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The effective bulk thermal conductivity however, depends on the porosity of the foam RMFs effective bulk conductivity (ke) may be estimated by Equation (1) [2]. 839-862, 2004. The vertical axis is the effective flat plate film coefficient whereas the X and Y axis of the surface plot show the thickness and the density of RMF, respectively. The short answer is that Duocel Foam can be applied to any type of heat exchanger. The surface temperature of the cold plate was estimated by the temperature measurements with thermocouples on the resistor. Burhan Ozmat received his Ph.D. degree from Massachusetts Institute of Technology as a DOE fellow, MSc and BSc One additional factor to enhance heat transfer that is unique to Duocel metal foam is the ability to compress the material by a factor of up to 6x. You can fix this by pressing 'F12' on your keyboard, Selecting 'Document Mode' and choosing 'standards' (or the latest version It scales down the thickness of boundary layers, thereby generating vortexes and, inducing early transition to turbulent flow, and similarly delays or eliminates the transition from nucleate boiling to film boiling. Currently he works at the OZER Advanced Technologies, he established, The foam conductivity has been computed according to a formula wildly adopted in literature. 18 (Tuesday) 9:00 am - 19 (Wednesday) 5:00 pm, About Us | Subscribe | Advertise | Contribute | Contact UsCopyright 2022 Lectrix. T may be calculated by Equation (3) where w=1000 (kg/m3 ), V= 6.3*10-5 m3 /sec (1.0 GPM), CPW=4184 (J/kg-o C), Tin=21o C, and the maximum allowed surface temperature of the cooled electronic device TMax=60o C. Rth and Pressure Drop Measurements and Calculations: Rth was calculated using the above procedure. The cold plate performance requirement for a high-power electronics device is defined by the thermal resistance. The results of such tests agree with the results of the calculations as presented in Figure 3. As advances in epoxy and silicone materials constantly evolve, manufacturers of advanced electronic systems will find that Download Now, 29julAll Day30International Conference on Advanced Vehicle Thermal Management Technologies, International Conference on Advanced Vehicle Thermal Management Technologies aims to bring together leading academic scientists, researchers, and research scholars to exchange and share their experiences and research results on all. Alle Rechte vorbehalten. Focused on Thermal Management, TIMs, Fans, Heat Sinks, CFD Software, LEDs/Lighting, June 14, 2018 Burhan Ozmat Aerospace, Articles, Automotive, Communications, Computer, Consumer, Data Centers, Defense, Electronics Cooling Blog, Featured, Heat Exchanger, Industrial, IT Products, Medical, Power, Research, TECs. Notice that the cross sections of roughly 2 mm long solid ligaments are mostly triangular. Figure 3. The thermal conductivity of 6061 Al and C10100 Cu, most common RMF materials, are about 170 W/m-K and 390 W/m-K, respectively. Metal Foams A Design Guide, Butterworth Heinemann, pp. Your email address will not be published. Method of manufacturing of RMS heat exchangers depends on the material and the design. Al RMF based HXs can be fabricated with vacuum or dip brazing. Heat SinksDuocel heat sinks are often thinner than standard fins, reducing the overall height by 66% of the heat exchanger. The volumetric heat transfer coefficient and Nusselt number were calculated for different velocities. Duocel foam can elevate a heat exchanger design by utilizing the high surface area and high thermal conductivity of the foam structure to enhance the overall heat transfer of a system, all within a compact and lightweight form factor. The mostly triangular cross section and only a couple of millimeter long ligament geometry of RMF offers significant advantages in convective cooling. A Plexiglas housing of the same cavity depth was fabricated out of a 0.635cm (0.250) thick Plexiglass sheet and screwed to the Al and Cu plates with cork gasket. As new products and technologies push the limits of electronics, heat exchangers are required to remove more heat in smaller volumes. listed if standards is not an option). RFMs demonstrate compatibility with a wide range of liquids and gaseous coolants which makes the technology advantageously suitable for a wide range of commercial and military applications. Local Thermal Equilibrium approach has been used. The thermal resistance of the high performance micro channel type Cu cold plates, among others, is about 0.05o C/W under the same conditions. Metal foam can be applied to all types of heat exchangers as an alternative to traditional fins or microchannels. ERG has designed, developed, and delivered over 1000+ liquid heat exchangers, and countless high performance heat sinks for a wide range of industry applications. An RMF may be brazed to low expansion skin layers and function as a constraining doublesided core heat exchanger (HX) for printed wiring boards (PWBs). Fully enclosed HX/cold plate (CP) configurations require vacuum brazing using solid braze preforms. NY, Harris Power R&D center in Albany NY, Texas Instruments Defense Electronics Center Group in Dallas TX, and IBM Drawing of the Cu RMF Cold Plate, Figure 6. (or is it just me), Smithsonian Privacy The thickness of the RMF has a linear relationship with the effective film coefficient at low thickness which asymptotically approaches its saturation value with increased thickness, similar to that of the fin efficiency. The physical dimensions of its structure, as shown below, does not allow boundary layers to grow and introduce enhanced mixing through eddies