Microfluidic Cooling Channels On the CPU : RIT: "Dr. Satish G. Kandlikar, Gleason Professor of Mechanical Engineering at RIT, received an IBM Faculty Award for the second consecutive year to conduct research on liquid cooling of next-generation computer chips. To achieve this, microchannels are etched directly on the back side of the computer chip and water is circulated to carry the heat away. This fundamental research is aimed at increasing the cooling rate from around 50 Watts/cm2 to well over 500 W/cm2. The chips are fabricated by IBM at their T. J. Watson research center. This work has been conducted at the Thermal Analysis and Microfluidics Laboratory at RIT by Mark Steinke, who successfully defended his doctoral thesis in microsystems engineering this past academic year. Future work in this area will focus on utilizing boiling in these chips. "

Purdue University Microchannel Cooling System: "At Purdue University, Mudawar and doctoral student Jaeson Lee have already demonstrated the potential of their microchannel heat sinks. “We really have a working system now,” said Mudawar, whose study is funded by the U.S. Office of Naval Research. Mudawar and Lee were able to successfully use a one-inch square copper microchannel plate to serve the same evaporative cooling function as the one-meter long tubing used in a refrigerator. “The issue now is going to be packaging the cooling system around the device." "Developed by researchers at Purdue University, this copper microchannel heat sink contains numerous grooves each 231 microns wide — about three times as wide as a human hair — and 713 microns deep." " By modifying conventional refrigeration technology with the tiny devices, they could be used to cool space, military and computer systems."

Soliton R&D Corp Kapton Polymide Ribbon Capillary CPU Liquid Cooling : Nikkei Electronics Asia reports on a Kapton Polymide ribbon capillary CPU liquid cooling system by Soliton R&D Corp of Japan. ; "A new type of water-cooling technology has appeared to handle IC heating issues in PCs and other equipment. Compared to existing water-cooling modules it seems to offer better heat radiation performance, smaller and lighter specs, and cheaper manufacturing. The new technology is under development by Soliton R&D Corp of Japan, a technology start-up involved in R&D of flexible circuit boards. The basic approach is to form an extremely fine network of channels through Cu foil, passing the water or other cooling medium. Eventually the firm hopes to form it as an integral part of the printed circuit board (PCB) or flexible circuit. The firm commented that the prototype is already capable of cooling the surface temperature of a 150W IC low enough for normal operation. One of the reasons that Soliton's design achieves such high cooling performance is that it uses fine pipes - or capillaries. The total surface area can be maximized in comparison to the coolant volume, boosting performance. For example, the A4-size Cu sheet used as the radiator has a large number of capillaries running parallel, with a length of over 3 meters each for a total path length of 30 meters. The capillaries are 1.5mm in width, and 150µm deep. Both dimensions were based on the performance of the existing pump, and will be reduced to about 50µm square in future designs. These numbers are on a par with the "microchannel" design under development by Intel and others for microprocessor cooling. A smaller capillary cross-section means that the Cu sheet can be made thinner, which is the key to smaller and lighter modules. The Cu sheet used in the prototype was 0.4mm thick, but Soliton expects to be able to reduce this to 70µm. At 0.4mm, the A4-size Cu sheet weighs over 200g, but this would be reduced to under 40g if only 70µm thick."

Spray Cooling with Isothermal Systems Research : Isothermal Systems Research (ISR) have developed a CPU cooling technology called Spraycool, which replaces traditional heatsinks with a rather novel form of liquid cooling that utilizes jets of atomized fluid sprayed onto a cold plate in a fully enclosed environment. The SprayCool Technology has being designed for use with High Performance Servers in racked configurations, in the above example, wherein the liquid cooling system removes the heat from the rack and centrally cools it, thereby decreasing overall energy costs. The server rack system by ISR operates with 3M Fluorinert and consists of a SprayModule, Fluid I/O, and 3U Thermal Management Unit. The fundamentals of the technology are outlined in greater detail in the mfgr's whitepaper, and apparently capable of handling a heat flux from 100W/cm2 to 2000 w/cm2. Essentially though, the apparatus operates under the following principles; "A non-conductive and non-corrosive coolant is atomized and sprayed directly onto electronics to provide cooling. The coolant vaporizes and heat is rejected to the enclosure and/or through a heat exchanger, condensing the vapor back into a liquid state. The process continuously cycles within a closed loop sealed enclosure that prevents corrosive environmental contamination from harming sensitive electronics." Another research paper from the University of Wisconsin-Madison offers better insight into the construction and engineering behind a spray cooling module.