ABSTRACT
Capital and operating cost are usually thought of as trade-offs in process optimization. There is wasted capital in transferring the heat in and out, in addition to the capital cost for excess utilities. There are pulse combustion furnaces sold into the home heating market which are advertised as having close to 100% efficiency. Exergy is a quantitative measure of the ability to cause change. By contrast with energy, exergy can be destroyed. This occurs with irreversibilities which increase the entropy of the system. Exergy, rather than entropy, is used in analysis, since entropy gives ambiguous information when there are simultaneous changes in temperature and pressure. A process exergy analysis can be used for identification of the biggest losses in a process, either by section or by pieces of equipment. It also can stimulate creative changes to the process which would enhance the overall process efficiency. Unfortunately, some presentations of exergy analysis suggest excessive complication and difficulty.
