Tf = dsolve(' m * CP * DTf = w *(h 1+H2 *(2 * Tf+7))'，' Tf(0)=Tin '，' x ')

Results:

Tf =

- 1/2/H2 * h 1-7/2+exp(2 * w * H2/m/CP * x)*(Tin+ 1/2/H2 * h 1+7/2)

Calculating the known conditions before substitution can reduce unnecessary errors.