Shusheng Zhang

Comparative analysis of mixing performance and pressure loss of three types of passive micromixers

Effective mixing of microfluids is the basic requirement for biochemical analysis. The alteration of internal structure and shape of microchannel can increase the interfacial surface areas and then improve the mixing performance. Three types of micromixers with different structures were investigated with numerical simulation. Meanwhile, the mixing performance of 3 types of passive micromixers was compared. Consequently, the pressure loss of the micromixers was studied. The results shows that the mixing performance of the internal-rib micromixers surpasses the other two types of micromixers under 5 different inlet velocity conditions. The pressure loss of the micromixer gradually increases with the flux growth. The pressure loss of internal-rib micromixer is the largest, Z-shaped micromixer takes the second places and Y-shaped micromixer is the least. In particular, when Q is 288mLh-1, the pressure loss of micromixer is large, which is not conducive to the integration of microfluidic chips. However, When Q = 28.8mLh−1, the internal-rib micromixer with a high mixing efficiency and low pressure loss is able to meet the requirement of microfluidic chips.

Notice of Retraction Study on bubble dynamics of boiling in vertical rectangular mini-channel

Boiling heat transfer in vertical rectangular mini-channels with a width of 2 mm and a length of 390 mm is studied in this paper. The courses of bubbles generation, growth and departure were numerically simulated, the influence of the wall overheating and the movement of bubble bottom micro-layer is analyzed and compared with the experimental datum. All the calculation conducted takes the gravity, surface tension and wall adhesion into account. It is found that surface tension is much more important than gravity in the process of boiling heat transfer. As the overheating is increased, the departure diameter D of bubbles increases significantly. When the bubble diameter D is larger than 1.5 mm, it will be influenced by the incoming flow. The existence of bubble bottom micro-layer accelerates the flow convection on the wall and increases the coefficient of heat transfer. The results of simulation have a good coherence with experimental datum.

Research of Flow Boiling Bubble Dynamics in Vertical Rectangular Mini-channel

Flow boiling in vertical rectangular mini-channel with width of 2mm and length of 390mm is studied in this paper. In single-side heating situation, the narrow channel is divided into three zones, bubbles generating zone, growth zone and annihilation zone. The motion characteristics of bubbles in various stages are accompanied by the changes of three zones. The courses of bubbles generation, growth and departure are numerically simulated. All the calculation conducted takes the gravity, surface tension and wall adhesion into account. Found that surface tension is much more important than gravity in the process of boiling heat transfer. As the overheating increases, the departure diameter D of bubbles increases significantly. When the bubble diameter D is larger than 1.5mm, it will be influenced by the incoming flow. The existence of bubble bottom micro-layer accelerates the flow convection on the wall and increases the coefficient of heat transfer. The results of simulation have a good coherence with experimental datum.