I am having problems in modeling air fin cooler outlet header, and any help will be appreciated.

The problem is that there is a gap of +/- 9000mm between existing (3) and additional new (2) bundles. It is a two phase flow and equal distribution is crucial. This is a revamp project and there is no space to achieve flexibility of the piping.
So I tought that a simple solution would be to make piping very rigid and strong so that the outlet manifold (14")acts as a trust block between new and old set, and moves bundles easily (7500N per nozzle to overcome the friction force).
Trust blocks do exist between 3 bundles of the existing set as well as between 2 bundles of the new set.

The assumption was made that all bundles are loose except the first one on the right of the existing set and all of them are fixed in front where inlet and outlet header box is.
I model the system as follows:

1. restricted the first right bundle of the existing set in X direction and input other calculated X displacements due to thermal expansion at the other five of the existing nozzles
2. left pipes free at the new nozzles in X direction and input friction force Fx = -7500N
4. run and checked X displacement at the first left nozzle of the new bundles
5. went back to input this X displacement, remove the force from all and input other nozzles displacements due to thermal expansion of bundles,
but the restrain forces (Fx) in the output file (outlet manifold) are exceeding 7500.

How to interpret this? That displacements in input file are wrong because manifold is expanding at 68 degC and bundles at 232 degC?
Allowable loads on air fin cooler nozzles are per API 661. Is my approach making sense at all?