Development of an embedded vapor-compression refrigeration system for computer CPU cooling

As frequency and power dissipation of microprocessor have been constantly increasing, the traditional cooling methods such as heat sink, fan and heat pipe are getting harder and harder to meet the cooling demand of new generations of high power CPUs. Using vapor-compression refrigeration to cool high heat flux CPU is considered to be one of the most promising techniques for it has the advantages of high efficiency, high power density, and being able to keep the CPU below ambient temperature. In this paper a novel vapor-compression refrigeration system for computer high heat flux CPU cooling has been developed and tested. The refrigeration system is so small that it can be embedded into the computer case. The refrigerant of the system is R-134a. The system consists of a miniature rotary DC compressor, a microchannel condenser, a specially designed cold plate, a short tube (throttling component), and related controlling electronics. The compressor is powered directly by the 12V DC power supply of the computer. The cold plate contacts the CPU surface via a buckle and carries away the heat dissipation by conductivity. In a series of tests to cool an Intel Core i7-990X CPU that has 12 cores inside with the refrigeration system, the CPU core temperature can be kept at 23°C in default frequency 3.5GHz and 100% of workload. When the CPU is overclocked to 4.8GHz, the core temperature can be maintained at 59°C. Even when overclocked to 5.0GHz, the core temperature does not exceed 78°C. The test results validate the ability and potential of using vapor-compression refrigeration system in high heat flux CPU cooling.