Keywords: energy utilisation diagram, power availability diagram, exergy analysis, Rankine cycle, exergy loss analysis, graphical exergy distribution
Extension of energy–utilisation diagram to power availability for exergy loss analysis
Energy–Utilisation Diagram (EUD) has been used to identify exergy loss in general process units, whereas Power Availability Diagram (PAD) provides the difference between exergy changes of two pressure exchangers. Two modifications of the original PAD are proposed for better exergy loss visualisation. Firstly, the energy donor curve is shifted to the location of energy acceptor. Secondly, arrows indicating the exergy change direction are inserted in the diagram. This research leads to Modified Power Availability Diagram (MPAD) that can identify the exergy loss. From the applied Rankine cycle, MPAD was changed in two forms as MCPAD (Modified Cycle Power Availability Diagram) and MSPAD (Modified Subsystem Power Availability Diagram). The results showed that MPAD can presents the exergy profile of the working fluid and MSPAD can reduce the complexity of EUD and show the exergy loss of each unit in the cycle. The advantages of MCPAD can present the graphical exergy distribution.