PRINCIPLES OF NAVAL ENGINEERING 



sooo 



7000 

 iOOO 

 5000 

 4000 

 3000 

 2000 

 lOOO 

 



30 35 40 45 



VOLUME (CUBIC FT PER LB) 



147,68 

 Figure 8-15.— Group of isothermal curves on 

 p-v diagram. 



the melting (or freezing) point; the liquid-vapor 

 curve indicates the effects of pressure on the 

 boiling point; and the solid-vapor indicates the 

 effects of pressure on the sublimation point. 



VOLUME 



147.69 

 Figure 8-16.— A p-v diagram for water. 



SOLID.LIQUID 

 CURVE — 



■ CRITICAL POINT 



LIQUID-VAPOR 

 CURVE 



SOLID.VAPOR 

 CURVE 



TEMPERATURE ' 



147.70 



Figure 8-17.— A p-T diagram. 



The intersection of these three equilibrium 

 curves shows the triple point— that is, the single 

 pressure and temperature at which all three 

 phases can coexist. The termination of the liquid- 

 vapor equilibrium curve indicates the critical 

 point— that is, the point at which the liquid and 

 the vapor are no longer distinguishable because 

 their properties are identical. 



Other two-dimensional diagrams that find 

 application in engineering include the tempera- 

 ture-entropy (T-s) diagram; the enthalpy- 

 entropy (h-s) diagram, also called the Mollier 

 diagram; the pressure-enthalpy (p-h) diagram; 

 and the enthalpy-volume (h-v) diagram. Of these, 

 the Mollier diagram is probably of major im- 

 portance in the study of steam engineering. 

 Mollier diagrams are included in many steam 

 tables and are also available in engineering 

 handbooks and some thermodynamics texts. 



ENERGY RELATIONSHIPS EN THE 

 SHIPBOARD PROPULSION CYCLE 



At the beginning of this chapter it was stated 

 that the shipboard engineering plant may be 

 thought of as a series of devices and arrange- 

 ments for the exchange and transformation of 

 energy. Many of these transformations and 

 energy exchanges have been discussed in this 

 chapter, but they have not been taken up in se- 

 quence. Figure 8-18 illustrates the basic 



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