4. Self-powered Active Cooling System for High Performance Processors

Thermal stability in datacenter’s computing units is fundamental to ensure reliability, and durability of the equipment, besides, environmental concern and new regulations require a reduction of the power used. For these reasons, a novel energy neutral hybrid cooling system is proposed. We describe the design, and the prototype’s performance evaluated both in passive and active cooling modes. During normal operating conditions, the thermo-electric energy harvesting system transforms wasted heat into electric energy, and stores it in super-capacitors while the system is providing passive cooling. Active cooling can be activated when a boost in performance requires CPU overclocking, using free energy from the passive step. After the choice of the most suitable harvesting system we designed and tested the prototype on an ARM based CPU, the future core of low-power server architectures. The proposed governor switches to active cooling mode based on customizable thermal management policies. Experimental results demonstrate good passive cooling performance, and several minutes active cooling exploiting the recovered heat.