Analysis of R290 Refrigerant and Full Secondary Loop Heat Pump Technology for Ford Electric Vehicles

1.The Dilemma of “Extreme Thermal Challenges” in Electric Vehicle Thermal Management

Driven by the dual-carbon goals and the timetables for banning the sale of fuel-powered vehicles in various countries, the penetration rate of electric vehicles (EVs) is entering a period of explosive growth. However, issues such as drastic range reduction in low temperatures and battery overheating in high temperatures have always been pain points in the industry. Data shows that the range of traditional non-heat pump models may decrease by more than 30% in a -30°C environment. Even with heat pump systems, they still rely on high-voltage heaters for energy supplementation under extreme conditions, and their energy efficiency performance falls short of expectations.

In the 2027-2032 greenhouse gas compliance pathways proposed by the U.S. Environmental Protection Agency (EPA), all scenarios point to a higher penetration rate of EVs, which poses triple challenges to the energy efficiency, adaptability, and environmental friendliness of thermal management systems. In particular, the proposed PFAS ban in the European Union has put the application cycles of traditional fluorinated refrigerants such as R-1234yf and R-134a on the countdown, urgently requiring breakthrough solutions for the industry.

2.Iteration of Thermal Management Architecture: From Direct Confrontation to Systemic Collaboration

The current thermal management of electric vehicles is mainly divided into three architectures:
（1）Direct System (ATA)
In traditional ATA systems, heat exchange is achieved through air-air heat transfer, featuring a simple structure. These systems are matched with high-voltage heaters, resulting in relatively low energy efficiency at low temperatures. Additionally, refrigerant connections require high-torque designs, leading to high platform adaptation costs.

（2）Semi-Secondary Loop (SSL)
SSL introduces water-water heat exchange, simplifying the refrigerant circuit while maintaining moderate control complexity. The evaporator is universal with internal combustion engine (ICE) models, making it suitable for transitional phases.

（3）Full Secondary Loop (FSL)
FSL integrates components such as compressors, heat exchangers, and coolers into modular systems, enabling pre-charging and pre-leak detection. Compared to traditional systems, FSL reduces refrigerant charge by 25% and decreases the number of parts by 30%, achieving a fully modular solution.
Core Breakthrough: The full secondary loop decouples the thermal management system through a “refrigerant-coolant” dual-loop design, upgrading it from a decentralized structure to a highly integrated modular unit. This not only saves assembly space but also reduces heat loss by 20% via compact design—laying the hardware foundation for the application of natural refrigerants.

3.R290 Refrigerant: From Flammability Risk to Performance Dark Horse (with Detailed Advantages)

Among traditional refrigerants approved by SNAP, R-134a, R-1234yf and others are facing bans due to PFAS issues, while R744 (CO₂) is limited by the durability of mechanical compressors. However, R290 (propane) has risen to prominence with its “counterintuitive” performance advantages, and its technical strengths are fully demonstrated under critical operating conditions:

（1）Low-Temperature Heating: Breaking Free from Electrical Heating Dependence
Under typical severe cold conditions of -10°C, traditional R-1234yf semi-secondary loop systems rely on combined operation of heat pumps and high-voltage heaters. At this point, the system’s comprehensive COP (Coefficient of Performance) is only 96, and the additional energy consumption of high-voltage heaters directly reduces driving range. In contrast, the R290 full-secondary loop solution employs vapor injection (VI) technology, enabling the heat pump itself to meet heating demands independently. The COP is significantly elevated to 120 — meaning that for the same heating capacity, the energy consumption of the R290 system is reduced by over 20% compared to traditional solutions, completely eliminating reliance on high-power electric heating elements.

