Working out heat transfer flux in a pipe

[sjh94]

1. Question

2. The attempt at a solution

Now I'm not sure where to go next? Do I work out the local heat transfer coefficient at 1.2m or just the heat transfer coefficient? Using
h = Nu × k/x
or
h = Nu × k/d

Thanks, Sam.

 

[Chestermiller]

If you have turbulent flow, is there a significant thermal entrance region, or does the heat transfer coefficient level off over a very short distance into the pipe? Under what circumstances would you use Nu k/x?