Simulating free radiation to space

I am trying a thermal simulation for the described problem:

We have a very hot fluid flowing through a pipe. The pipe is wrapped in insulation. The pipe is in Outer Space. 

How can i model a domain that simulates conditions for space? I would like to see how the thermal distribution in the pipe. 

I have tried modelling space as a fluid volume that holds the "void" material properties. However, this is not working for the radiation equation. 

The key goals here are to see the surface temperature on the outer wall of the pipe.