Abstract
Compressed air systems are among the major consumers of electrical energy in industry. As the importance of energy-efficiency grows in general, so does the need for valid and reliable metrics for discussing efficiency. Today, energy flow diagrams are a common tool to illustrate energy efficiency in compressed air systems. They are however subject to various shortcomings which are mainly related to their lack of transparency and reproducibility. Therefore, a novel approach for the assessment of efficiency is presented which is based on the exergy concept. This approach allows for a transparent calculation of flow diagrams for compressed air systems, including the possibility to illustrate the effects of a heat recovery system. The concept is illustrated at the example of an industrial set-up starting at the compressor inlet and ending at the application. The resulting diagram allows a more transparent and objective view on efficiency evaluations and thus contributes to a better understanding of energy-efficiency in compressed air systems and related applications.