Numerical Investigation of a Periodic Heating Thermal-Bubble Actuated Diffuser-Nozzle Valveless Pump

A valveless micropump actuated by thermal bubbles which generated by an electrode heater mounted with a pair of diffuser nozzles has been numerically studied by commercial CFD software FLUENT. The relationship between the net flow rate and the superheating and heat supplying frequency has been investigated. The depth of the diffuser-nozzle micropump used in current numerical simulation model is 200 mu m, and the diameter of micropump chamber is 1 mm. The pair of diffuser-nozzles are with gaps expanding from 30 to 274 mu m and open angles of 7A degrees. The working fluid is methanol in present study. The results show that the pump has different optimal driving frequency with different superheating. The cycle composed of bubble growth and shrinking costs more time at higher superheating. The maximum volume flow rate and the maximum pump pressure will increase with increasing superheating, simultaneously; and the optimal pulse duty, the maximum volume flow rate and pump pressure decrease with increasing superheating. The maximum volume flow rate and the maximum pump pressure are 29.6 mu L/min and 680 Pa at Delta T = 15A degrees C, respectively.