UTEMPRA - Unitary Thermal Energy Management for Propulsion Range Augmentation

Jason Lustbader, Eugene Titov, Sourav Chowdhury, Lindsey Leitzel, Mark Santacesaria, Mark Zima, Timothy Craig, Paul Droman, Aamir Khawaja, Murali Govindarajalu, John Rugh

Research output: NRELPresentation


Key hurdles to achieving wide consumer acceptance of battery electric vehicles (BEVs) are weather-dependent drive range, higher cost, and limited battery life. These translate into a strong need to reduce a significant energy drain and resulting drive range loss due to auxiliary electrical loads the predominant of which is the cabin thermal management load. Studies have shown that thermal subsystem loads can reduce the drive range by as much as 45% under ambient temperatures below -10 degrees C. Often, cabin heating relies purely on positive temperature coefficient (PTC) resistive heating, contributing to a significant range loss. Reducing this range loss may improve consumer acceptance of BEVs. The authors present a unified thermal management system (UTEMPRA) that satisfies diverse thermal and design needs of the auxiliary loads in BEVs. Demonstrated on a 2015 Fiat 500e BEV, this system integrates a semi-hermetic refrigeration loop with a coolant network and serves three functions: (1) heating and/or cooling vehicle traction components (battery, power electronics, and motor), (2) heating and cooling of the cabin, and (3) waste energy harvesting and re-use. The modes of operation allow a heat pump and air conditioning system to function without reversing the refrigeration cycle to improve thermal efficiency. The refrigeration loop consists of an electric compressor, a thermal expansion valve, a coolant-cooled condenser, and a chiller, the latter two exchanging heat with hot and cold coolant streams that may be directed to various components of the thermal system. The coolant-based heat distribution is adaptable and saves significant amounts of refrigerant per vehicle. Also, a coolant-based system reduces refrigerant emissions by requiring fewer refrigerant pipe joints. The authors present bench-level test data and simulation analysis and describe a preliminary control scheme for this system.
Original languageAmerican English
Number of pages16
StatePublished - 2018

Publication series

NamePresented at the Thermal Management Systems Symposium, 9-11 October 2018, San Diego, California

NREL Publication Number

  • NREL/PR-5400-72680


  • air conditioning
  • battery electric vehicles
  • battery life
  • BEV
  • climate control
  • drive range
  • heating
  • vehicle thermal management


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