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Two-Phase Heat Exchanger for Power Electronics Cooling

National Renewable Energy Laboratory

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Technology Marketing Summary

The size, weight, and cost of power electronic components are factors which influence the cost of hybrid and electric vehicles. According to a report from Oak Ridge National Laboratory[1], power electronics can make up 40% of the total traction drive cost in hybrid vehicles. Increasing vehicle electrification, in an effort to reduce the nation's dependence on foreign oil, requires making electric drive vehicles cost competitive with conventional gasoline powered vehicles. A means of reducing the cost of hybrid and electric vehicles is through reducing the cost, weight, and size of automotive power electronics.

Heat dissipation is a limiting factor in reducing the size and cost of the power electronic devices. Current power electronic devices are sized larger to spread heat and thus allow for reliable operation. Significant cost reductions can be achieved by decreasing the size of these silicon-based electronic devices. Increasing the heat dissipation through the use of highly efficient cooling schemes allows for greater power density (heat per volume) which is a means to reduce size, weight, and cost of power electronics. Two-phase cooling offers some of the highest heat transfer rates – higher than those possible with conventional, single-phase liquid cooling systems typical of automotive heat exchangers.

[1] Energy and Environmental Analysis, Inc., 2007, "Technology and Cost of the MY2007 Toyota Camry HEV- Final Report," Technical Report No. ORNL/TM-20071132, Oak Ridge National Laboratory.



Engineers at the National Renewable Energy Laboratory (NREL) have developed a two-phase cooling strategy combined with innovative features (i.e., dual-side cooling, increased heat spreading, and extrudable fabrication design) that has the potential to significantly increase power densities and thus reduce size and cost of power electronics. The passive (i.e., pump-less) nature of the system may also increase overall vehicle efficiency.

It is estimated that almost 6 million hybrid electric vehicles (HEV) have been sold worldwide and their sales are expected to grow in future years. This increasing trend towards vehicle electrification has also increased the demands for plug-in hybrid electric (PHEVs) and electric vehicles (EVs). All electric vehicles (e.g., HEV, PHEV, and EV) require power electronic systems and thus could benefit from the highly efficient cooling technology invented at NREL.

  • Dual-sided cooling of the power modules utilizing an indirect two-phase cooling scheme for increased heat dissipation
  • Increased lateral heat spreading within the evaporation for increased heat transfer
  • Extrudable evaporator design for low-cost manufacturing
  • Limited inclination effects on performance
  • Condenser and evaporator can be one unit or split to allow for flexibility
Applications and Industries
  • Passive cooling
  • Power electronics cooling
  • Two-phase cooling
  • Vehicles
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Application 20160123637
Described herein are passive cooling systems utilizing two-phase heat-transfer fluids for transferring heat from one or more heat sources.
National Renewable Energy Laboratory 10/29/2015
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
NREL ROI 13-36PrototypeAvailable12/11/201512/11/2015

Contact NREL About This Technology

To: Eric Payne<>