DA-07-014 Capture Index: An Airflow-Based Rack Cooling Performance Metric PDF

The dimensionless capture index (CI) is proposed as a cooling performance metric based solely on the airflow patterns associated with the supply of cool air to, or the removal of hot air from, a rack. The capture index is typically a rack-by-rack metric and has values between zero and 100%; higher values generally imply good cooling performance and scalability of a cooling architecture. In many applications, the capture index provides additional information relative to rackinlet temperatures and other cooling indices. In some applications, capture index may be computed in lieu of other metrics. Two variants of capture index are defined: one for cold- and another for hot-aisle analyses. A technique for computing CIs numerically, based on tracking airflow with passive concentrations, is provided along with examples based on CFD simulations. A cluster-wide cooling performance metric based on CI, the total escaped power, is also proposed. Finally, an example shows how CI and total escaped power may be used alongside other metrics to determine an optimized physical arrangement of a given inventory of racks and coolers bounding a hot aisle.

Units: I-P