提高流速对下一代液冷系统的影响.pdf

1、Bill Flaherty,Ph.D.-Alloy EnterprisesWill Martin-nVentImplications of Increased Flow Rates on Next-Generation Liquid Cooling SystemsImplications of Increased Flow Rates on Next-Generation Liquid Cooling Systems Bill Flaherty,Ph.D.-Alloy Enterprises Will Martin-nVentCOOLING ENVIRONMENTS&LIQUID COOLIN

2、GTDP is Only Part of the StoryNew architectures are required in and outof the blade to address these issuesNext-gen3,600 WOn the market1,200 WIn design2,400 WIndustry standards will push flow rateshigher as TDP rises leading to problems:Increased pressure drop Increase pumping power Increased veloci

3、tyDarcy-Weisbach equation defines that pressure drop is proportional to the square of flow rateP Q2Pumping power is proportional to the pressure drop times the flow rate(i.e.the cube of flow rate)Power Q x P Q3Flow Rate and Pressure DropA 4 increase in flow rate can drive a 16 rise in pressure dropp

4、otentially increasing pump power demand by up to 64xIncreasing rack density breaks the LPM/kW industry standardPeripherals plumbed in series add hundreds of watts of effective load Increasing number of GPUs/CPUs per blade increases blade flow rates by up to 8xIncreasing Rack DensityVelocity is propo

5、rtional to flow rateIndustry standard is 10 fps 3 m/s max velocity to minimize erosion1Simplified limit to avoid erosion corrosionStandard under discussion and may changeExcessive velocity can cause:Material degradationIncreased corrosion riskEnd result:leaks that put expensive racks at riskFlow Rat

6、e,Velocity,and Erosion1 ASHRAE Handbook Fundamentals Chapter 33System Level Implications(Model)A FNM simulation of a generic TCS loop was run in MacroFlow to assess potential impact of flow increase for a fixed infrastructureModel Attributes:Fed by In-Row CDU3 Header Manifolds1.5 Rack DropsQty 6 125