Diagnosis is the identification of what is wrong with something that is not working properly. The main question that any diagnosis methodology must answer to, when applied to the design or operation of an energy system can be formulated as follows: Where, how and which part of the consumed resources can be saved by keeping the quantity and specifications of the final product constant. Thermoeconomic diagnosis is the only Second Law based technique devoted to operation analysis. The exergy balance of an installation allows us to allocate and calculate irreversibilities in the production process and to identify the equipment which affect overall efficiency and the reasons thereof. This information, although useful, has proved not to be enough. In practice, when attempting to achieve energy savings in an installation, we must consider that not all irreversibility can be avoided. Thus, the technical possibilities for exergy savings are always lower than the theoretical limit of thermodynamic exergy losses. Moreover, the local exergy savings which can be achieved in the different units or processes of an installation are not equivalent. The same decrease in the local irreversibility of two different plant components leads, in general, to different variations of the total plant energy consumption.
展开▼
