http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/RSS.ashxDanfoss Silicon Power PagesFri, 20 Feb 2009 13:48:33 +0100http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=1http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=1Danfoss Silicon Power „Shower Power“ New Cooling Concept Outline: • Basic idea • Cost issues • Optimising • Measurements h [W/(m2 K)] 14000 12000 10000 8000 6000 4000 2000 0 0 2 4 6 Flow rate [l/min] 8 10 Pin fin Shower Power • Concepts May 2003 DEDDS Technology "Shower Power" 12009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=2http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=2Danfoss Silicon Power „Shower Power“ New Cooling Concept Today’s Status of the Standard Liquid Cooling Approach: Pin Fin – design for increased turbulence and surface Serial liquid coolant transport between main inlet & outlet • High tooling cost and/or • High manufacturing cost e. g. May 2003 • Temperature gradient • High pressure drop =5x Cost of flat baseplate 2 Cost of pin fin baseplate DEDDS Technology "Shower Power"2009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=3http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=3Danfoss Silicon Power „Shower Power“ New Cooling Concept The Initial New Idea: Parallel Supply of Coolant Out of Many Inlet Nozzles Vs. Serial Use of the Coolant Plus • Many outlet nozzles inject the coolant against the baseplate to avoid temperature gradient • Minimised pressure drop • Inexpensive flat baseplate • Inexpensive plastic parts are capable to guide the liquid (and avoid thermal short circuit) te basepla Minus • Velocity of the liquid decreases quickly between individual inlet & outlet nozzles May 2003 DEDDS Technology "Shower Power" 32009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=4http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=4Danfoss Silicon Power „Shower Power“ New Cooling Concept Advanced New Principle Parallel Liquid Injection + Meandering Channels Power Module with integrated driver board and flat baseplate Plastic „Shower Power” for flow management Liquid outlet Plastic or metal base for liquid inlet and outlet Liquid inlet and distribution to individual cooling cells May 2003 DEDDS Technology "Shower Power" 42009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=5http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=5Danfoss Silicon Power „Shower Power“ New Cooling Concept Automotive Applications: Liquid Cooling for Customised Power Modules Specific advantages: • Flexible and inexpensive cooler design • Dramatic cost savings by using flat baseplates only (esp. for thermal super materials, e.g. AlSiC, CuW, CoMo or Graphite) • Main inlet/outlet base can be integrated into bottom of inverter housing May 2003 DEDDS Technology "Shower Power" 52009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=6http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=6Danfoss Silicon Power „Shower Power“ New Cooling Concept Industrial Applications: Liquid Cooling for Standard Power Modules Specific advantages: • Parallel cooling of separate operating power modules (no Temp.-gradient) • Standard flat baseplate is sufficient • No thermal grease interface May 2003 DEDDS Technology "Shower Power" 62009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=7http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=7Danfoss Silicon Power „Shower Power“ New Cooling Concept Characterisation - CFD Calculations on Nozzles Danfoss bondable frame First simulation (using CFD): Cooling area: 160x70mm2 Nozzles: 112 inlets, 90 outlets, Ø2mm Ethylene-glycol/water 50%/50%, 10l/min Nozzle system Power dissipation: 1000W, uniform flux through Cu only Tin=328K, Tbaseplate=354K ⇒ Rth=26mK/W or Rth x cm2=2.91Kcm2/W ⇒ h ≈ 3400 W/(m2K) ∆Pressure=19mbar Temperature distribution on ½-module Flow velocity distribution on ½-module Problem: Flow velocities get too low when liquid leaves nozzles: Velocities in nozzles 0.5-0.7m/s, drops to 0.1-0.2 m/s giving too low heat transfer coefficients. May 2003 DEDDS Technology "Shower Power" 72009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=8http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=8Danfoss Silicon Power „Shower Power“ New Cooling Concept Optimisation, understanding the system Goal: increase the heat transfer coefficient, h A large number of empirical relationships using dimensionless numbers exist, that describe heat transfer. Example: Nusselt number for forced convection, turbulent flow: applies for 2300 < Re < 106 and 0.6 < Pr < 500 Re Using dimensionless numbers to characterize the system: Reynolds, Prandtl, Nusselt… Reynolds number vs. nozzle diameter and number of nozzles @10l/min Re=2300 marks the limit between laminar and turbulent flow 8000 6000 4000 2000 10 12 24 40 40 90 where: h = individual heat transfer coefficient [W/m2·K] d = characteristic length [m] (e.g. tube diameter) A = cross-sectional area [m2] s = wetted perimeter [m] dh = hydraulic diameter [m] = 4·A/s λ = thermal conductivity [W/m·K] ρ = density [kg/m3] v = velocity [m/s] µb = dynamic bulk viscosity [Pas] µw = dynamic wall viscosity [Pas] L = tube length [m] Re = Reynolds number [ - ] Pr = Prandtl number [ - ] 0 2 2.5 3 3.5 4 Nozzle diameter [mm] 4.5 5 Conclusion: (by inspecting the chart) maximum number of nozzles allowed for Re>2-3000 is 2025 for channel geometries of Ø2-3mm -smaller geometries are not desirable due to the risk of clogging DEDDS Technology "Shower Power" 8 May 20032009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=9http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=9Danfoss Silicon Power „Shower Power“ New Cooling Concept Optimisation, designing the system Problem: Maximum number of nozzles allowed is 20-25 for the Danfoss module and maximum channel diameter is Ø2-3mm. How to connect inlet and outlet nozzles? Same Reynolds numbers Inlets and outlets connected through meandering channels “Tracing” (using CFD) shows that liquid is mixed at every change of direction The shorter the channels, the larger the Nusselt number and thus heat transfer. Therefore, the meandering geometry yields much higher heat transfer than the straight channels Inlets and outlets connected through strait channels le f modu o e t la p base Copper May 2003 DEDDS Technology "Shower Power" 92009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=10http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=10Danfoss Silicon Power „Shower Power“ New Cooling Concept Optimisation - CFD Calculations on Nozzles + Meanderings Examples of Shower Power Labyrinth calculation: Channel cross section: 3mm x 3mm, wall thickness: 1mm. Total power dissipation: 1000W ⇒ 41.7W per cooling cell 10l/min total flow ⇒ 0.47l/min per cooling cell Tin=328K, Tbaseplate=350K ⇒ Rth=22mK/W or Rth x cm2=2.46Kcm2/W ⇒ h ≈ 4000 W/(m2K) Channel cross section: 2.5mm x 2.5mm, wall thickness: 0.7mm, 0.25mm gap between baffle and baseplate Tin=328K, Tbaseplate=338K ⇒ Rth=10mK/W or Rth x cm2=1.12Kcm2/W ⇒ h ≈ 9000 W/(m2K) ∆pressure = 90mbar Temperature distribution across the copper baseplate, variation from 349-350K ∆pressure = 115mbar (270mbar without gap) Temperature distribution across the copper baseplate, variation from 337-339K By reducing channel geometry from 3mm x 3mm to 2.5mm x 2.5mm, flow velocity is increased 50%, and the number of changes of direction is increased from 8 to 11 increasing the mixingeffect. Overall improvement of heat transfer: >200% May 2003 DEDDS Technology "Shower Power" 102009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=11http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=11Danfoss Silicon Power „Shower Power“ New Cooling Concept Investigation on Efficiency: Pin Fin vs. Shower Power 14000 12000 h [W/(m2 K)] Extrapolate to 10l/min: h = 12.500 W/(m2K) 10000 8000 6000 4000 2000 0 0 2 4 6 Flow rate [l/min] 8 10 Pin fin Shower Power Device under test and test bench at University of Applied Science in Kiel. Ethylene-Glycol/Water 50% / 50% May 2003 DEDDS Technology "Shower Power" 112009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=12http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=12Danfoss Silicon Power „Shower Power“ New Cooling Concept Investigation on Homogeneity, ∆T across Baseplate 5 T1 x T2 x 4 3 Shower Power Pin fin Liquid T/K Pin fin T1 x T2 x 2 1 0 0 -1 2 4 6 8 10 Flow rate [l/min] Ethylene-Glycol/Water 50% / 50% Shower Power May 2003 The temperatures on the baseplates were measured using an infrared camera. The temperatures of the liquid were measured using Pt100 sensors in the liquid stream. DEDDS Technology "Shower Power" 122009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=13http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=13Danfoss Silicon Power „Shower Power“ New Cooling Concept Independent test at the Fraunhofer IIS, Erlangen Measurements performed by Herr Ernst Schimanek, Fraunhofer Institut für Integrierte Systeme und Bauelementetechnologie IISB, 2003.03.10. May 2003 DEDDS Technology "Shower Power" 132009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=14http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=14Danfoss Silicon Power „Shower Power“ New Cooling Concept Econo3 module concepts May 2003 DEDDS Technology "Shower Power" 142009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=15http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=15Danfoss Silicon Power „Shower Power“ New Cooling Concept Large module concepts May 2003 DEDDS Technology "Shower Power" 152009-02-20T13:48:33+01:00http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=16http://nozebra.ipapercms.dk/Danfoss/DSP/DSPShowerPowerInfo/?Page=16Danfoss Silicon Power „Shower Power“ New Cooling Concept Odd-shape cooler concept The Shower Power concept is not limited to planar geometries. This example shows a module configuration that could be integrated into a tubular housing. May 2003 DEDDS Technology "Shower Power" 162009-02-20T13:48:33+01:00