Issue with flow weighting in temperature simulation in return pipes (direction=-1)?

[solbes]

Hi,

I'm new to thermo-hydraulic simulations, and I'm trying to understand the theory using this cool package. Everything else seems clear to me, but I ran into one thing that I don't understand.

Let us take the "tree-example" as a case. When simulating the return temperatures (after applying the temperature drop at the consumers), I'm guessing the return temperature at the junction (forks-0) should be a flow-weighted average of the return temperatures coming from the 2 consumers:

T_r1 = [ m1*(T_env+exp(-a1/m1)*(T_r2-T_env)) + m2*(Tenv + exp(-a2/m2)*(T_r3-Tenv)) ] / (m1+m2)

where m1 and m2 are the mass flow rates of the corresponding pipes.

In the code, I don't see this flow-weighting of the exponential terms when calculating the least-squares matrix. I only see the normalisation step, which seems to just calculate the non-weighted average of the exponential terms. In the example this works, since the input flow rates of the two consumers are always equal.

Is there an issue or am I just misunderstanding something?