（2）High-Temperature Refrigeration: Dual Improvement in Efficiency and Reliability
Facing extreme high temperatures of 40°C, electric vehicles (EVs) must simultaneously address the dual challenges of cabin cooling and battery heat dissipation. Data shows that in this operating condition, the COP of the R-1234yf semi-secondary loop system is only 79. In contrast, the R290 system leverages higher volumetric efficiency and optimized compressor control strategies, with its COP surging to 148—nearly doubling performance. More critically, its compressor speed is reduced from 11,000 rpm in traditional solutions to 9,000 rpm, which not only reduces mechanical losses by 20% but also significantly improves noise, vibration, and harshness (NVH) performance, creating a more stable operating environment for high-voltage components.

（3）System-Level Optimization: From Charge Volume to Modularization
The natural properties of R290 bring multiple derivative advantages. Its PFAS – free composition directly averts the risk of future EU bans. The 25% reduction in refrigerant charge not only decreases the risk of pipeline leakage but also enables the “pre – charged ex – factory” of the full – secondary loop module. As a result, the final assembly plant does not need additional charging equipment, and the connection process is simplified from a high – torque refrigerant interface to a standardized coolant pipeline. This enhances both production efficiency and the reliability of system sealing.

Core Data Comparison (Source: Ford’s Actual Tests)

Technical Key Points:R290’s critical temperature (96.7°C) and boiling point (-42.2°C) perfectly cover the typical operating temperature range of electric vehicles (-30°C to 50°C). Its high volumetric efficiency allows the compressor to operate at lower speeds with the same displacement, balancing efficiency and reliability. The essence of these advantages stems from R290’s near-ideal thermophysical properties:
The critical temperature (96.7°C) exceeds the peak heat demand during high-temperature operation, ensuring effective heat dissipation under extreme conditions.
The boiling point of -42.2°C guarantees efficient evaporation in low-temperature environments, maintaining heating/cooling performance in cold climates.
Combined with the compact design of the full secondary loop (20% smaller volume than traditional solutions), this achieves a triple breakthrough of “small size, high performance, and low emissions”.

4.On the Eve of Commercialization: Three Core Challenges and Breakthrough Paths

（1）Flammability Safety Design
The A3 flammability classification of R290 (explosive concentration range: 2.1%-9.5%) necessitates systematic protection measures:
The refrigerant circuit is strategically routed to “safety zones” such as the chassis, physically isolated from the passenger compartment.
High-precision leak detection sensors and active concentration control strategies are integrated to establish a three-layer safety barrier: hardware isolation, leakage monitoring, and concentration dilution.

（2）Breakthrough in Material Compatibility
To address R290’s slightly higher operating pressure (approximately 15% higher than R-1234yf), it is necessary to optimize the strength of compressor casings, heat exchanger tubing, and sealing materials. Additionally, specialized synthetic lubricating greases must be developed, with material compatibility verified through thousands of hours of durability testing to ensure reliability throughout the entire lifecycle.

（3）Collaborative Development of Industry Standards
Relying on the SAE CRP collaborative research project, companies such as Ford and Denso are jointly developing special safety specifications for R290, covering details such as charge limits, leak detection thresholds, and maintenance operation procedures, to promote the implementation of global unified technical standards and accelerate supply chain collaboration.

5.The Future is Here: Thermal Management Technology Roadmap

According to Ford’s plan, the R290 full secondary loop solution has entered the bench and vehicle verification stages, with the goal of passing the U.S. SNAP certification and achieving mass production by 2029. Compared with traditional solutions, this technology can help electric vehicles improve their range by more than 15% in -20°C environments, enhance high-temperature fast-charging efficiency by 20%, and meet the EU’s 2030 PFAS ban requirements.

From an industry perspective, this is not just a single refrigerant replacement but a paradigm shift from “component piecing” to “systemic innovation.” The integration of the full secondary loop architecture with natural refrigerants is defining the technical benchmark for the next generation of electric vehicle thermal management — when energy efficiency, safety, and environmental protection are unified, the “all-weather usability” of electric vehicles can truly become a reality.

Conclusion

The competition in electric vehicle thermal management is essentially a dual race between “energy efficiency density” and “environmental friendliness.” The combination of R290 and full secondary loop technology is not only a passive response to regulatory pressures but also an active innovation to break through performance bottlenecks.