Modern Engineering Thermodynamics

98 CHAPTER 3: Thermodynamic Properties
70. In 1905, Knoblauch, Linde, and Klebe proposed the
following equation for the specific volume of superheated
steam:
v = 0:5962T/p − ð1 + 0:0014pÞð150,300,000/T 3 − 0:0833Þ
where p is in psia, T is in R, and v is in ft 3 /lbm. Develop a
computer program that returns v when p and T are input.
Allow the use of either SI or Engineering English units.
Compare your results with steam table values at 0.10, 0.50,
1.00, 1.50, 2.00, 2.50, and 3.00 MPa along the 200.°C
isotherm. Plot these results as a percent error in v vs. p for
T =200.°C.
71. Develop a computer program that calculates the pressure of
superheated ammonia vapor from the Beattie-Bridgeman
equation of state when the specific volume and temperature
are input from the keyboard. Allow the use of either SI or
Engineering English units. Using the superheated ammonia
tables (Table C.6), determine the percent error between your
calculated values of pressure and the correct values along the
100.°F isotherm. Plot this percent error vs. p utilizing actual
pressure data of 10.0, 30.0, 50.0, 70.0, 90.0, 140., and
180. psia.
72. The pressure-temperature relation for saturated ammonia can be
written as
logp sat = C 1 − C 2 /T sat − C 3 logðT sat Þ − C 4 T sat + C 5 T 2 sat
where
C 1 = 25:5743247
C 2 = 3295:1254
C 3 = 6:4012471
C 4 = 4:148279 × 10 –4
C 5 = 1:4759945 × 10 –6
In this equation p sat is in psia and T sat is in R. Develop a computer
program that calculates in either SI or Engineering English units
(your choice) p sat in either psia or ΚPa when T sat is entered in either
°For°C. Make sure the screen clearly indicates the proper units on
the input information and all output values. Compare the resulting
output values with a series of corresponding saturation values given
in Table C.5 of Thermodynamic Tables to accompany Modern
Engineering Thermodynamics.
73. The p-v-T relation for superheated mercury vapor is
pv = RT − ðT/vÞexpð10:3338 − 312:095/T − 2:07951 ln TÞ
where p is in N/m 2 , v is in m 3 /kg, T is in K, and R = 41.45 J/kg · K.
Develop a computer program that outputs p, v, and T with their
appropriate units when either (a) p and T are input or (b) v and
T are input. Allow the user to work in either the SI or Engineering
English units and to choose which type of input he or she wishes
to use. For extra credit, create an isometric three-dimensional plot
of a p-v-T surface using this equation of state.