Abstract
We have developed a high flow rate stable liquid dispensing system by using a low energy consumption actuator. It is made of a piezoelectric (PZT) actuating porous membrane with the resonant frequency of the system, featuring relatively small movement parts with a robust structure. Taking advantage of the high latent heat during phase changes from water droplet to vapor, we were able to remove heat from a hot body surface of over 100W with the dispensing system as cooling application. The cooling system had the following advantages. First, it is operated under environmental pressure, so its coolant does not leak as the system fails. Second, the stability of the cooling system could be maintained by controllable flow rate because the dispensing flow rate is not dependent on the backpressure of the water tank. Third, the PZT actuator structure containing the pump and dispenser is simple and easy to manufacture. Finally, the optimized operating conditions are identifiable for the high flow rate pumping system to operate with low noise and power. However, the condensed water on the orifice will lead to dispensing failure with the puddling problem. A local anti-wetting trench of nozzle plate is provided in this paper. The nozzle plate includes orifices and trenches structure with some filler. The wetting angle of the surface of the filler is different from the wetting angle of the surface of the nozzle plate. Since the surface of the nozzle plate has a specific property, e.g., a wettable property or an anti-wetting property, the water or solution passing through the orifice is not easily retained or puddling on the nozzle plate. Thus, the stability of the dispensing system could be controlled as the puddling probability reduced. ©2009 IEEE.