Application of a valveless impedance pump in a liquid cooling system

In this paper, a novel valveless impedance pump is used, for the first time, in the thermal management of high-performance electronic systems. This small pump comprises an amber latex rubber tube, connected at both ends to rigid copper tubes of different acoustic impedance, and a simple, economic, quiet, and energy-efficient actuation mechanism, which combines a small dc motor and a cam. The motor-activated cam periodically compresses the elastic tube at a position asymmetric from the tube ends. Traveling waves emitted from the compression combine with reflected waves at the impedance-mismatched positions (rubber tube/copper tube interfaces). The resulting wave interference creates a pressure gradient, with the potential to generate a net flow. Several experimental setups for performance tests, using a single impedance pump, an open system with isothermal flow, and a closed liquid cooling system are designed and implemented. The performance of the impedance pump is affected significantly by the actuation frequency (input voltage) and position. The pump flow rate varies nonlinearly with the actuation frequency. The measured maximum flow rate of the current design is 480 ml/min at zero total pump head for operating frequencies in the range 48-63 Hz. The water-cooling system in a closed loop maintains the core temperature of the 60-W dummy heater at 57.8° C. Experimental results demonstrate the feasibility of the commercial application of valveless impedance pumps for thermal management in high-performance electronic systems.