For the challenge of driving range degradation of new energy vehicles in winter and policy requirements for applying environmentally friendly refrigerant, CO2 thermal management technology is gradually regarded as one of the effective solutions in the future. Unlike conventional hydrofluorocarbons refrigerant loops, CO2 thermal management technology is based on transcritical cycles, with significant variations in derived technologies, underdeveloped industrial chains, and a notable influence from environmental policies. All of these factors form the limitation of CO2 thermal management technology, so there is an urgent need for more comprehensive and integrated technical research reviews to support its further development. However, existing academic review studies summarize cutting-edge research directions but fail to guide the industry in developing regularly and orderly under policy planning. Patent-based review studies analyze trends in patent application numbers but lack in-depth discussions on specific technical details and do not consider the synergistic roles of policy, industry, and research in the process of promoting the technology. As the automotive thermal management industry grows alongside the rising sales of new energy vehicles, market competition intensifies. Only advanced technologies that meet both policy and production requirements and develop in an orderly manner can secure a larger share of the technical market. In order to address the problem, this paper provides a patent technology review from both macro and micro perspectives. First, based on 2504 relevant patents, this paper summarizes trends in patent numbers, geographical distribution, major research institutions, and patent status, like most patent-based reviews. Simultaneously, focusing on theoretical and engineering technical characteristics, it outlines key technology developments in three major research and design directions: components, systems, and control across several scenarios, including passenger vehicles, commercial vehicles, and so on. It provides a detailed analysis of the technical characteristics and evolution trends in four areas: key components, system architecture, integrated modules, and control algorithms. Finally, this paper explains the synergistic effects of policy planning, technical limitations, and product outcomes on technological development. It analyzes the constraints of these three factors from both temporal and spatial perspectives and summarizes new technical development requirements of high efficiency, low energy consumption, low cost, and low carbon emissions, providing robust support for the stable development of the CO2 thermal management technology industrial chain. This comprehensive review bridges the gap between academic research, patent trends, and industry needs, offering valuable insights for future innovation and commercialization efforts. Ultimately, it aims to guide the orderly and sustainable development of CO2 thermal management technology, ensuring its effective contribution to the advancement of new energy vehicles and the realization of environmental policy goals.
Ren et al. (Thu,) studied this question.