DAVIS, — A PQ PLANE FOR THERMODYNAMIC CYCLIC ANALYSIS. G53 



definite cousumptiou of fuel is determined by the conditions imposed, 

 and should not be exceeded. 



Many other interesting cyclic properties can be studied by means of 

 the P Q plane. As an example, the curves of highest temperature {T,^ 

 have been plotted for types A, B, and C, and are shown in Figures 19, 20, 

 and 21. This quantity T^i is important, not only structurally, but also 

 because the nature of a gas is found to change very materially by reason 



100 



150 



350 



400 



200 250 300 



Figure 19. 

 Ti/pe A. Hif/hest temperature. For adiabatic cycles 



500 

 BTU 



of dissociation when the temperature is raised above a certain limit. On 

 this account it may sometimes be^ necessary to consider, in addition to 

 the two limiting values T^ and V, a third upper limit T,i, which the 

 highest temperature should not exceed, and to rule out a part of the 

 VT^ area on account of the new condition_ 7^^ ^ ^</- In all three cases 

 the part of the area surrounding the V T^ corner would be the first to 

 become unavailable on this account, so that the simple results obtained 

 above would have to be somewhat modified. The graphical methods 

 of this paper would, however, lead directly to the desired results in 



