A novel micropump for integrated microchannel cooling systems
Abstract
The objective of this work is to develop a micropump for integrated microchannel cooling systems. The severe pumping requirements of microchannel heat sinks and limited space availability have necessitated the development of compact pumping technologies. A comprehensive review of the state of the art in microscale pumping technologies was conducted. The pumping technologies were evaluated to assess their suitability for microchannel heat sinks. The pumping requirements of the microchannel heat sinks were studied and a graphical method to assess the suitability of pumping techniques to microchannel heat sinks was developed. Further, microchannel dimensions were optimized for minimum pumping requirements. Based on these studies, a novel micropump design especially suited for electronics cooling applications and capable of integration into microchannel heat sinks was proposed. The micropump is based on concepts of valveless nozzle-diffuser micropumping and induction electrohydrodynamics (EHD). A transient, three-dimensional model of the pump capable of solving coupled charge transport and Navier-Stokes equations was developed. The model was used to study the performance of the pump and analyze the effects of various parameters. Results from the model indicated variation in output power from EHD due to variation in the instantaneous bulk fluid velocity. A detailed investigation of the effect of instantaneous bulk fluid velocity on the efficiency of conversion of electrical power into fluidic power in EHD pumping devices was conducted. Steady-state and transient ion-drag pumps and attraction- and repulsion-type induction EHD pumps were considered. The results of this study prompted changes in the design of the micropump to exploit the increased efficiency of EHD at high instantaneous bulk fluid velocities. This design was studied numerically and the flow rate achievable from the pump was predicted. A micropump based on repulsion-type induction EHD was fabricated using silicon micromachining techniques. The micropump was tested and the resulting fluid velocities were determined using microscale particle image velocimetry. The experimental fluid velocities agreed with the predicted values to within 30%. The flow rate and heat transfer rate achievable from integration of pumps in microchannels and power input required is estimated.
Degree
Ph.D.
Advisors
Garimella, Purdue University.
Subject Area
Mechanical engineering|Electrical engineering
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