Temperature is a crucial variable in many industrial and mechanical processes. Diverse applications require integrated thermal management solutions to help remove excess heat. When it comes to product design and engineering, it’s essential to understand some key thermal management concepts and the fundamentals of managing temperature in electronic devices.
What Is Thermal Management?
Thermal management is how engineers and designers can control the temperature of a system with technology. These thermal management technologies are based on heat transfer and thermodynamics.
Engineers can use thermal management to increase or decrease the temperature and change the temperature distribution of a specified system. The thermal management system may cover all possible modes of heat transfer, including conduction, convection and radiation, to move heat from one place to another.
Thermal management is a wide-ranging term involving the creation, movement and removal of heat for various applications in many industries. From buildings to electrical devices to the human body, heat transfer can help regulate temperatures for diverse applications.
Keeping Your Devices Cool
Different devices have varying temperature thresholds they can withstand, so maintaining optimized temperatures for the specified system is crucial. All circuits and devices generate some excess heat during use, and extremely high temperatures can compromise the operation of any electronic.
Most people have experienced the lag that occurs when a computer or smartphone gets too hot. If these problems extend to life-supporting machines, aircraft or electronic components in vehicles or military equipment, the downtime caused by overheating can be dire. To ensure the safety of these circuits and devices, they require thermal management systems. Designers can use different working fluids and heat transfer technology to move heat away from the device in use.
Practical thermal management options for cooling electronic devices include:
- Air cooling: While vapor is a traditional and easy-to-employ form of a working fluid, modern cooling demands often surpass the capability of air cooling systems.
- Liquid cooling: Liquid systems offer sufficient capabilities for many applications. They can be combined with other types of cooling to create a system-level solution.
- Two-phase cooling: These systems use a combination of vapor and liquid fluid types for an innovative cooling solution that can meet strict specifications.
Cooling is just one strategy that engineers can use when creating thermal management solutions for their applications. The system may require several strategies to protect electronics against failure and ensure they meet the ongoing industry demands for faster performance. Keep devices cool with the proper thermal management system to help improve their longevity and reliability.
The Importance of Thermal Management
As products become more electrified, digitally connected, and higher-powered, thermal management becomes even more essential. Thermal management systems aim to close the gap between the system’s specifications and the requirements of its industry. Because the system may be required for devices across varying industries, different strategies are needed to fill the gaps of each one’s unique thermal management needs.
Common strategies for regulating temperature in electronic devices include heating, cooling, heat removal, cycling and temperature homogenization. Engineers can address system temperatures above the ambient temperature with different options for cooling or customized heat transfer technology. Extremely low temperatures can be just as harmful and may require a heating strategy instead. Cycling provides both heating and cooling for the system, with defined temperatures used throughout its run time. Alternatively, the system may need a uniform temperature over a specified length, volume or area. Temperature homogenization strategies help mitigate the risk of unwanted fluctuations.
All devices have a minimum and maximum operating temperature. Outside of these thresholds, their regular operation becomes potentially compromised. Electronics that run closer to their upper limit have a shorter service life before they degrade, making operations unsafe and inefficient. Without proper thermal management, these devices may also become too hot to touch and pose risks for the product’s user experience.
The resulting downtime and potential hazards caused by overheating systems are unacceptable for medical, defense, aerospace and automotive applications. When devices made for other applications feature these same problems, it can harm product sales and company reputations. That’s why many industries have made thermal management a requirement.
How Does Thermal Management Work?
The thermal management system is a specific area of focus or component on the electronic device. Defined borders dictate whether the system can transfer energy, work and mass as expected. Meanwhile, its required specifications describe how effective these transfers are in changing the system’s temperature or temperature distribution. These parameters can either be simplified or made more complex with multiple components, different materials, varying sizes, combining fluid types and stable or transient behaviors.
