Waste heat recovery in supercomputers and 3D integrated liquid cooled electronics

Ever increasing device density in electronic chips is beneficial for enhancing their computing efficiency. However, it also introduces severe challenges with respect to cooling solution which are indispensible for ensuring a reliable chip operation. Such steady miniaturization will soon render the traditional air cooling strategies futile and make the switching to liquid cooling inevitable. Superior thermal properties and ubiquitous availability make water the most suitable candidate as coolant. Building up on the reported studies in the literature, which have already established the feasibility of water as coolant, here we show that the superior thermal properties of water make it possible to cool electronic chips and data centers using hot water with inlet temperature up to 60°C. The concept is demonstrated through measurements on a copper made scalable manifold microchannel heat sink and a hot water cooled data center prototype. The high exergetic efficiency achieved using hot water cooling should make it possible to reuse the heat otherwise discarded in data centers and therefore improve the overall system efficiency and lower the carbon foot print of the data centers. Finally, the encouraging results are used to model water cooling of 3D chip stacks using an interlayer integrated cooling approach. The model results are compared with measurements on a model simulator and good agreement is found, which lays the ground work for realizing a model based optimization of integrated cooling structures for 3D chip stacks.