Micro-Innovation

Mechanical engineers at Purdue University have created a miniature device that aims to replace conventional evaporators. Cited as a "long-term solution" in technological advances, the use of existing technical know-how for the refrigeration loop combined with new know-how has led to the creation of a micro-channel heat sink, a copper plate containing numerous grooves 231 microns wide, i.e. approximately three times the width of human hair, and 713 microns deep. The intricate coil system of conventional evaporators removes heat from the refrigerator as the coolant circulates through the tubing and is often well over 1 m long. The heat sink is only one-inch square. A miniature device such as this would keep electronic components cooler than conventional cooling apparatuses, enabling improved performance and faster operation times. However, new systems need to be designed for micro-channels as fluids flow differently than in larger tubing and bubbles form differently, affecting heat dissipation. An advantage in innovating conventional refrigeration systems is that most of the technology is already available. For example, the problem of intense increasing and decreasing pressure oscillations along the parallel channels of a micro-channel was almost completely eliminated by the throttling valves used in refrigerating systems. Attached to a heating element that stimulated a hot electronic component, the heat sink has been tested with R-134a at Purdue. The combining of the cooling elements of a two-phase micro-channel heat sink with the low-temperature capability of a standard refrigeration system results in a high-performance cooling system capable of removing large amounts of heat whilst maintaining low chip temperatures, not currently attainable by any competing cooling technology.