Evolution, status, and trends of exergy research: a systematic analysis during 1997-2020

Exergy analysis, as a core evaluation tool to improve energy efficiency and system sustainability, has been applied in various fields over the last decades, leading to a significant increase of exergy-related publications. However, the existing reviews only analyzed part of publications related to a specific topic and lack a systematic analysis. To fill this research gap, a coupled bibliometric analysis and knowledge map method was conducted on 13,941 exergy-related publications during 1997-2020. Results show that publications increased from 54 in 1997 to 1976 in 2020. Journal of Energy is the most productive journals (1543 publications), and Energy & Fuels is the most popular subject category (9204 publications). Three developing countries in Asia (China, Iran, and Turkey) are the most productive, accounting for 45.87%. The main research objects and methods in this field were identified by cluster analysis. Furthermore, timeline analysis and burst detection analysis show that the new research hotspots or research frontiers will focus on organic Rankine cycle, building industry, multi-objective optimization, and sustainable development. This study further pointed out the future direction of the exergy field: in-depth application of the coupled exergy and exergoeconomic analysis; technologies development for efficient utilization of renewable energy, clean energy, and waste heat; enrichment of exergy framework incorporating environmental perspectives and mathematical methods; adaptation of theoretical research; and system optimization to the needs of social development. Through the review of exergy-related publications, results of this study can help to better identify the research hotspots and provide a valuable reference for future research.