The design and experiment research on two-phase flow dispenser

A novel approach of non-contact fluid dispensing has been proposed based on the principle of gas-liquid two-phase flow. For the direct driving principle, the slug flow pattern can be obtained stably in the micro-channel as the flip ratio between the liquid and gas is in an appropriate range. The slug flow has a special characteristic that is the liquid droplets have been separated by the air bubbles uniformly and stably. This can be used to execute a precise liquid dispensing by slug flow control. This paper applied the two-phase flow principle for adhesive dispensing. The continuous air was introduced into the continuous liquid to form a gas-liquid two-phase slug flow in the mixing chamber. As a result, the continuous liquid was cut by the bubbles to be uniform and constant droplets and spray out of the nozzle. The droplets on the substrate have uniform interval, accurate volume, good consistency, high controllability and no back haul. The experiment results supported that the process parameters had strong linear relationships with the geometrical dimensions. This is a very important truth that the independent variables, Φ_nozzle, Φ_needle, Q_gas, Q_liquid, and D_distance, can control dependent variables of f_droplet and M_droplet to realize high precision dispensing.