As global environmental regulations become increasingly stringent regarding the GWP of refrigerants, R290 natural refrigerant has emerged as a promising alternative due to its extremely low GWP. However, its flammable and explosive nature poses significant safety challenges, driving continuous innovation within the industry. This article provides an in-depth analysis of the application and key technologies of R290 in the thermal management systems of NEVs.
1. Industrialization Progress of R290 Natural Refrigerant
The development of R290-based thermal management systems for NEVs is advancing steadily, with mass production expected in the first quarter of 2025. These systems adopt a modular secondary loop heat pump design that reduces refrigerant charge, supports heat pump operation at extremely low temperatures (down to -30°C), and incorporates advanced technologies such as hot gas bypass and vapor injection for enhanced heating performance.
Performance tests on test benches demonstrate that at -30°C ambient temperature, the system achieves a heating capacity of approximately 5.1 kW with power consumption of about 2.2 kW, resulting in a COP of around 2.3, indicating excellent low-temperature heating capability. Vehicle-level testing shows a COP of 3.8 with 470W compressor power consumption during cabin cooling at 30°C ambient temperature, and a COP of 3.5 with 570W compressor power during heating at -7°C ambient, demonstrating significant energy savings.
2. Key Technologies of the R290 System
(1) Vapor Injection to Compensate for Heat Exchange Losses
During both heating and cooling operations, vapor injection technology effectively compensates for the heat exchange losses in the secondary loop system. For example, at an ambient temperature of -30°C with evaporation at -40°C and condensation at 55°C, simulation and optimization designs enable the system to achieve a heating capacity of approximately 5.1 kW and power consumption of around 2.2 kW, thereby improving overall system efficiency.
The R290 low-temperature heat pump compressors are built on advanced technology platforms, including 34cc VPI and 45cc VPI models, offering cooling capacities of 11.4 kW and 15 kW, respectively. They operate within a
high-voltage range of 400-900V and a wide operating temperature range of -35°C to 125°C.
The scroll compressor design has been extensively reinforced, featuring optimized scroll profiles, increased scroll thickness, enhanced motor power and torque, and a dual-seal system for both suction and discharge, significantly improving performance and reliability. Comparative tests against
R1234yf compressors have demonstrated the stable cooling capacity and favorable COP performance of R290 compressors under specific operating conditions.
Bench Testing of R290 Modular Low-Temperature Heat Pump
(3) Lubricant Compatibility and Safety Design
For lubrication, PAG-RFL68EP oil has been selected for its compatibility with R290, offering favorable properties such as viscosity, pour point (-48°C), and flash point (240°C). Compatibility tests confirm that current materials are fully compatible with both R290 and the lubricant, ensuring long-term stable system operation.
In terms of safety, R290 gas sensors employing NDIR (Non-Dispersive Infrared) technology are used to monitor gas concentration based on light intensity differences at the inlet and outlet of the sensing chamber. Once a leak is detected, the system shuts down automatically. Meanwhile, ventilation methods, such as forced cooling fan operation, are being continuously optimized to further enhance system safety.
Alternative Automotive Refrigerants for New Energy Vehicles
(4) Electronic Expansion Valve Adaptation
Existing 3-Ton R1234yf electronic expansion valves have shown good compatibility with R290 in terms of flow rate control curves. The superheat control precision is maintained within 1K (0.5K per step for R1234yf and 0.9K per step for R290), meeting the precise control requirements of R290 systems.
The application of R290 natural refrigerant in NEV thermal management represents a significant breakthrough in addressing both environmental regulations and the demand for high-efficiency heating. Through the integration of vapor injection, optimized compressor design, lubricant compatibility, and advanced safety monitoring technologies, the challenges of efficiency and safety in R290 applications are being effectively resolved.
These technological advancements not only drive the continuous upgrade of automotive thermal management systems but also provide solid support for the efficient operation of NEVs under a wide range of environmental conditions. Continued focus on the practical application and optimization of these technologies will further accelerate the development of green and highly efficient thermal management systems in the automotive industry.
