Calculation of temperature increase in a reacting gas system

[Thiophilus]

How can I calculate the final temperature of a reacting gas-phase
system at an arbitrary temperature? For instance, O2 and H2 in
nitrogen at 120 deg C.

I have looked up enthalpies of formation (at 298K) for all the
starting components and H2O vapor, and can calculate the enthalpies at
the elevated temp, and I think I can calculate the heat of reaction at
120 deg C...

Not sure where I go after that. If I iteratively calculate temps and
product enthalpies to match the heat of reaction (in essence matching
the starting enthalpy), I get calculated temps that are too high.

Th

[Lynn McGuire]

Post by Thiophilus
How can I calculate the final temperature of a reacting gas-phase
system at an arbitrary temperature? For instance, O2 and H2 in
nitrogen at 120 deg C.
I have looked up enthalpies of formation (at 298K) for all the
starting components and H2O vapor, and can calculate the enthalpies at
the elevated temp, and I think I can calculate the heat of reaction at
120 deg C...
Not sure where I go after that. If I iteratively calculate temps and
product enthalpies to match the heat of reaction (in essence matching
the starting enthalpy), I get calculated temps that are too high.
Th

You can always use a process simulator such as DESIGN II
for Windows at www.winsim.com . We give out free two test
drive passwords.

Lynn

[Thiophilus]

Post by Lynn McGuire

Post by Thiophilus
How can I calculate the final temperature of a reacting gas-phase
system at an arbitrary temperature? For instance, O2 and H2 in
nitrogen at 120 deg C.
I have looked up enthalpies of formation (at 298K) for all the
starting components and H2O vapor, and can calculate the enthalpies at
the elevated temp, and I think I can calculate the heat of reaction at
120 deg C...
Not sure where I go after that. If I iteratively calculate temps and
product enthalpies to match the heat of reaction (in essence matching
the starting enthalpy), I get calculated temps that are too high.
Th

You can always use a process simulator such as DESIGN II
for Windows at www.winsim.com . We give out free two test
drive passwords.
Lynn

Thanks, that is a nice offer, but I have a curious mind, and I want to
know how to do it.

Th

[Lynn McGuire]

Post by Thiophilus

Post by Lynn McGuire

Post by Thiophilus
How can I calculate the final temperature of a reacting gas-phase
system at an arbitrary temperature? For instance, O2 and H2 in
nitrogen at 120 deg C.
I have looked up enthalpies of formation (at 298K) for all the
starting components and H2O vapor, and can calculate the enthalpies at
the elevated temp, and I think I can calculate the heat of reaction at
120 deg C...
Not sure where I go after that. If I iteratively calculate temps and
product enthalpies to match the heat of reaction (in essence matching
the starting enthalpy), I get calculated temps that are too high.
Th

You can always use a process simulator such as DESIGN II
for Windows at www.winsim.com . We give out free two test
drive passwords.
Lynn

Thanks, that is a nice offer, but I have a curious mind, and I want to
know how to do it.
Th

See the CEA code at
http://www.grc.nasa.gov/WWW/CEAWeb/ceaRequestForm.htm

CEA is "a program which calculates chemical equilibrium product
concentrations from any set of reactants and determines
thermodynamic and transport properties for the product mixture.
Built-in applications include calculation of theoretical rocket
performance, Chapman-Jouguet detonation parameters, shock tube
parameters, and combustion properties."

Lynn

[Thiophilus]

Post by Lynn McGuire

Post by Thiophilus

Post by Lynn McGuire

Post by Thiophilus
How can I calculate the final temperature of a reacting gas-phase
system at an arbitrary temperature? For instance, O2 and H2 in
nitrogen at 120 deg C.
I have looked up enthalpies of formation (at 298K) for all the
starting components and H2O vapor, and can calculate the enthalpies at
the elevated temp, and I think I can calculate the heat of reaction at
120 deg C...
Not sure where I go after that. If I iteratively calculate temps and
product enthalpies to match the heat of reaction (in essence matching
the starting enthalpy), I get calculated temps that are too high.
Th

You can always use a process simulator such as DESIGN II
for Windows at www.winsim.com . We give out free two test
drive passwords.
Lynn

Thanks, that is a nice offer, but I have a curious mind, and I want to
know how to do it.
Th

See the CEA code at
http://www.grc.nasa.gov/WWW/CEAWeb/ceaRequestForm.htm
CEA is "a program which calculates chemical equilibrium product
concentrations from any set of reactants and determines
thermodynamic and transport properties for the product mixture.
Built-in applications include calculation of theoretical rocket
performance, Chapman-Jouguet detonation parameters, shock tube
parameters, and combustion properties."
Lynn

Thanks, Lynn.

I will have a look at the NASA files.

Th