New insights into the mechanism of fluid mixing in the micromixer based on alternating current electric heating with film heaters

Abstract

In order to solve the problem of difficult mixing of high-conductivity solutions, this paper designs a new mixing method of micromixer based on the alternating current (AC) heating effect. We set up the AC electrode and the film heater at the bottom of the microchannel. Under their joint action, the fluid in the microchannel will be affected by the Joule heat generated internally and the external heat source, so that the fluid disturbance and temperature distribution can be flexibly adjusted. It is characterized by joint numerical simulation. The key structural parameters of the micromixer, such as the electrode width ratio, the size of the film heater and the channel structure, are obtained to influence the performance of the micromixer. At the same time, the influence of the applied voltage amplitude and solution conductivity on the performance of the micromixer is analyzed. The results show that when only AC electrodes are applied, that is, the fluid in the microchannel is only affected by the Joule heat generated inside, the mixing efficiency of the micromixer can reach up to 83%. After we apply the film heater, that is, when in the combined action of an AC electrode and an external heat source, it is observed that the relatively high conductivity is as high as 0.2 S/m, and the mixing efficiency exceeds 90%. The two different fluids are almost completely mixed in the microchannel.