Thermal simulation helps overcome challenge of 14U chassis with 1700 Watts

NASHUA, N.H., 22 Dec. 2007. Amphenol Total Connection Solutions (TCS) in Nashua, N.H., used the Flotherm software from Flomerics Inc. in Marlborough, Mass., to overcome the thermal management challenges of a 14 rack unit (U) chassis dissipating 1700 Watts.

NASHUA, N.H., 22 Dec. 2007. Amphenol Total Connection Solutions (TCS) in Nashua, N.H., used the Flotherm software from Flomerics Inc. in Marlborough, Mass., to overcome the thermal management challenges of a 14U rack unit chassis dissipating 1700 Watts.

Amphenol engineer Chris Heard simulated the product, which includes 14 100-Watt and two 150-Watt printed circuit boards (PCBs). "This project demonstrates how thermal simulation can be used in the early stages of the design process to minimize expensive late-stage changes and reduce time to market," Heard says.

A network equipment supplier asked Amphenol TCS to perform thermal simulation to verify the new chassis concept. Amphenol analyzed the airflow through the chassis with a hydraulic resistance simulation tool called the Chassis Thermal Analyzer. This tool provides fast simulation results because it does not take the detailed geometry of the chassis into account. Heard evaluated a number of different designs and settled on one that seemed to work best.

The hydraulic resistance tool told Heard that it should be possible to push enough air through chassis but did not explain how hot the air would get or if it would flow into the right places. To answer these questions, Heard used Flotherm computational fluid dynamics (CFD) software from Flomerics.

"Flotherm goes one major step further than our internal code by modeling the entire geometry of the chassis," Heard says. "I can specify where the power is dissipated and the simulation tracks the flow of air and transfer of heat throughout the chassis. We have used Flotherm for 16 years and have developed a high degree of confidence in its accuracy. Most of our larger customers also use the software so we can easily exchange models with them."

For more information contact Flomerics online at www.flomerics.com, or Amphenol TCS at www.amphenol-tcs.com.

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