11.19    The p–y–T relation for chlorofluorinated hydrocarbons can be described by the Carnahan–Starling–DeSantis equation of state

11.27   A gas enters a compressor operating at steady state and is compressed isentropically. Does the specific enthalpy increase or decrease as the gas passes from the inlet to the exit?

11.28   Show that T, p, h, c, and g can each be determined from a fundamental thermodynamic function of the form u 5 u(s, y).

 

 

Â	a0 3 1023	a1 3 103	a2 3 106	b0	b1 3 104	b2 3 108
R-12	3.52412	22.77230	20.67318	0.15376	21.84195	25.03644
R-13	2.29813	23.41828	21.52430	0.12814	21.84474	210.7951         TableP11.19

 

 

11.29   Evaluate p, s, u, h, cy, and cp for a substance for which the Helmholtz function has the form

11.40 Over a certain temperature interval, the saturation pressure–temperature curve of a substance is represented by an equation of the form ln psat  5 A 2 B/T, where A and B

 

y

c 5 2RT ln

y¿

T

2 cT ¿ c 1 2 T ¿

T

1       ln

T ¿

T

T ¿ d

are empirically determined constants.

(a)   Obtain expressions for hg 2 hf and sg 2 sf in terms of

 

where  y9  and  T9  denote  specific  volume  and temperature,

respectively, at a reference state, and c is a constant.

11.30   The Mollier diagram provides a graphical representation of the fundamental thermodynamic function h 5 h(s, p). Show that at any state fixed by s and p the properties T, y, u, c, and g can be evaluated using data obtained from the diagram.

11.31   Derive the relation cp  5 2T102gy0T 22p.

Evaluating Ds, Du, and Dh