transient heat transfer & simulation software help

cobra007

hi everyone;

I've been looking for an easy simulation program to use , for simulating flow and heat transfer through pipes or a piping system.
actually right now i just need to solve this problem but i'll be using it for more complicated things later on (i think):



now here would it be correct if i calculated the outer surface temp. of the pipe normally, then i start using the trasient eq { T-T_infinity/T_i-T_infinity = e^-bt} or it must be solved as transient from the beginning(and this is where i get stuck)

thanks in advance

PS: my friend how did this got the diameters on the drawing mixed up and it could be assumed as lumped system