Thermal management architectures for rack based electronics systems

摘要

Cooling architecture options are studied for rack based electronics such as computer servers or router line cards. For the purposes of this investigation, individual servers or line cards are assumed to be of the horizontal pizza box style with a few high power modules such as CPU's or high power ASICS and a number of other lower power packages, memory, I/O chips etc. A number of system architectures for cooling the high power modules are considered and the corresponding performance levels that can be achieved are evaluated. In the first, fairly conventional cooling architecture, a "keep in volume" is allocated around each high power module for local air cooled heat sinks. In the second option, volume for air cooled fin surfaces is provided above the card footprint within the server volume but remote from the high power modules such that a single or two-phase heat transport means is required to transport heat from the modules to the fins in the remote location. In a third option, the heat transport loop at the card level transfers heat from the high power modules to a rack level liquid cooling system that dissipates heat to air flowing through the rack. In a fourth architecture, the heat transport loop at the card level connects to a rack level liquid cooling system that exchanges heat with circulating liquid supplied by a cooling system external to the rack. These options are selected to provide a broad look at cooling design possibilities and tradeoffs. Cooling architecture choices are more limited within racks that contain a variety of servers made by different vendors. The more powerful architectures are feasible within racks where a single vendor owns all the functions and has complete flexibility to consider rack level design tradeoffs.