TMT: Active Cooling Modules

The primary goal of the Active Cooling Modules (ACM) program is the development and demonstration of ideas based on novel materials and structures that can provide tens of degrees of cooling for 100W devices in cm-scale cooling modules with coefficient of performance (COP) of 2 or better.

In most modern electronics systems (computers, radios, radar modules, etc.) the electronic device is the warmest element in the system, and waste heat is removed by conduction, spreading, and convection to air, with gradual reductions in the temperature as heat travels from the source to the air. If successful, greatly improved thermal management systems will allow operation of higher-density DoD systems with enhanced performance. A high-performance, efficient active cooling component into a system could allow reductions in the operating temperature of the device, perhaps to sub-ambient temperatures. More broadly, the availability of efficient, high-performance coolers would provide additional margin for thermal management system designers.

A major component of the ACM program is focused on thermoelectric modules, which are currently in wide use for many applications including focal plane cooling, thermal cycling, and commercial products such as portable refrigerators. For applications such as microprocessor cooling, there are significant demands on the performance of thermoelectric materials. 

In order to handle high heat flux (approaching 100 W/cm2), the design of thermoelectric coolers with conventional PbTe materials encounters issues with heat dissipation in electrical contacts and other challenges that impact the performance. The COP for cooling modules is defined as the amount of added energy needed to move a unit quantity of electronic device heat. For conventional PbTe materials, it is very challenging to carry high flux through temperature differences of more than a few degrees with COP greater than one. 

As a result, thermoelectric coolers are rarely used for cooling of high-power electronic devices today.

ACM performers are developing thermoelectric coolers based on enhanced materials, unique architectures, and other physical mechanisms for active cooling that utilize input energy to move heat and provide a cooling effect. The structure and metrics of this program are defined to allow any approach that can meet the performance and geometric metrics for consideration.