The second law is still rarely used as a design decision tool. However, information obtained from second law analysis is valuable in the design process for thermodynamic systems. This investigation reviews the past development of second law analysis. A clear, operational vocabulary is established. Then two examples of microcomputer-based design procedures are presented. The first is a second law analysis of refrigeration cycles. As a part of this example, the correlation of physical property data by simple methods is demonstrated. The second example is a second law analysis of gas turbine systems. The salient point is that all of this can be done on a microcomputer, and consequently is readily available to any engineer. / M.S.