Calculation of Exergy Loss in Process Industries Using Omega-Enthalpy Diagram

Having calculated the exergy loss for all pieces of process equipment, it is possible to show the thermodynamic irreversibility, which makes certain guidelines for modifying the process industries and improving their performance. In this study the exergy loss is calculated using Omega Composite Curves, which is a novel graphical tool for calculating exergy loss in heat exchanger networks. Unlike other current tools, this graph is linear and calculation of exergy loss using the rectangular shaped area is so easy. The Omega-Enthalpy diagram is used to calculate exergy loss for other unit operations. First, how to achieve this diagram is explained and then the diagrams are used for exergy loss calculation in two case studies. In the first study, each of a PRICO process (LNG production) equipment was investigated especially the multi-stream heat exchanger. The results showed that in the whole process 27.66 MW of exergy is wasted. In the second study, the heat exchanger network of Shazand thermal power plant was investigated and exergy loss of this network was calculated by 8.14 MW.