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Parallel Integrated Thermal Management

National Renewable Energy Laboratory

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Technology Marketing Summary

Many current cooling systems for hybrid electric vehicles (HEVs) with a high power electric drive system utilize a low temperature liquid cooling loop for cooling the power electronics system and electric machines associated with the electric drive system.  These vehicles may contain additional cooling or thermal management systems for other vehicle components, such as an internal combustion engine, batteries, or the vehicle passenger cabin.  The cost of the separate low temperature cooling loop utilized only for cooling of the electric drive system often adds substantial cost to the overall cost of the electric drive system.  It is therefore desirable to remove the dedicated cooling loop for the power electronics and electric machines to reduce cost and potentially increase cooling system and vehicle efficiency.  In addition, the transition to more efficient electrically dominant vehicle propulsion reduces the available waste heat, bringing challenges related to the vehicle passenger cabin heating or other conventional uses for waste heat.



The present invention provides a solution to managing the combined heat load of two or more vehicle subsystems through a single combined coolant loop having parallel branches for each subsystem.  With proper control, this parallel integrated cooling system can provide effective cooling to the parallel system branches by matching the level of cooling to the heat load, such as to turn off cooling to a subsystem when not needed (increasing overall thermal management efficiency).  The invention also enables the transfer of waste heat from one subsystem to another that requires heat, either through direct heat transfer or through integration with a heat pump.  The parallel integrated thermal management system combines the function of separate vehicle cooling loops to produce a less expensive and more efficient combined cooling system.  The invention also supports the use of waste heat and the integration of heat pumps in electrified vehicles.

Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Patent 8,806,882
Parallel integrated thermal management
Embodiments discussed herein are directed to managing the heat content of two vehicle subsystems through a single coolant loop having parallel branches for each subsystem.
National Renewable Energy Laboratory 08/19/2014
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
NREL ROI 11-04DevelopmentAvailable05/02/201105/02/2011

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To: Eric Payne<>