. Applied thermodynamics for engineers. Fig. 46. Arts. 157, 158, 159, Cycles.* give the areas IT or h. Let us conceiveof a diagram in which only one coor-dinate will at present be named. Thatcoordinate is to be absolute of specifying the other coordi-nate, let it be assumed that subtendedareas on this diagram are to denotequantities of heat absorbed or emitted,just as such areas on the PV diagramrepresent external work done. As anexample of such a diagram, consider Fig. 47. Arts. 158, 16-,, 171. —En- ^ i tropy Diagram. Fig- 47. Let the substance be one * The a
. Applied thermodynamics for engineers. Fig. 46. Arts. 157, 158, 159, Cycles.* give the areas IT or h. Let us conceiveof a diagram in which only one coor-dinate will at present be named. Thatcoordinate is to be absolute of specifying the other coordi-nate, let it be assumed that subtendedareas on this diagram are to denotequantities of heat absorbed or emitted,just as such areas on the PV diagramrepresent external work done. As anexample of such a diagram, consider Fig. 47. Arts. 158, 16-,, 171. —En- ^ i tropy Diagram. Fig- 47. Let the substance be one * The adiabatics are distorted for clearness. In reality they are asymptotic. Manyof the diagrams throughout the book are similarly out of drawing for the samereason. 92. ENTROPY 93 pound of water, initially at a temperature of 32° F., or ° abso-lute, represented by the height ah^ the horizontal location of thestate h being taken at random. Now assume the water to be heatedto 212° F., or ° absolute, the specific heat being taken as con-stant and equal to unity. The heat gained is 180 B. t. u. Thefinal temperature of the water fixes the vertical location of thenew state point c?, the length of the line cd. Its liorizontal lo-cation is fixed by the consideration that the area subtended betweenthe path bd and the axis which we have marked ON shall be180 B. t. u. The horizontal distance ac may be computed from theproperties of the trapezoid abde to be equal to the area abdo dividedhj l{ab + ed)-^2\ or to 180 ^ [( + ) ^ 2] = Thepoint d is thus located (Art. 163). 159. Application to a Carnot Cycle. Ordinates being absolutetemperatures, and areas subtended being quantities of heat absorbedor emitted, we may conclude that an
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