Please don't ban me for asking too many questions. Please bear with me because Im so frustrated with it.

My goal is to compare double pipe heat exchanger heat transfer coefficient calculations and the simulation results of the said parameter,

however Im so frustrated because the calculation results and flow simulations results dont match or even come close. I think, my problem is that

what value of heat transfer coefficient from the surface plot I could compare to the calculation results to have at least closer results.

From the surface plot: