A practical exergy method for system analysis [of steam power plants]

Conventional exergy analysis can only provide information about the potential or possibilities of improving performance of processes, but cannot state whether or not the possible improvement is practicable and economic. In this paper, a new method is proposed based on better understanding of process performance and improvement. This is achieved by dividing exergy losses into avoidable and inevitable exergy losses. The inevitable exergy losses are defined as the minimum exergy losses which can not be avoided for a process to take place in both technical and economic terms. If the inevitable exergy losses can be determined the attention can only be paid to the avoidable exergy losses which can be converted into useful work. According to this improved understanding, a new practical exergy efficiency is defined and a new graphic representation is proposed. An example about a steam power plant is given using the new method which shows the advantages over the conventional method.