SEM Image of Alumina Nanoparticles Courtesy of Olin College of Engineering

Research continues for ways to improve the performance of cold plates and heat exchangers to handle increasingly high heat load densities for electronics cooling. Dr. Jessica Townsend, assistant professor of mechanical engineering at the Franklin W. Olin College of Engineering, recently published a paper on nanofluids with her colleague Dr. Rebecca J. Christianson, assistant professor of applied physics. The paper, “Nanofluid Properties and Their Effects on Convective Heat Transfer in an Electronics Cooling Application,” shows some very promising results in the use of nanofluids for liquid cooling.

The findings of Dr. Townsend’s and Dr. Christianson’s research included up to an additional 8°C reduction in chip temperature when a 1% volume fraction of alumina-in-water nanofluid was used as the coolant in a liquid cooling loop in place of deionized water. Alumina-in-water at a 2% and 5% volume fraction was also investigated but resulted in a much smaller decrease in junction temperature.

Dr. Townsend and Dr. Christianson are planning future experimental studies to look at whether nanofluid thermal conductivity increases anomalously with temperature and whether nanoparticle size is a factor. This could result in the potential to “tune” nanofluids for more effective performance at particular temperature ranges.

Townsend, J, Christianson, R. J., 2009, “Nanofluid Properties and Their Effects on Convective Heat Transfer in an Electronics Cooling Application,” Journal of Thermal Science and Engineering Applications, Transactions of the ASME, Vol. 1 / 031006-1.

Faulkner, D. J., Rector, D. R., Davidson, J. J., Shekarriz, R., 2004, “Enhanced Heat Transfer Through the Use of Nanofluids in Forced Convection,” Proceedings of the 2004 ASME International Mechanical Engineering Congress and Exposition, pp. 219-224.

Lee, J., Mudawar, I., 2007, “Assessment of the Effectiveness of Nanofluids for Single-Phase and Two-Phase Heat Transfer in Micro-Channels,” International Journal of Heat and Mass Transfer, 50(3-4), pp. 452-463.

Chein, R., Chuang, J., 2007, “Experimental Microchannel Heat Sink Performance Studies Using Nanofluids,” International Journal of Thermal Sciences, 46(1), pp. 57-66.

Valencia, G. E., Ramos, M. A., Bula, A. J., 2007, “Experimental Evaluation of the Convective Heat Transfer Coefficients in a Nanofluid-Cooled Milli Channels Heat Sink,” Proceedings of the 2007 ASME International Mechanical Engineering Congress and Exposition, pp. 31-37.

Heat Exchanger ES Series

Lytron frequently receives questions through its “Ask an Engineer” website form. A customer recently asked us the following question: “We’re planning on using one of your flat tube heat exchangers for radar cooling. What is the MTBF for your ES Series heat exchangers?” 

CP10 Cold Plate

Lytron frequently receives questions through its “Ask an Engineer” website form. A customer recently asked us the following question: “Will the CP10 cold plates work in a vacuum? Will thermal contact between the tubing and plate be maintained in a vacuum?”
 
There would be a minor impact to the performance of the CP10 cold plate if it was used in a hard vacuum. Lytron does not use epoxies between the cold plate’s tube and plate, which results in lower thermal resistance under standard conditions as compared to cold plates that do have epoxy. Experiments have shown that the tube installation process yields very good contact between the cold plate’s tube and plate. However, small air gaps do exist. If a CP10 cold plate is exposed to a high vacuum environment this air will escape and increase thermal resistance. While we haven’t done any CP10 cold plate experiments in a vacuum, I’d estimate a 10%-20% increase in thermal resistance.