Industrial compressed air system analysis: Exergy and thermoeconomic analysis

摘要

In manufacturing, compressed air systems generate, store and distribute energy in the form of compressed air for use throughout facilities. However, compressed air is considered as one of the most expensive energy carriers which is accompanied with very high inefficiencies and losses. According to the thermodynamic concept of technical work, the delivered mechanical work to the consumers and pneumatic drives by the compressed air is influenced by the change of the pressure and flow rate of compressed air. Therefore, it is promising to minimize the losses regarding these parameters. It has been argued that exergy concept is more suitable for evaluation of the efficiency of the compressed air system compared to the energy analysis. Exergy analysis can highlight and classify internal (irreversibilities) as well as external (waste heat) losses. In this study, in the context of sustainable manufacturing, compressed air system is evaluated based on energy consumption, exergy efficiency and thermoeconomics. Therefore, exergy weighted sum (EWS) is introduced as an analysis factor which encompasses all the above analysis criteria for the energy efficiency optimization decision support. It is emphasized that EWS can be used for evaluation and comparison of the alternative improvement scenarios or technologies. The results of exergy weighted sum indicate that recovery of the waste heat as well as reduction of air leaks are the best energy efficiency optimization scenarios regarding the power consumption, exergy efficiency and thermoeconomics for the investigated compressed air system.