Class 29
Monday, November 1st
Enthalpy Tables
Acetone is partially condensed out of a gas stream
containing 66.9 mole % acetone vapor and the balance
nitrogen. 100 moles/s are fed to the condenser at 1
atm and 65o C and the vapor and liquid streams exit at
5 atm and 35oC.
Reference: Ac(l) at 35oC, 5 atm ; N2 at 25oC, 1 atm
Substance
nin
Ac (v)
66.9
Ac (l)
----
N2
33.1
Hin
nout
Hout
3.35
----
63.55
33.1
----
`
Reference: Ac(v) at 35oC, 5 atm ; N2 at 25oC, 1 atm
Substance
nin
Hin (kJ/mol)
nout
Hout (kJ/mol)
Ac (v)
66.9
------
3.35
2.451
Ac (l)
----
----
63.55 -28.22
N2
33.1
.292
33.1
1.168
Q = (2.451*3.35+63.55*-28.22+33.1*1.168)-(33.1*.292)
= -1763 kJ
Saturated steam at 300o C is used to heat a
countercurrently flowing stream of methanol vapor
from 65o C to 260o C in an adiabatic heat
exchanger. The flow rate of the methanol is 5500
standard liters per minute, and the steam
condenses and leaves the heat exchanger as
liquid water at 90o C. Find the flow rate of
entering steam in m3 /min and the rate of heat
transfer from the water to the methanol in kW.
Saturated steam at 300o C is used to heat a
countercurrently flowing stream of methanol vapor
from 65o C to 260o C in an adiabatic heat
exchanger. The flow rate of the methanol is 5500
standard liters per minute, and the steam
condenses and leaves the heat exchanger as
liquid water at 90o C. If the system is the heat
exchanger, what is the energy balance?
a) 0 = ΔH
b) 0 = ΔU
c) Q = ΔH
d) Q = ΔU
Saturated steam at 300o C is used to heat a
countercurrently flowing stream of methanol vapor
from 65o C to 260o C in an adiabatic heat
exchanger. The flow rate of the methanol is 5500
standard liters per minute, and the steam
condenses and leaves the heat exchanger as
liquid water at 90o C. If the system is the
methanol, what is the energy balance?
a) 0 = ΔH
b) 0 = ΔU
c) Q = ΔH
d) Q = ΔU
Saturated steam at 300o C is used to heat a
countercurrently flowing stream of methanol vapor
from 65o C to 260o C in an adiabatic heat
exchanger. The flow rate of the methanol is 5500
standard liters per minute, and the steam
condenses and leaves the heat exchanger as
liquid water at 90o C. What should we use as the
reference state for the steam/water?
a) 
b) 
c) 
d) 
Steam at 300oC
Water at 0oC
Water at 90oC
Water at the triple point
Reference: CH3OH (v) at 65oC; Water (l) at triple pt
Substance
nin
Hin
nout
CH3OH
Water
min
mout
Hout
Reference: CH3OH (v) at 65oC; Water (l) at triple pt
Substance
nin
Hin
nout
Hout
CH3OH
Water
min
mout
What is nin for CH3OH (in mol/min)? The flow rate of
the methanol is 5500 standard liters per minute.
Reference: CH3OH (v) at 65oC; Water (l) at triple pt
Substance
nin
Hin
nout
Hout
CH3OH
245.5
245.5
Water
min
mout
What is Hin for methanol (in kJ/mol)? – vapor at 65oC
Reference: CH3OH (v) at 65oC; Water (l) at triple pt
Substance
nin
Hin
nout
Hout
CH3OH
245.5 0
245.5
Water
min
mout
What is Hout for methanol (in kJ/mol) vapor at 260o C?
Reference: CH3OH (v) at 65oC; Water (l) at triple pt
Substance
nin
Hin
nout
Hout
CH3OH
245.5 0
245.5 10.885
Water
min
mout
What is Hin for water in kJ/kg (saturated steam at 300o
C?
Reference: CH3OH (v) at 65oC; Water (l) at triple pt
Substance
nin
Hin
nout
Hout
CH3OH
245.5 0
245.5 8.37
Water
min
2750.9
mout
What is Hout for water in kJ/kg? (liquid water at 90oC.)
Reference: CH3OH (v) at 65oC; Water (l) at triple pt
Substance
nin
Hin
nout
Hout
CH3OH
245.5 0
245.5 8.37
Water
min
2750.9
What is Q for methanol in kW?
mout
377
Reference: CH3OH (v) at 65oC; Water (l) at triple pt
Substance
nin
Hin
nout
Hout
CH3OH
245.5 0
245.5 8.37
Water
min
2750.9
mout
What is mass of steam required in kg/s?
377
Reference: CH3OH (v) at 65oC; Water (l) at triple pt
Substance
nin
Hin
nout
Hout
CH3OH
245.5 0
245.5 8.37
Water
min
2750.9
mout
377
What is the volumetric flow rate of steam entering the
system in m3/s?