MEEM Graduate Seminar: Cooling of Embedded Electronics

Dr. Frank Kulacki, Professor of Mechanical Engineering at the University of Minnesota will be the ME-EM graduate seminar guest speaker for Thurs., Sept. 12 in 112 MEEM at 4:00 His presentation is entitled ‘Cooling of Embedded Electronics – Flow Boiling Is the Key to High Power Density’. He will also include the results of a survey of the ASME Heat Transfer Division.

Title: Cooling of Embedded Electronics – Flow Boiling Is the Key to High Power Density

The performance of embedded airborne electronics and computers is nearing a thermal limit. Devices and systems are now in development that will push heat transfer requirements to power densities greater than 1 KW/cm3 and average heat flux greater than 1 KW/cm2. Cooling techniques based on single phase forced convection cannot meet these requirements. The emergence of three-dimensional computing packages makes heat rejection even more challenging. This seminar reports measurements of heat transfer in flow boiling in short, symmetrically heated narrow gap channels. This geometry emulates the basic configuration of electronic devices envisioned in high power density embedded computing. Watt densities of 1 KW/m3 are considered, and it is demonstrated that sub-cooled flow boiling can achieve thermal regulation and maintain average temperatures below a 95 oC operating limit. Our measurements characterize heat transfer in a single pair of heaters and a set of three in line heat pairs. For the latter, uniform and non-uniform power density are addressed. Coolants investigated are water and NovecTM 7200 and 7300. Inlet Reynolds numbers range from 250 to 1200, Weber numbers from 2 to ~18, and boiling numbers from O(10-4) to O(10-3). Exit quality can reach 30 percent in some cases. Overall heat transfer coefficients of 40 kW/m2K are obtained. Pressure drops
for either experimental configuration are well within the capabilities of the airborne computer systems. Correlations for heat transfer are developed and generalized, and a systems analysis is suggested that will point toward a developmental path to externalized cooling approaches. At the conclusion of the technical presentation, some comments will be offered on the results of national survey conducted by the ASME Heat Transfer Division on the emergent trends in heat transfer engineering, research and education.

Dr. Frank Kulacki, Professor of Mechanical Engineering at the University of Minnesota, received his degrees in mechanical engineering at the Illinois Institute of Technology and the University of Minnesota. His research/interests include coupled heat and mass transfer in porous media, two-phase flow in micro-channels, natural convection heat transfer, heat transfer in metal foams, hybrid renewable energy systems, thermal energy storage technology, energy policy, management of technology, and the adaptation of computer-based technologies in engineering education. To date, he has 163 technical articles, 14 book chapters/review articles, 34 educational/professional articles, 28 technical reports, edited 7 books/conference volumes, two Springer monographs and has advised 20 doctoral, 43 masters, and 13 undergraduate research scholars. As the department chair at the University of Delaware, the dean of engineering at the Colorado State University and the dean of the Institute of Technology (now the College of Science and Engineering) at the University of Minnesota, he initiated and expanded computer-aided engineering and technology-based instructional activities, increased research funding, established new multidisciplinary degree programs, research initiatives, centers, and specialized research facilities. He chaired the Heat Transfer Division of the American Society of Mechanical Engineers, the ASME Task Force on Graduate Education, and the Education Advisory Group of the National Society for Professional Engineers. He served on the ASME Vision 2030 project which addressed the body of knowledge for mechanical engineers in the 21St Century, the ASME Board on Professional Development, the Board on Engineering Education, the Board of the Center for Education, the NSPE Task Force on Education and Registration, the DOE Peer Review Panel on Thermal and Hydrological Impacts of the Yucca Mountain Repository, and as the director of graduate studies for the MS in Management of Technology program at Minnesota. He has lectured on energy policy and related issues in the MOT program and at the Hubert H. Humphrey Institute for Public Affairs.

Dr. Kulacki’s advisory board experience includes the engineering programs at Swarthmore College, the University of Kentucky, the University of Maryland/Baltimore County, and Florida International University. From 1998 – 2001 he was an ASME Distinguished Lecturer. He has served as the Executive Director of the Technology-Based Engineering Education Consortium, an initiative of the William C. Norris Institute.

He is a Life Fellow of ASME and the American Association for the Advancement of Science (AAAS). At the University of Minnesota, he received the ASME Distinguished Service Award and the George Taylor Distinguished Service Award of the Institute of Technology.