Wrong Temperature/Pressure In heat exchanger simulations
 

Hello
I am simulating a Shell and tube heat exchanger. Model info is given below;

Boundary Conditions: velocity inlet and Pressure Outlet
Model: K epsilon realizable with standard wall function.
Mesh Metrics: Skewness max .84, average .23
Mesh type hex with tetra as shown in the attachment below
All of these settings are based on previous research papers that have been identified to be satisfactory.

My Problem Case 1:
I have to validate my results against a previous research(geometry same as that of paper). But my outlet temp is 336 K when it should be 330 K. My pressure results are okay in this case.

My Problem Case 2:
in second case when I do simulations for the same heat exchanger but changing one parameter( baffle cut to 25%), my temp results are reasonably fine. In paper out temp is 336, mine is 338 but pressure results are almost double. Paper gives 9000 pa mine are 18000 pa.

Solutions Tried By me:
1) All tetra mesh gives same results.
2) K epsilon with RNG, Standard Same result.
3) Finer Mesh No improvement.
4) Convergence is fine.

Help would be highly appreciated. Thanks In advance