The particular material used to produce each component is crucial for the thermal management of electronic devices. Because mica has a naturally superior high-temperature resistance and stability, it provides suitable insulation for vital electronic components. In the aerospace and energy industries, thermal management similarly supports reliability. Various forms of working fluids, heat transfer technologies and other system parameters regulate heat differently for diverse applications.
The heat capacity of a system designates the amount of heat needed to raise its energy level. Whether energy is transferred into the system or created by an internal source, the resulting increased energy levels cause the temperature to rise. Thermal management helps control how much heat is stored in the system and when it needs to be discharged. Solutions cover various heat transfer processes, including conduction, convection and radiation, to achieve desirable thermal management results.
Conduction is where heat travels through physical contact between objects. When solid materials touch, the cooler material naturally draws energy away from the warmer device. This heat transfer process can move a large amount of thermal energy and requires the least surface area, making it effective for many applications.
Convection involves the movement of air to redistribute thermal energy. As cooler air passes by the warm device, excess heat is drawn up and away with the air current. This is because the force of attraction leads cooler, denser molecules to sink as less dense molecules rise.
Most thermal management solutions rely heavily on convection to regulate temperature. Passive solutions use only natural air forces like buoyancy. Meanwhile, active thermal management solutions can speed up the air movement with forced convection from a fan, a pump or a blower. Both convection types are effective methods of heat transfer, and active solutions increase the amount of energy that can be transferred.
Radiation is where heat travels away from objects in the form of electrical and magnetic waves. As charged particles interact and move, they generate coupled electric and magnetic fields. This process converts the kinetic energy of heat into electromagnetic energy, which emits from the source and spreads out as it goes. Radiation often propagates through space via visible or non-visible light.
Applications in a vacuum cannot use conduction or convection, making radiation a necessary option for specific industries. Unless the application must rely on radiation, engineers may disregard this mode of heat transfer in their calculation due to its limited effectiveness.
Choosing the Right Thermal Management System
As end-user demands for faster performance and more power-dense products continue to rise, thermal management systems have become necessary to support safety and efficiency in a wide range of industries and applications.
Applications for Advanced Thermal Management
Thermal management helps mitigate excess heat generation, which can cause critical components to overheat and deteriorate. Managing excess waste heat allows for longer life in components and systems. Thermal management can enhance product design and manufacturability with electronics cooling strategies and systems.
1. Industrial Applications
Many industries and markets require thermal management to prevent deteriorated performance of their processes and operations. Engineers can provide solutions for a wide range of industrial applications, including:
- Motor drives
- Calibration furnaces
- Control cabinet cooling of FPGAs, power diodes, thyristors and others electronics
2. Medical Applications
Thermal management solutions can serve many diverse needs in the medical industry. Different cooling strategies can reduce device operating temperatures, resulting in higher efficiency, an increased duty cycle and enhanced safety for patient contacting surfaces. Precision temperature control and faster thermal cycling can be especially crucial for thermal challenges in medical applications such as:
- Test and measurement equipment
- Sample transportation containers
- Diagnostic equipment
- Surgical devices
- Imaging systems
- PCR devices
- Laser diodes
3. Transportation Applications
Active and passive thermal management technologies can be used to meet the increasing demands of various transport industries, including automotive, rail and electric vehicles (EV). Thermal management for transportation applications must include proper insulation for maximized battery life, ventilation and provisions for extreme weather. Heat-dissipating and heat-spreading technologies can help engineers address thermal challenges in areas such as:
- EV charging stations
- Power electronics
- IGBT and MOSFET
- Brake and suspension cooling systems
- Railway signal control
4. Defense, Aviation and Aerospace Applications
The thermal management of electronic systems is a limiting factor for many applications in the military, aviation and aerospace industries. Common thermal solutions may no longer meet their increasingly challenging requirements. Innovative, reliable thermal management solutions are needed to increase component reliability.
