damerell wrote: ↑
Tue Sep 03, 2019 11:06 pm
kitters wrote: ↑
Sun Sep 01, 2019 11:16 am
Glowing heat pipes make me feeling smth wrong and willing to fix pipes wasting energy for glowing.
Very much this. The way steam pipes don't lose any energy in spite of being apparently just lumps of iron already picks at my suspension of disbelief, but heat pipes that glow orange is pretty absurd. A little window in an otherwise insulated pipe would make more sense (although it's not clear _why_ the pipe would have a window...)
Hmm, I tried to find some information comparing copper thermal conductivity to its radiated power, but came up with naught.
So I guess that I'll have to do it myself :
Blackbody radiated power is P = A.σ.T^4, with σ = 5.7x10^-8 W.m^-2.K^-4 (and A = surface area)
So, for 1300 K (=1000 °C), that should be 0.16 MW/m². (Meanwhile, a 300K blackbody environment emits around 460 W/m², so, negligible...)
Note that it's going to be less for (oxidized) copper
Also note, that it would probably be pretty hard to insulate a pipe like that for long before the insulator itself started to glow !
have to read up on those molten metal Russian nuclear subs !
Copper has a thermal conductivity of around 340 W/m/K near 1000 °C
So assuming a 1m long pipe of copper, one end of which is at 1000°C, and the other at 500°C, the energy flux would be :
340×(1000-500)/1 = 0.17 MW/m²
Note that the two /m² are quite different : in the first case, it's the pipe surface area A ; in the second case, it's its cross-section S !
(For a cylindrical pipe, they would be related by S=(τ/2)×R² ; A=1m×τ×R ; S/A=R/2 ;
for R=1m, S/A=1/2)
Wow, I wouldn't have expected these two to be of the same order of magnitude, but the radiative one to be much smaller !
On the surface, it feels to me that Factorio uses a simulation that ends up with much higher effective thermal conductivities ?
P.S.: That's not even considering thermal conductivities of the ground & air around the pipes, and the convection of air...