A look at thermal management in electric vehicles

Aug. 1, 2022
R-1234yf—the same refrigerant quickly overtaking automotive manufacturing and aftermarket as the refrigerant of choice for air conditioning systems in other types of vehicles—is dominating the EV space as the preferred refrigerant for heat pumps.

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What you will learn:

There are differences between the HVAC systems on EVs when compared to vehicle with ICEVs

•EV's thermal management systems must support lo carbon-emissions

•Heat Pumps transfer heat energy from the ambient air to the cabin

When shops consider how best to prepare for electric vehicle service, thermal management should be integral to the conversation. And, like many EV topics, servicing these vehicles presents several critical differences from the HVAC systems found in internal combustion engine vehicles (ICEVs).

Unlike traditional ICEVs, thermal management in EVs takes a much more holistic approach to heating and cooling the vehicle. This is because the lack of combustion removes a substantial source of high-quality heat. Moreover, there are several factors driven by EV technology that the thermal management system must consider.

One example is “range anxiety,” which is a driver’s need to be confident they will be able to travel the desired distance on a charge. Energy used for heating, cooling or other functions represents energy no longer available to propel the vehicle. Another differentiator with EVs is their overarching mission to create a healthier, more sustainable planet with low carbon-emissions. An EV’s thermal management must contribute to this mission, especially since OEMs and suppliers are publicly stating sustainability goals.

These and other considerations have led to what, currently, are two main thermal management approaches in EV engineering. The first is the use of a positive temperature coefficient (PTC) heating element. This device draws voltage from the battery for cabin heating—which in turn lowers the vehicle range. This side effect is a key reason we’re seeing fewer new EVs with electric heating coils and more with heat pump systems. Rather than generating heat, heat pumps move heat from one place to another—either absorbing heat from ambient air and transferring it into the cabin for warmth or removing heat from the cabin to cool it. Heat pumps are highly attractive for EVs because, in essence, they utilize an endless reserve of “free” source energy from outside air and transport up to three times its required operating energy load.

A heat pump’s effectiveness relies heavily on its refrigerant. So, it may come as no surprise that R-1234yf—the same refrigerant quickly overtaking automotive manufacturing and the aftermarket as the refrigerant of choice for air conditioning systems in other types of vehicles—is dominating the EV space as the preferred refrigerant for heat pumps. This is due to its low boiling point. In addition to its heat pump benefits, R-1234yf offers similar cooling capacities and vapor densities as legacy refrigerants, delivering superior A/C performance.

Lastly, in terms of the EV mission and helping shops remain compliant with environmental regulations, R-1234yf delivers with:

  • Zero ozone depletion potential (ODP)
  • Low (< 1) global warming potential (GWP)
  • Support of overall greater system efficiency

Shops have an advantage in that they will be seeing more and more vehicles of all types, from ICEVs to EVs and hybrids, coming in for service of R-1234yf-charged systems. Now is the time to prepare by becoming familiar with this refrigerant’s requirements for use and safety protocols, investing in the necessary equipment—such as an R/R/R machine for shops doing a larger volume of R-1234yf maintenance service—and ensuring they have adequate supply on hand to meet the increasing demand from their customers.

About the Author

Adam Kimmel | Senior Principal Consultant—Technical Service

Adam Kimmel has spent nearly 20 years as a practicing R&D engineer and technical consultant for thermal management in the areas of automotive/EV, mobile HVAC, fuel cell systems, and data centers. He has degrees in chemical and mechanical engineering and is currently a senior principal consultant at The Chemours Company, a world leader in titanium technology, thermal and specialized solutions, advanced performance materials, and chemical solutions.

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