Military vehicles, military and commercial aircraft, spacecraft, satellites and other aerospace equipment and vehicles need solutions for thermal challenges such as:
- Vibration, shock and sustained maneuvers
- Battery thermal management
- Large-magnitude acceleration
- Wide temperature ranges
- Altitude and direction changes
In addition to improving system efficiency and reliability, thermal management in space technology has also proven to reduce the weight of spacecraft. Military electronics and aircraft power systems must be designed to withstand extreme operating conditions and environments. That’s why these thermal management systems include highly reliable component and system-level cooling technologies.
Top 3 Thermal Management Challenges
When selecting thermal management solutions for a specified system, a few challenges may come up in addition to the initial temperature concern. As electronic systems become more sophisticated and deliver higher speeds, their rising power requirements also result in potential challenges like heat spreading restrictions, convection limitations and higher ambient temperatures.
1. Heat Spreading
The thermal conductivity (k) of a heat spreading material is directly related to its effectiveness in thermal management. As electronic systems generate higher operating temperatures, materials that were once adequate to conduct heat away from the device may no longer hold up. This is especially true in high-heat flux devices or concentrated arrays of heat sources.
The quickest solution is to select a higher thermal conductivity material. Today’s top heat spreading materials include copper, silver, diamond, graphite, heat pipes and vapor chambers. However, these materials often come with some trades:
Copper has a high thermal conductivity but a weight penalty, which can be undesirable for many applications.
Silver, diamond and pyrolytic graphite have very high thermal conductivities but are too expensive for most commercial products.
Other material options may need an increased thickness or more layers to obtain adequate thermal conductivity.
Passive, two-phase devices like heat pipes and vapor chambers are often looked at to provide enhanced thermal conductivity without significant weight or cost impact.
2. Convection Limitation
Since many thermal management solutions utilize convection to regulate temperature, any challenges from convection limitation can be detrimental. Check if the air-side temperature rise is too large to meet system or component temperature requirements. Then consider the following aspects of the thermal management system:
Increase the physical size of the heat sink or radiator: The larger the size, the lower the delta T you can achieve. However, weight and geometric limitations must also be considered.
Increase the airflow: Higher air velocity generally leads to a lower delta T achieved. Fan reliability and noise should also be considered when evaluating fan selection.
Optimize design elements: Change the design of components such as fin pitch and thickness.
Improve fin efficiency: Create uniform temperature with advanced heat transfer. Consider how different material properties could help improve heat transfer, too.
3. High Ambient Temperatures
The ambient temperature requires sub-ambient cooling. However, high ambient temperatures pose a unique challenge. This concern quickly eliminates all passive or “above ambient” cooling options.
For low power options, Peltier modules or coolers are often considered:
Peltier modules: Peltier devices are semiconductor components. When the cool side of a Peltier module is attached to a warmer device, the device’s excess heat is transferred to the Peltier module’s hot side using the Peltier effect. Thermal management systems typically use Peltier modules to control temperatures with precise regulation. The lack of moving parts means reduced failure rates and minimal noise. Peltier coolers can keep system temperatures below the maximum limit by themselves, more than other cooling products can achieve independently. However, the active movement of energy also uses more power and adds heat to the overall system.
For higher power sub-ambient cooling, vapor compression cooling is often considered.
Vapor compression: Vapor compression cooling uses refrigerant phase change to transfer heat and effectively cool the heat source to a temperature below the surrounding ambient air. The components of a basic vapor-compression cycle refrigeration system are the compressor, condenser, expansion valve and evaporator.
Partner With Advanced Cooling Technologies, Inc.
As a leading manufacturer of advanced thermal management solutions, we understand the specifications for various industries and are committed to helping our customers meet their unique requirements. ACT specializes in custom two-phase heat transfer technology and thermal management products for diverse electronics cooling applications. Trust ACT to be your partner through any stage of the design cycle — from initial concept generation to thermal management system production.
Call us at 717-295-6061, or contact us online for more information about our thermal management solutions and products today.