High power systems of various kinds have become even more widley deployed than in the past. From 15kW IGBT power systems, to 50kW high density power converters, to even higher wattage for computing racks. As the need for applications for systems with this power has grown, so too has the thermal management solutions that allows these systems to operate at their intended performance levels.
This webinar covers the newest strategies and technologies for these very high power applications. In this technology review webinar attendees will learn:
How the integration of the thermal architecture with electronic architecture can can significantly improve the effectiveness of thermal management.
The use of passive two phase thermosyphon loops for cooling data center racks
How to passively cool outdoor 7.2kW power supply electronics enclosures
The application of a closed rack cooling system based on pulsating heat pipes
The development of a loop heat pipe with kW-class heat transport capability
A new class of graphene enhanced heat pipe with heat dissipation characteristics 3.5x higher than copper
Using multi-stage heat pipe loops for cooling high heat density data centers
The application of pin finned cold plates for cooling high power density converters (HPDC)
Many more new and latest developments in thermal management for high power systems and components will be reviewed.
This webinar, presented by thermal management expert Dr. Kaveh Azar, Ph.D., will address all these issues and more. The webinar is one hour in length with time for questions and answers afterwards online and after the webinar concludes.
Many of today’s electronic devices need the performance of liquid cooling to meet the thermal demands of certain hot components. Liquid cold plates are common cooling systems in high power lasers, fuel cells, battery coolers, motor drives, medical equipment, avionics and other high-power, high-heat flux applications.
Figure 1. A Custom liquid cold plate design by D6 Industries. [1]
Cold plates provide localized cooling by transferring heat from a device to a liquid that flows to a remote heat exchanger and dissipates into either the ambient or to another liquid in a secondary cooling system. Component heat flows by conduction through a thermal interface material and the metal plate to the metal tubing. Then it flows by convection from the internal surface of the fluid path material into the flowing coolant.
A cold plate in electronics cooling is
often an aluminum block with an embedded, coolant-filled metal tube. Another
common cold plate type is made with metal shells that are brazed or friction-welded
together and filled with a liquid coolant. On the inside, the metal shells have integral
cooling fins that are submerged in the coolant.
Tubed
Cold Plates
Embedded tube designs are the simplest
version of cold plate cooling devices. They feature a continuous tube set into
grooves in a metal plate, and are often bonded in place with thermal epoxy. The
flowing coolant moves heat from the component away from the cold plate to a
heat exchanger, where it is cooled before being pumped back into the
plate.
A common example of a tubed cold plate
features an aluminum plate with an exposed copper tube. The tubes can be routed
in different pathways to optimize the thermal performance.
The tubing can be continuous or constructed from straight tubes connected by soldered joints, though joints may increase the potential for leakage.
Figure 2. A Tubed cold plate consists of copper or stainless-steel tubing pressed into a metal plate. [2]
This design can provide a
cost-effective thermal solution for component cooling where the heat load is
low-to-moderate. Tubed cold plates
ensure minimum thermal resistance between the power device and the cold plate
by placing the coolant tube in direct contact with the power device’s base.
Direct contact reduces the number of thermal interfaces between device and
fluid, thus increasing performance for the application.
A variant of this design features a thermal epoxy completely applied over the pressed in tubing and flush with the metal plate surface. These are sometimes called buried tube liquid cold plates. This provides a gap-free thermal interface between the tube and the plate. The epoxy layer protects from any leakage from the metal tube. Another key feature is that that fully buried tube is not exposed to the outside environment.
Figure 3. A buried tube cold plate’s metal tube is covered with a conductive epoxy layer. [3]
The choice of liquid coolant affects thermal performance as well. Choosing the right coolant depends to a great extent on the tube material. Copper tubes are compatible with water and most other common coolants, while stainless steel tubes can be used with deionized water or corrosive fluids.
One cold plate OEM offers a proprietary
technology with a tube locking system and pressing techniques that ensure the
tube is flush with the plate surface, providing good thermal contact with the
component being cooled. This manufacturing method eliminates the need for
thermal epoxy between the tube and plate which improves thermal performance. [4]
Submerged
Fin Cold Plates
Another type of cold plate is an all-metal construction with brazed or friction welded internal fin field.
Figure 4. Standard, liquid coolant-containing metal cold plate [5]
The integral, internal fins increase
the surface area that contacts the fluid and enhances heat transfer. Fin shape
and fin density affect the performance of heat exchangers and cold plates. By
their geometry, the fins also create turbulence, which minimizes the fluid
boundary layer and further reduces thermal resistance.
