Researchers in the Cockrell School of Engineering at The University of Texas at Austin are developing the world’s first active heat pipe that can transport high heat loads over long distances. Unlike conventional heat pipes found in electronic devices and other tools, which can move heat over only a few inches, this new technology will be capable of transporting kilowatts of heat over distances of a meter or longer.
This discovery extends the use of heat pipes beyond small devices such as personal computers into larger-scale engineering applications, enabling more energy efficient, reliable and cost-effective cooling of data centers and power plants. By integrating this technology into existing infrastructure, data centers can eliminate the need for chilled air to cool the devices — which accounts for 1 percent of national electricity consumption, by some estimates. Other applications include spacecraft thermal control and and oil and gas drilling operations.
The performance breakthrough behind these patent-pending heat pipes, called electrowetting heat pipes (EHP), was conceptualized by mechanical engineering professor Vaibhav Bahadur (VB) and chemical engineering doctoral student Renee S. Hale. The researchers published their findings in the October issue of the journal IEEE Transactions on Components, Packaging and Manufacturing Technology.
Currently, desktop and laptop computers use traditional heat pipes to carry away heat generated by the processors, and to prevent overheating. Heat pipes rely on evaporation of a liquid at the hot end to absorb heat. At the cold end, the vapor is condensed, and the condensed liquid is pumped back passively to the hot end by a wick that lines the inside of the heat pipe. The pumping capacity of the wick limits the working length of the heat pipes; additionally, the performance is also dependent on orientation.
In contrast, the EHP is an “active” heat pipe and uses a microfluidic low power technology called electrowetting to pump liquid in place of the wick. This innovation eliminates the limitations associated with the wick and enables the development of low power, planar, compact heat pipes that can transport more than a kilowatt of heat over a cross section of only 10 centimeters by 4 millimeters.
“This technology will allow data centers to be cooled without actually chilling the air,” said Bahadur. “In a way, this allows ‘free cooling’ of data centers, since you don’t have to pay for electricity to chill the air, as is done presently; you use ambient air to cool the servers and telecommunications equipment, and then the hot air is discharged. This heat pipe can also enable more efficient cooling of power plants and reduce the water consumption for cooling.”
The UT Austin research team plans to continue progress on their discovery by further analyzing and prototyping this heat pipe in the coming months.
