@Mariusz Iwaniuk 

here the file.

I hope that you can help me.

Best House_work.mw
 

@Scot Gould 

I've never used Mathematica...

@Scot Gould 

the problem is correct as described above, then 1.001*P^(1/8.758).

Do you have any idea?
Thanks.

@Mariusz Iwaniuk 

I'm sorry. Here the text.

Thanks.

P := 0.8314e-4*u1(x, t)*298

qeq := 1.001*P^(1/8.758)

pdepe1 := diff(u1(x, t), t)+0.107*(diff(u1(x, t), x))-0.8e-4*(diff(diff(u1(x, t), x), x))+(1-0.4)*1250*(diff(u2(x, t), t))/0.4= 0

pdepe2 := diff(u2(x, t), t)-0.019*(qeq-u2(x, t)) = 0

sys2 := [pdepe1, pdepe2]

ics := u1(x, 0) = 0, u2(x, 0) = 0

bcs := u1(0, t) = 0.16e-1, (D[1](u1))(3.2, t) = 0

sol := pdsolve(sys2, {bcs, ics}, numeric)

sol:-plot3d(u1(x, t), x = 0 .. 3.2, t = 0 .. 1000);

@Scot Gould 

thanks for your replay.

Here part of my code

What is wrong?

Thanks