A mechanical micropump for electronic cooling

Recently, active cooling system is strongly needed in high heat flux density microelectronics. Micropump is the essential component in the active cooling system. In this paper, a mechanical micropump is proposed for electronic cooling with a 2L/min flow rate, 90KPa pressure head at 22000 rpm (revolutions per minute). The overall size of the micropump prototype is 43mm in width and 65mm in length. To investigate the impeller performance in minisize, both closed impeller and open impeller were designed. Experiments were conducted at 4 different rotational speeds to characterize the micropump models. Then, flow field simulation was implemented based on computational fluid dynamics (CFD) to compare the hydraulic properties and analyze the influence of the impeller clearance. According to the experimental results, the micropump with close impeller generated 89.3KPa pressure head at nominal condition and the one with open impeller generated 91.2KPa, both of which approached to the nominal design point. Differing from expectation, the overall efficiency of the close impeller model was only 26.2%, a little higher than the open impeller of 22.8%. From the CFD analysis, flow separation and vortexes were significant in open impeller passages which are the main causes of the low efficiency performance. The leakage and disc friction accounted for a large proportion in the closed impeller overall power loss. Despite of prominent flow performance, the closed impeller does not present significant advantages than the open impeller in minisize.