length of 3.7 mm. The effect of the average temperature and temperature gradient of fluid is also discussed. A detailed comparative study is also established, which successfully demonstrates the edge of the proposed design.