The use of such diagrams is demonstrated by the followingtwo examples. If the substance is not water vapor, the "state" of the substance is usually obtained through the use of T-s temperature-entropy and h-s enthalpy-entropy diagrams, available in most thermodynamics texts for common substances. Locate point 1 at theintersection of the psia and the F. Superheated steam at psia and F is expanded at constant entropyto psia. These other properties are usually obtained utilizingeither the Mollier diagram if the substance is steam or the saturated and superheated steam tables,as shown in the Figures A-1 and A The following two examples illustrate the useof the Mollier diagram and the steam tables. Usually,two properties for example, v, p, T, h, s of the substance must be known in order to determinethe other needed properties. In order to solve problems in Thermodynamics,information concerning the "state" of the substance studied must be obtained. Some tables use v for n specific volume because there is little possibility of confusing it with velocity. The following notation is used in steam tables. Portions of the tables are shown in Figure A Both sets of tables are tabulations of pressure Ptemperature Tspecific volume nspecific enthalpy hand specific entropy s. Steam tables consist of two sets of tables of the energy transfer properties of water and steam saturated steam tables and superheated steam tables. Thermodynamics Directory Heat Transfer Directory.
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