One high-performance version features tightly packed aluminum pin fins that create turbulence with low flow rate values, resulting in high thermal performance with low pressure drop. In this design, the high density of the internal fins increases the heat transfer area without adding bulk to the cold plate assembly. [6]
Figure 5. Close-spaced pin fins with complex geometry create turbulence with low flow rate values inside submerged fin cold plates. [6]
In most high-performance applications, fins are made of copper or aluminum. Aluminum fins are preferred in aircraft electronic liquid cooling applications due to their lighter weight. Copper fins are mostly used in applications where weight is not an important factor, but compatibility with other cooling loop materials is.
For submerged-fin cold plates, many different fin geometries can be tested to find the best improvement in performance. Some of the most commonly used are louvered, lanced offset, straight, and wavy fins.
Figure 6. Fin designs for submerged-fin cold plates. Clockwise from top: louvered, lanced offset, wavy, and straight fins. [7]
With cooling requirements increasing
in many areas of electronics, engineers are turning to liquid cooling to
replace air cooling. Lower cost, safer liquid cooling systems have also spurred
the trend to liquid cooling.
The prime example is the cold plate – relatively simple in design, affordable, available in alternative versions, and extremely customizable. Cold plates should be considered wherever thermal performance above air cooling is needed.
Advanced Thermal Solutions, Inc. (ATS) is hosting a series of monthly, online webinars covering different aspects of the thermal management of electronics. This month’s webinar will be held on Thursday, Sept. 27 from 2-3 p.m. ET and will cover the design and deployment of liquid cold plates in electronics systems. Learn more and register at https://qats.com/Training/Webinars.
ATS cold plates were displayed at the Richardson RFPD booth with Vincotech’s new mid-power VINcoPACK E3, which is a low-profile package for motion control and UPS applications that features a six-pack configuration. (Richardson RFPD)
The showcased solution demonstrated how a high-powered device easily connects with the mounting patterns manufactured on ATS cold plates to meet industry-standard insulated-gate bipolar transistors (IGBT), such as those from Mitsubishi, Vincotech, which was on display at PCIM (pictured above), and other leaders in the power electronics industry.
The flexibility in the ATS design allows for cooling of high-powered devices, such as those made from silicon carbide (SiC) or gallium nitride (GaN), without the need for associated tooling costs, which are commonly found when changing the mounting pattern of liquid cold plates.
The cold plates have an innovative, high aspect ratio fin field that provides 30% better thermal performance than comparable products on the market and are manufactured to be easily customizable for systems with specific thermal or space requirements.
ATS cold plates are the perfect choice for engineers looking for liquid cooling solutions for high-powered systems.
Richardson RFPD has a rich history of providing engineering solutions and distributing components for the global electronics market, with more than 35 locations around the world and specialized knowledge in power electronics. Richardson RFPD is the leader in helping customers design-in the latest products and most innovative technology from the market leaders on its line card.
PCIM Europe 2018, one of the largest power electronics shows on the continent, featured more than 11,000 visitors, more than 500 exhibition, and more than 800 conference attendees. Having ATS cold plates on display, thanks to the relationship with Richardson RFPD, gave ATS a host of potential new customers for its liquid cooling and power electronics cooling solutions.
For more information about Advanced Thermal Solutions, Inc. (ATS) thermal management consulting and design services, visit https://www.qats.com/consulting or contact ATS at 781.769.2800 or ats-hq@qats.com.
ATS released a line of tube-to-fin, liquid-to-air heat exchangers with the industry’s highest density fins to optimize heat transfer. (Advanced Thermal Solutions, Inc.)
ATS heat exchangers are available in seven different sizes and can be ordered with or without fans depending on your specific design requirements. Altogether, ATS offers 49 different heat exchanger options (not including the customized options to meet customer needs).
To make the selection process easier for engineers, ATS has recently unveiled a new Heat Exchanger Selection Tool that will point engineers to the exact option that will meet the inputted criteria.
The tool asks five questions (measurement type in parentheses):
Air temperature from inlet to heat exchanger (Tai°C)
Heat need to be extracted by heat exchanger (QtotalW)
Water exit temperature from heat exchanger (Tfo°C)
Water flow rate (GPM)
Fan voltage (V)
Plug answers in to these questions and hit the “Optimum Heat Exchanger” button to see which of the ATS heat exchangers fits your specific liquid cooling system needs. Once you have the right part number, you can now purchase the right heat exchanger from Digi-Key Electronics.
For more information about Advanced Thermal Solutions, Inc. (ATS) thermal management consulting and design services, visit https://www.qats.com/consulting or contact ATS at 781.769.2800 or ats-hq@qats.com.
