U.S. Army Dedicates Research Study to Advancing Cooling Systems for Thermal Management Needs

May 24, 2020 by Rushi Patel

Thermal management of electronics is critical for high-reliability applications and is essential to improve the performance of electrical systems such as those in EVs, smartphones, and laptops.

The U.S. army's command center (known as the C5ISR Center) has recently announced a collaboration with the University of Maryland to enhance the thermal management of electronics by working on advancing their cooling systems


What Is a Thermal Management System?

All electronics require a thermal management system. Its purpose is straightforward: Keep your device temperature below its maximum capacity (and ideally at room/ambient temperature). The performance of electronics degrades as temperature increases from the ambient temperature. The temperature of a device increases when the device is on since no system operates at 100% efficiency.

Output power is not equal to the power fed to the device, and the difference between this is power loss. Power loss appears as thermal energy, which increases the temperature of the device. A large number of research papers target improving the efficiency of electronics in terms of reducing stress on thermal management.

If system efficiency is higher, then the size of the heat sink decreases. This helps to create more compact and powerful devices that are more durable. 


Tackling Thermal Design Issues

The thermal energy due to power loss is removed through conduction (surface), convection (air), or radiation (space) mode of heat transfer. There are numerous methodologies to implement these different modes of heat transfer. The most common technique is a passive heat sink in the form of fins protruding out of metal.

A heat sink, which has high thermal conductivity, increases the area of heat conduction. The result is that heat is rapidly removed from the hot area to the surrounding medium (which is at a lower temperature). 

One of the most common challenges in thermal design is removing heat from hot spots and using the available cooling system effectively. For example, to implement the forced-air cooling placement of a fan has to be done to remove heat from the components which are most likely to get heated and critical for the reliability of the system.

If done incorrectly, it deteriorates the performance and durability of the system. Another standard method for cooling is using liquid coolant. The advantage of using liquid coolant over fans is that they do not consume additional power and compact the system. 


University of Maryland researchers Dr. Raphael Mandel and Harsimran Singh.

University of Maryland research scientist Dr. Raphael Mandel and graduate research assistant Harsimran Singh using a custom-coded model in the Engineering Equation Solver software to perform a simulation of flow distribution. Image credited to the U.S. Army


The Cooling System Collaboration

Researchers from the University of Maryland are working with the US Army to prevent excessive heating produced by military technologies from damaging sensitive electronic components. These efforts will serve the military in the design and development of electronic warfare systems and directed energy applications.

As stated by Dr. Raphael K. Mandel, assistant director of the University of Maryland's Smart and Small Thermal Systems Laboratory, the R&D efforts will be applied to the Army's Future Vertical Lift (FVL) program. They will be used as requirements for electronic warfare and survivability equipment.

The Use of Liquid Coolant in Commercial Applications 

The use of liquid coolants for cooling electronics has made massive progress for the EV industry. In battery chargers, the current rating is limited by the capacity of the material to dissipate heat. As the demand for faster-charging speed in EVs is increasing, engineers have turned towards a liquid cooling system. Tesla has been using liquid coolant for charging connectors and batteries to keep them operating at safe temperatures. This has allowed them to increase their charging rate capacity. 

Recently, researchers from the American Chemical Society have reported using a hydrogel to recover waste heat and reduce the temperature of electronics. To demonstrate this, they attached hydrogel to a cell phone battery during fast discharging. Part of the waste heat was converted into five μW of electricity, and the battery temperature decreased by 68 ºF. Although recovered energy seems small, it can be used for monitoring the battery or control of the cooling system. 

With increasing requirements of features and functionalities expected from modern devices in every industry, power requirements are also becoming stringent. The liquid cooling system is touted to be a next-gen solution for thermal management in electronics.