Design And System Development Of A High Reliability Liquid Cooled Micropump

Under the background of rapid increase in heat flux density of electronic devices,heat dissipation has gradually become a focus for device and system design.Liquid cooling system has become a very promising cooling solution to replace air cooling system due to its high cooling capacity,low temperature range and compact structure.The reliability of micropump is still a bottleneck in applications where air cooling system has not yet been replaced by liquid cooling system on a large scale.Reference to the high reliability bearing design of heart pump in the field of biomedicine,micropump with the scheme of hydrodynamic suspension bearing for liquid cooling and contact ceramic bearing are designed in this paper.The design is validated experimentally and finally integrated into a highly reliable liquid cooling system.Firstly,the structure and principle of hydraulic suspension bearings for micropump are introduced.Radial hydrodynamic bearings and axial thrust bearings are designed and simulated.The calculated maximum pressure of the radial hydrodynamic bearing is121.24kPa,the bearing capacity is 12.56N,the maximum pressure of the axial thrust bearing is 43.89kPa,and the bearing capacity is 2.53N.The hydraulic components of a centrifugal micropump with flow rate of 2.63L/min,head of 108kPa and rotational speed of 20000rpm are designed by enlarged flow design and speed coefficient method.By the CFD simulation analysis of the micropump hydraulic components,the blade tip clearance leakage,the eddy current loss and the backwash disturbance at the volute tongue,the direct hydraulic flow loss caused by the vertical outlet pipe are the main hydraulic loss of the micropump.The simulation of the pump head is134.5kPa,efficiency is 52.8%.The hydraulic components of the micro-pump are processed and the prototype of the micropump is assembled.The flow-head curve of the micropump is measured at a speed of20000rpm.At the flow rate of 2.60L/min,the head is 109.2kPa,which meets the design requirements.The reliability test results of contact ceramic bearings show that alumina and silicon nitride ceramic materials have a good wear resistance performance;Zirconia bearings wear serious,are not suitable for underwater high-speed motor conditions.After running for340 days,the flow rate and head of the there pumps decreased by 25%,indicating that the wear resistance of alumina and silicon nitride is close underwater,which can meet the micropump continuous operation needs of about 1 years.A liquid cooling system with a micropump serving as cold plate is built.The structure of the micropump is modified so that the micropump can be in direct contact with the heat source to strengthen heat transfer by the intense turbulence inside the pump.The whole system structure is more compact.When the heat flux q is 83.8 W/cm~2,the heat source temperature T_h is 51.4°C.The experimental and numerical results show that the system has a good heat dissipation capability.