In the quest to enhance the efficiency of electric vehicle (EV) air conditioning systems, particularly in frigid climates, a groundbreaking study has emerged that could redefine low-temperature heating strategies. Published in *Zhileng xuebao* (translated as *Journal of Refrigeration*), the research, led by Zhang Tian, explores the potential of the hot-gas bypass cycle to significantly improve heating performance in EVs.
The study addresses a critical challenge faced by EV manufacturers: ensuring rapid and efficient heating of passenger compartments in low-temperature environments. Traditional reverse Carnot heat-pump cycles often fall short in extreme cold, struggling to quickly reach the desired air outlet temperature. This limitation not only affects passenger comfort but also raises concerns about energy efficiency and battery life.
Zhang Tian and his team proposed a novel solution: the hot-gas bypass heat-pump cycle. By bypassing refrigerant from the high-pressure side to the low-pressure side, the system increases the suction pressure of the compressor, ensuring stable operation even in sub-zero temperatures. “This approach not only enhances the heating capacity but also reduces the time required to achieve the target temperature,” Zhang Tian explained.
The researchers developed a staged hot-gas-bypass heat-control strategy, incorporating an additional exhaust throttle valve to expedite the establishment of high pressure. To validate their findings, they built a simulation model using R290 as the refrigerant and constructed a test bench to calibrate the model. The results were impressive: under low-temperature conditions of -25°C and -20°C, the proposed system outperformed the traditional reverse Carnot heat pump cycle. Notably, the optimized control strategy reduced the time to reach the target air outlet temperature by 36% compared to pre-optimization strategies.
The implications of this research are profound for the automotive and energy sectors. As the demand for EVs continues to grow, so does the need for efficient and reliable heating solutions. The hot-gas bypass cycle offers a promising avenue for improving energy efficiency and reducing the environmental impact of EVs. “This technology could be a game-changer for EV manufacturers, providing a competitive edge in the market,” Zhang Tian noted.
The study’s findings, published in *Zhileng xuebao*, highlight the potential for innovation in the field of automotive air conditioning. As the industry continues to evolve, the hot-gas bypass cycle could become a standard feature in EVs, ensuring optimal performance and passenger comfort in even the coldest climates. This research not only advances our understanding of low-temperature heating but also paves the way for future developments in sustainable and efficient transportation.