Size considerations in applications of exergy analysis

Considerations related to size of application of exergy analysis are examined. Six size categories are considered: sub-device, device, simple system, complex system, macro system, and planetary-scale system. The boundaries between categories are not sharp. It is concluded that many systems investigated with exergy analysis exhibit size-related trends regarding how exergy analysis is performed, and a size categorisation can identify how exergy analysis can most appropriately be applied. The results can help guide exergy users to the most suitable manner of application for a given system and are expected to improve the usability of exergy analysis and increase its application.