SBIR-STTR Award

The trend of replacing mechanical drive systems with power electronics and electrical drives has led to significant increases in the on-board power requirements in military aircraft. Although electrical systems are typically highly efficient, still a significant portion of the electrical energy is eventually converted into heat, thus leading to thermal management challenges. Moreover, the efforts to outfit aircraft with directed energy weapons (DEW) heighten these challenges. Since these weapons are highly inefficient, a considerable portion of the input energy is converted into waste heat, and this heat must be efficiently removed in order to be able to deploy these DEW systems and other electronics on aircraft. We propose innovative two-phase heat sinks and condensers with very low thermal resistance, reduced coolant flow rate, and more uniform cooling over their surfaces. These heat exchangers contain manifolded microstructure surfaces that produce substantially higher heat transfer coefficients at lower pumping power than other geometries. This technology will result in lighter, more compact heat sinks and condensers, as well as reducing the volume and weight of the other components in the thermal management system. Honeywell Aerospace will work with us in developing performance specifications during Phase I and component testing during Phase II.

Benefit:
Many other military systems that utilize power electronics would benefit from being cooled via compact, two-phase cold plates with low thermal resistance. Besides reducing the volume and weight of the overall system, these cold plates will increase the reliability of the power electronic components be reducing the junction temperatures within the dies of the power modules. The major savings will come when the improved cooling facilitates the use of fewer power modules operating at higher currents, which saves significant component costs besides weight and volume. Commercial applications for this cold plate include power electronics for electric vehicles, distributed power systems, renewable energy (wind and solar), and back-up power supplies. Another important application is cooling the CPU and GPU in server farms. These processors are currently cooled by a rather inefficient series of heat transfer steps, several of which involve air-fluid or air-refrigerant heat transfer. Removing the heat directly from these processors via two-phase heat transfer into a refrigerant will save significant energy as well as cooling hardware.

Keywords:
DEW, DEW, heat sink, Avionics, heat transfer, Thermal Management, power electronics, cold plate, Two-Phase

The trend of replacing hydraulic and pneumatic drive systems with power electronics and electrical drives has led to significant increases in the on-board power requirements in military aircraft. Although electrical systems are typically highly efficient, still a significant portion of the electrical energy is eventually converted into heat, thus leading to considerable thermal management challenges. Moreover, the efforts to outfit aircraft with directed energy weapons (DEW) heighten the thermal challenges. Since these weapons are highly inefficient, a considerable portion of the energy required to operate them is converted into waste heat, and this heat must be efficiently transferred to a suitable heat sink in order to be able to deploy these systems and other power electronics on aircraft. We propose using a new heat exchanger configuration that should result in more compact and lighter weight components by generating higher heat transfer coefficients at lower pumping power than other heat exchanger geometries. In Phase I an aircraft condenser based on this technology was estimated to be 69% smaller and 61% lighter than a state-of-the-art conventional condenser, and the PAO-side pressure drop was reduced by 66%. We will be working with Honeywell Aerospace and the University of Maryland during Phase II.

Benefit:
Many other military systems would benefit from lighter and more compact heat exchangers. Besides reducing the volume and weight of the overall system, the heat exchangers, cold plates, and heat sinks based on this technology will increase the reliability of the power electronic components by reducing the junction temperatures within the dies of the power modules. The major savings will come when the improved cooling facilitates the use of fewer power modules operating at higher currents, which saves significant component costs besides weight and volume. Commercial applications for lighter and more compact heat exchangers, cold plates, and heat sinks include power electronics for electric vehicles, distributed power systems, renewable energy (wind and solar), and back-up power supplies. Another important application is cooling the CPU and GPU in server farms. These processors are currently cooled by a rather inefficient series of heat transfer steps, several of which involve air-fluid or air-refrigerant heat transfer. Removing the heat directly from these processors via two-phase heat transfer into a refrigerant will save significant energy as well as cooling hardware. Industrial heat exchangers are another large market for this technology, since the technology will save both materials of construction and allow for more efficient operations.

Keywords:
heat exchanger, power electronics, Avionics , Thermal Management, heat transfer