Monday
Professors Paul Steen & Jeff Varner will come to class to tell you about their
group’s research.
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A
gas stream containing 60 wt % ethane and 40 wt% butane is heated from 150
to 250 K at constant pressure = 5 bar.
Assume this mixture behaves like and
ideal gas.
What is the rate of heat required?
ethane
T = 150 K, P = 5 bar
T = 250 K, P = 5 bar
V
0.00171 m
3
/kg
0.1288 m
3
/kg
H
314.3 kJ/kg
973.3 kJ/kg
butane
T = 150 K, P = 5 bar
T = 250 K, P = 5 bar
V
0.00139 m
3
/kg
0.00160 m
3
/kg
H
H = 30.0 kJ/kg
237.0 kJ/kg
From: Perry’s table 2-255 for ethane
2-240 for butane
For an ideal gas or ideal solutions
∑
=
i
i
mix
H
x
H
ˆ
ˆ
Real gases do not follow this rule
because of differences arising
from enthalpy of mixing or
enthalpy of solution.