DENSO presented alongside Ford at the 2024 ATMO MAC Summit, an event dedicated to the use of natural refrigerants in mobile air-conditioning (MAC), with the joint presentation focusing on the use of a propane (R290)-based full secondary loop heat pump for EVs. Almost one year later, the automotive components and technology supplier was exhibiting at IAA Mobility 2025, a tradeshow for automakers and suppliers held in Munich from September 9–14.
It was there that NaturalRefrigerants.com spoke with Dr. Werner Hünemörder, Senior Technical Manager/Product Planning & Advanced Engineering at DENSO, who presented at ATMO MAC in 2024. In addition to an update on the company’s propane MAC tech, Hünemörder also shared insights into the developing market for natural refrigerants in the MAC sector.
This interview has been edited for length and clarity.
Can DENSO provide an update on the propane-based thermal management system it presented at the 2024 ATMO MAC Summit?
Werner Hünemörder: Over the past year, DENSO has continued advancing its R290 thermal management system – not only the heat pump itself but the complete solution. Our priority is to improve system maturity and integrate robust safety features to ensure readiness when our customers choose to move forward with R290.
How does DENSO view the market for natural refrigerant heat pumps developing between CO2 and propane?
WH: DENSO is actively developing systems for both refrigerants. For over 25 years, we have been developing components for R744 – initially only for AC systems. Ten years ago, at the 2015 Frankfurt Motor Show (IAA), we showcased the first compact R290 module, EcoCube, as a feasibility study. R744 is already available on the market, while R290 requires more time due to regulatory and standardization considerations.
Given the current proposed ban timeline for R1234yf, R290 systems could be ready in time for battery electric vehicles. As presented last year at the ATMO MAC Summit in Berlin, customers recognize benefits in full secondary loop R290 systems, which means a compact, fully closed R290 refrigerant unit and a coolant system that distributes heat within the vehicle.
This approach offers simplified systems with reduced development, testing, control complexity, easier logistics and efficient manufacturing through pre-assembled units by suppliers. We see growing interest in this direction.
“Given the current proposed ban timeline for R1234yf, R290 systems could be ready in time for battery electric vehicles.”
Dr. Werner Hünemörder
Senior Technical Manager/Product Planning & Advanced Engineering at DENSO
In addition to components, some automotive suppliers are currently developing thermal management systems using natural refrigerants. Is this something DENSO is considering?
WH: Of course. DENSO can provide a complete thermal management system, specific parts, or individual components based on customers’ needs. DENSO’s philosophy has always been to develop a deep understanding of the full system because that knowledge is essential for engineering efficient and reliable components.
Has DENSO seen demand for natural refrigerants in electric commercial vehicles, such as buses?
WH: Yes, we are seeing increasing interest in natural refrigerants for commercial vehicles in Europe, including buses. While R744 systems have been under investigation for some time, R290 systems are now also being evaluated. Naturally, additional safety requirements mean the decision-making process in this segment takes longer than in passenger vehicles.
