Power and Mobility (P&M)

Vaporizable Dielectric Fluid Cooling for Military Ground Vehicle Hybrid Powertrains and Energy Storage

by David L. Saums


Adequate heat dissipation and temperature control for power electronics are critical requirements for vehicle electrification systems, to enable greater power density, reduce size and weight, and improve system performance and reliability. Substantial improvements in heat removal with an advanced thermal management system can impact power semiconductor device operation, module and system power density, and system reliability. This presentation describes development, testing, and implementation of an innovative two-phase, mechanically-pumped fluid cooling system for power electronic systems which uses a common fluid available in military logistics chains. Attributes of this Vaporizable Dielectric Fluid (VDF) cooling system concept are listed, in comparison to traditional air- and water-glycol cooling systems, with major advantages for overall performance improvement of the power electronic systems for hybrid drivetrains. This system concept has been developed and recently commercialized in a variety of critical power electronic systems. Intended to be designed as a system rather than as individual discrete components developed by independent vendors, optimization for specific operational requirements overcomes traditional concerns in two-phase operation for dry-out potential and bubble blockages, with balanced design for multiple heat sources with low thermal stacking, extreme temperature capability, dynamic optimization with changing loads, and other criteria. Power density increases of up to 40% have been demonstrated with this sealed, hermetic cooling system. Advantages for implementation in heavy vehicle power train electrification and for export power and similar electrical systems are explained, with examination of appropriate coolants for military logistics systems in a sealed, pumped system which requires no maintenance.