[Goenitz]

Hi all,

To apply a boundary condition for methane steam reforming the expression is (dT/dy)i=R*delHi/lambda.

T is temperature, y is height, R is reaction rate, delH is enthalpy of formation, and lambda is thermal conductivity. It is a surface reaction.

Because reaction may have many species besides CO and H2 like CO2, H2O etc so dT/dy needed to be calculated for each specie (dT/dy)i. Where 'i' can be CO, H2 etc



my question is how to assign a single wall all these temperature boundary condition for each specie? Even if it is summed and apply as a single quantity 'dT/dy=Sum(R*delHi)/lambda', then how to assign this function to the wall which is parallel to flow (x direction) whereas function is dependent on 'y' coordinate.

P.S i said so because, units are in K/m so we cannot multiply it with length of wall (L) to have units in K.

[Goenitz]

In simple term, if dT/dy =200 K/m on a wall that is parallel to x'axis. (normal boundary condition to wall)

[Gert-Jan]

I really have no idea what you are trying to do.
There is only one temperature. So there is only one dT/dy at the wall. Not 10.

You are looking for R(CO), R(H2O), R(H2) which then have to be something like:

Ri = di/dt = ai*delHi/lambda/(dT/dy).with ai a certain constant of species i.

[Goenitz]

Originally Posted by Gert-Jan

I really have no idea what you are trying to do.
There is only one temperature. So there is only one dT/dy at the wall. Not 10.

You are looking for R(CO), R(H2O), R(H2) which then have to be something like:

Ri = di/dt = ai*delHi/lambda/(dT/dy).with ai a certain constant of species i.

Thank you for your response. See attachment for more clarity. I need T calculation at catalyst site.

Actually, I think dT/dy is temperature gradient between j-1 and j node or like plug flow reactor at entire length of y at each section. But I think is temperature gradient, (between j-1 and j) so I just need to calculate it at that node and multiply it by x (0 to i).
Like single integral, but with x as variable (though it doesn't make any sense)