THERMODYNAMIC CONSISTENCY OF DATA-BANKS

Data sets originated from different sources are typically used simultaneously either in data banks or in data bases of flowsheeting programs. If these data sets concern different kinds of data, they ought to be in accordance with the laws of thermodynamics. This is not assured, however, and in many cases it is not even checked. Methods used for data compilation rely on approximate models, which may bias the residuals. Two model-free methods are proposed, where the residuals of the thermodynamic differential equations are investigated. The first method is a chi(2) test based on a quadratic form of the f residuals, involving variances of the elementary measurements, if they are available. The second method is a rather sensitive trend/shift analysis of residuals, which does not require the knowledge of error variances. The examples are the Clausius-Clapeyron equation, a binary vapor-liquid equilibrium data set and a simultaneous treatment of PVT and caloric data.