and turbulence. Duocel foam cores can be machined and brazed into housings, creating an exceptional thermal interface and simplifying the overall system complexity which results in higher quality and more repeatable parts. Heat transfer measurements were performed on a test rig capable of generating hot gas up to 1000C. The estimated local film coefficient of 1 W/cm20C for 63 cm3 /sec (1 GPM) flow rate was used in generating the thermal performance surfaces shown in Figure 3 [2]. Double and single sided see through functional cold plates (left), top view of the single sided test unit (right). Effective h of 40 PPI 6061 Al (top) and Cu (bottom) RMF HXs with DI water at 63.1 cm3 /sec (1 GPM). Metal foams are innovative lightweight materials with unique heat dissipation properties. Figure 8 depicts the results of CFD analyses for a cold plate built with 30 ppi, 30% dense Cu foam. Materials, Compounds, Adhesives, Substrates. The 3D structure of Duocel foam acts as a matrix to enhance the conductivity of the PCM (typically a paraffin wax), resulting in a more complete transfer of heat into the PCM. Agreement NNX16AC86A, Is ADS down? The thickness range for both the Al and Cu foams is 0-38 mm. Thermal LIVE 2022 is a two-day, free online learning and networking event for electronics and mechanical engineers to learn about the latest topics in thermal management. A common example of a typical heat exchanger is the radiator on a car, or the fan-cooled heat sink in a laptop. Integration eliminates the highly resistive thermal interfaces of soft materials such as thermal pads, pastes or thermal epoxies commonly used to couple discrete devices, Hybrid Multi-Chip Modules (HMCM) of photonic and electronic devices to cold plates. Foam based heat exchangers (typically aluminum or copper foams) operate on the same fundamentals as all heat exchangers, but with increased surface area and turbulent flow to maximize heat transfer, resulting in better performance in a smaller package. Figure 1. Thermal conductivity of the base material (Al, Cu, Ag or others). The s of RMF was characterized using experimental measurements, by multipoint Brunauer, Emmett and Teller (BET) method by adsorption of krypton gas at 77.4 K, and the modelling studies by authors. Pore size measured as PPI, the linear density of pores per inch (5-40 ppi). The results of such calculations are shown in Figures 8 for 30 ppi 30% dense RMF Al cold plate and 30 ppi 45% dense RMF foam cold plates. Figure 5. 55 Greg Street, Sparks, NV 89431 | sales@ergaerospace.com | (510) 658-9785, Highly customizable for all modes of heat transfer, Easy to manufacture into conformal shapes, Can be brazed and bonded for excellent thermal interfaces, Maximize Surface Area to Volume Ratio with pore size and compression, Meet mechanical requirements by tuning ligament cross section, Solid ligaments allow brazing and bonding options for exceptional thermal interfaces, Liquid to Air, Liquid to Liquid radiators. A foam based heat exchanger is a compact and highly efficient technology that transfers heat between two or more fluids in order to control the thermal performance of critical components in a system. A high power electric heater was used to produce hot air at 300C that passed over the foam heat exchanger while the cooling air was blown through it. The ranges of effective heat transfer coefficient for the Al and Cu foams are 0 to 7.5 (W/cm2 o C) and 0 to 15 (W/cm2 o C), respectively. Essentially all of the liquid single- and two-phase heat exchangers that ERG designs take advantage of compressed Duocel foam in order to maximize performance in a small volume. Your internet explorer is in compatibility mode and may not be displaying the website correctly. 40 pores per inch (PPI) 6101 Al based metal foam consisting of nodes and ligaments forming a space filling network of dodecahedrons with 12 pentagon shaped facets. The effective thermal conductivity of 6061 Al based foams biaxially increases to ~ 30 W/m-K when unidirectionally compressed in X direction to 50% relative density in the (YZ) plane where ligaments are aligned in Y and Z directions. 6-20, 2000. One of the most important features of the RMFs is their extremely high and scalable surface area density (s ) compare to those of brazed or extruded fins and fin pins. Duocel metal foams have a high thermal conductivity, high surface area, and high structural integrity that can be integrated into and optimized for all types of heat exchangers. There are quite a few ways to fabricate RMF [1], however the investment casting method of manufacturing produces the most desirable material properties. The effective film coefficient is proportional to the density. [2] B. Ozmat et al., Thermal Applications of Open Cell Metal Foams Materials and Manufacturing Processes, Special Edition, Vol.19, No. To optimize the Duocel structure, ERG customizes the base material (primarily high conductivity metals like aluminum and copper), the pore size (smaller pores like a 40 PPI foam equates to higher surface area to volume ratio), and the ligament size (~8% relative density provides a good conduction path for the heat into the cooling fluid).. The temperature rise of the air, the surface temperature of the heat exchangers and the air temperature inside the heat exchanger were measured. The model was generated taking advantage of Brinkman Equations interface for porous media. HXs with exposed RMF can be fabricated by either dip brazing or vacuum brazing. Produced by Electronic Cooling, it showcases the newest techniques and products in the industry. [3] Brunauer, Emmet, Teller, Journal of the American Chemical Society, Volume 60, 1938, p 309.