Compact, Low Temperature Refrigeration of Microprocessors

A compact, two-stage R-404A / R-508b cascade refrigeration system designed for interface with a high-performance microprocessor is under development. Such a system, designed to remove 100 W at –70 °C, can avoid the high cost of deep cryogenic cooling. Because thermal interface design is critical in maintaining low chip temperatures, a compact, microchannel evaporator is used. A chemically microetched copper interstage heat exchanger that uses branching flow paths for improved refrigerant distribution is under development. The initial temperature lifts, capacity, and physical size of the system are reported. Future work to refine the evaporator design and to further miniaturize the system through compressor design is planned. The ultimate goal is to build an inexpensive, quiet, reliable system, small enough for integration with a desktop computer, that can obtain a chip operating temperature of –70 °C.